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Philosophy of Mind

The mind–body problem: What is the relationship between the mental and the physical?

Dualism

Dualists believe that there are material substances (bodies) and mental substances (minds) that are ontologically distinct from each other.

Plato and Aristotle were Dualists.

In the Phaedo Plato gave two arguments for thinking that souls are not dependent on bodies and can exist separately:

All unseen things are unchanging and ‘simple’ (not divided into parts).Things that don’t have parts can’t be ‘broken up’ or destroyed.The soul is unchanging and simple, so it can’t be destroyed.

Everything comes about from its oppositeWhen you change something, you change it from what it is, to what it (currently) is notLife is changed into death which is separation of soul and bodySo the joining of the soul and a body must cause life For this to happen, the soul must be pre-existent

Plato used the term nous to describe the part of the individual that survives the death of the body

In both arguments, Plato presupposes that the soul exists.

Descartes

In The Meditations Descartes says that that the question “what am I?” can be answered by considering what it is that is essential for him to have to exist.

He says that he can doubt whether he has a body because his perceptual experiences could be mistaken or he could be being deceived into believing he had a body by an ‘evil demon’.

However, he cannot doubt that he is thinking. Because he is thinking he must exist (Cogito ergo sum)

He concluded that he exists as a being “the essence of which is to think”.

The Conceivability Argument and the Omnipotence of God

Once Descartes had established both that he exists and that God exists (the Trademark Argument), he thought it was reasonable to accept that we do have bodies.

It is important for Descartes’ argument that our ‘clear and distinct’ ideas of mind and body are complete and exclusive. The mind is nothing but thought; the body is nothing but extension (a substance that occupies space).

In Meditation VI he presents the following argument for substance dualism:

1. I have a clear and distinct idea of myself as something that thinks and isn’t extended2. I have a clear and distinct idea of body as something that is extended and does not think.

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3. If I have a clear and distinct thought of something, God has the power to create it ‘precisely as I conceive it’

4. Therefore, God has the power to make my mind exist separately from my body

We can understand (1) and (2) to entail the claim that it is conceivable that mind can exist without body. Nothing in our concepts rules this out. Assuming that God is omnipotent, the only reason for thinking that God cannot make something is that the concept of it is contradictory. The concepts of mind and body aren’t self-contradictory. So, God can create the mind and the body just as Descartes conceives of them.

God is included in the argument to bridge the gap from conceivability to possibility: it might be conceivable that I could exist without a body, but that does not show that it is possible.However, God’s omnipotence guarantees that the mind is in principle separable from the body.

We can summarise the argument in terms that don’t refer to God:

I can conceive that the mind can exist without the body.

Therefore, it is logically possible for the mind to exist without the body.

Therefore, mind and body are distinct substances.

Criticisms

Mind without body is not conceivable

Logical behaviourism argues that mental states and events (beliefs, thoughts, desires, choices etc.) manifest themselves through behaviour. Without a body, something can’t exhibit behaviour; and without behaviour, there is no effect of mind. Once we’ve understood this we will realise that mind without body is inconceivable.

What is conceivable may not be possible

Even if Descartes can conceive of his mind existing without his body, this doesn’t mean that it is possible, especially in the absence of an omnipotent God.

In his criticism of the Ontological argument, Guanilo points out that we can conceive of all sorts of non-existent and contradictory things.

If the mind is not ontologically independent, it is impossible for it to exist separately from the body and Descartes conception is wrong.

We need an independent reason to think that the mind is distinct from the body.

The ‘masked man fallacy’

Descartes infers possibility from conceivability – because it is conceivable that mind can exist without body, it is possible that mind can exist without body.

The ‘masked man fallacy’ has been used to show that this inference from what is conceivable or inconceivable to what is the case is illicit. (see Glossary).

The name of the fallacy comes from the example:

Premise 1: I know who Joe is. (I know who x is)

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Premise 2: I do not know who the masked man is. (I do not know who y is)

Conclusion: Therefore, Joe is not the masked man. (Therefore, x is not y)

Descartes version:

I know I am thinking (I have a mind)

I can conceive that I do not have a body

Therefore my mind and my body are not the same thing

The fallacy lies in the jump from conceiving that ‘two’ people or things are distinct, to inferring that it is possible that they are distinct (or impossible that they are not).

Descartes accepts that we cannot generally infer what is possible from what we can conceive, but in the case of clear and distinct ideas, the inference is justified. If we can clearly and distinctly think of some object, x, having a certain property, then not only is it possible that x has that property, it is true. (It is impossible for a triangle to have internal angles that don’t add up to 180 degrees just because it is inconceivable that they should.)

In the Masked Man example my conceptions of Joe and the Masked Man are not clear and distinct. It is only while I do not know who I am thinking of, that the masked man could be anyone.

There are two ways to object to this: either we cannot clearly and distinctly conceive of the mind as separate from the body, as logical behaviourism claims.

OR we can challenge whether ‘clear and distinct ideas’ guarantee truth. Perhaps we can make mistakes concerning even what we conceive clearly and distinctly.

Descartes did not rely heavily on the conceivability argument and he admits the possibility ‘that things ..unknown to me,[the body] are not in truth different from myself whom I know. This is a point I cannot determine.’

What is logically possible tells us nothing about reality

Even if it is logically possible that the mind can exist as a distinct substance, it does not mean that it does.

If we conceive of mind as something that thinks and of body as something that is extended, it does not follow that in certain circumstances, the mind is not extended or that the body does not think.

We can conceive of mind and body as distinct substances, or we can think of thought and extension as properties of the same substance.

The Indivisibility argument

Descartes argues that bodies are extended in space and divisible into spatial parts, but minds have no parts. Therefore, the mind is a distinct substance from the body.

The indivisibility argument depends on the conceivability argument to establish that the mind is a substance. If we know that the mind is a substance, we can say that the mind has properties which the body does not (or vice versa); we can then conclude that the mind is not the same as the body:

The body is divisible into parts

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The mind is not divisible into partsTherefore, the mind and the body are different substances.

Leibniz’s law of indiscernibility later stated that if two things have different properties, they are not identical.

Modern Dualist E.J. Lowe supports Descartes view that as the ‘self’ ‘soul’ or ‘mind’ cannot be divided into parts it cannot be identical to any extended physical object. Similarly, mental states cannot be reduced to physical states of the brain.

Criticisms:

The mental is divisible

The idea that we think and imagine with the whole of our minds is challenged in cases of mental illness, e.g. multiple personality syndrome, in which some ‘parts’ of a person’s mind are unable to communicate with other ‘parts’. Psychologically people may believe or desire one thing ‘consciously’ and the opposite thing ‘unconsciously’.

The way in which the mind is ‘divisible’ is entirely different from the way in which the body is. Bodies are spatially divisible, while minds are only functionally divisible. The different ‘parts’ do different things, but they aren’t in different spatial locations.

The argument assumes that minds exist as substances. If minds do not exist as substances, then we cannot talk about ‘their’ properties. A materialist will claim that there are no ‘minds’, only mental properties – thoughts, desires, pains, etc. which are properties of brains (physical objects). This provides a different explanation of why ‘minds’ are not divisible. Minds are not ‘things’ at all.

Only physical properties are spatially divisible. Most properties (like being a member of a particular species) aren’t the kind of things that ‘take up space’.

Not everything thought of as physical is divisible

Descartes argues that extension is the essential property of physical objects.

He then claims that what is extended is divisible.

It was a matter of some debate in the seventeenth and eighteenth centuries whether physical objects are infinitely divisible. This was not a practical question but a theoretical one.It was also questioned whether there were physical things that cannot be divided even in principle.

It may not be an essential or defining property of every physical substance that it is divisible.

In that case, the fact that the mind is not divisible does not entail that it is not physical.

Do thoughts need a thinker?

In an appendix to the Meditations called ‘Objections and Replies’, Descartes claims that thoughts logically require a thinker.

Substances possess properties. e.g. a chair (substance) is solid (property). Properties can’t exist without substances. Similarly, thoughts can’t exist without a thinker. However, substances can persist through changes in properties e.g. a thinker can have a series of thoughts.

The traditional metaphysical view of substances and properties was challenged by Hume.

Descartes implies that he is the same ‘thinking thing’ that persists from one thought to another.However he may just be a succession of thoughts.

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Even if we agree that there can’t be a thought unless something thinks it, that doesn’t entail that it’s the same subject. Each thinker might exist for just one thought.

Descartes admitted that: ‘I exist – that is certain. But for how long? For as long as I am thinking. But perhaps no longer than that; for it might be that if I stopped thinking I would stop existing’

If Descartes wished to establish that he is the same person from one day to the next, he would need to show that mind is a substance that persists even when there is no conscious thought e.g. in dreamless sleep (Elizabeth challenged this).

Descartes could have replied that he remembers things and that many of his mental states (beliefs, hopes, plans) were the same, so he must be the same substance before and after cessations in conscious thought.

If we accept that thoughts require a persistent thinker, this does not imply that the mind is a mental substance. We could be a physical substance with thoughts.

Substance Dualism and Causal Interactionism

In the Sixth Meditation Descartes endorses dualistic interactionism:

1. Dualism: Mind and body are fundamentally distinct kinds of things (they have different primary attributes).

2. Interactionism. Mind and body directly causally interact with each other.

Descartes maintains that minds and bodies are ontologically distinct and independent.

The mind (or soul) is a non-material ‘thinking substance’ and

the body has material properties (e.g. it is extended in space) and works like a machine.

However, we experience ourselves as embodied minds.

This idea of union is a third ‘basic notion’ alongside our concepts of mind and body.

“Nature also teaches that I am present to my body not merely in the way a sailor is present in a ship, but that I am most tightly joined and, so to speak, commingled with it, so much so that I and the body constitute one single thing”

The idea of mind is known by the intellect, the idea of body is known by the intellect aided by the imagination, but the union of mind and body is known most clearly through the senses.

The mind controls the body, but that the body can also influence the otherwise rational mind, as when people act out of passion.

Most of the previous accounts of the relationship between mind and body had been uni-directional.

Descartes argued that the mind interacts with the body at the pineal gland which is "the seat of the soul" He believed this because the soul is unitary, and unlike other areas of the brain, the pineal gland appeared to be unitary.

Descartes speculated about the nature of the ‘commingling’ of the mind and body:

“my mind is not immediately affected by all the parts of the body, but only by the brain, or perhaps even by just one small part of the brain”

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Certain brain events cause “confused sensations” which enable the mind to detect the needs of the body. Sensations such as colour, sound, smell etc. lead his mind to understand that:

“various other bodies exist around my body, some of which are to be pursued, while others are to be avoided”.

He also thinks that his mind is capable of causing events to occur in his body:

“experiencing pain as if it is occurring in the foot … provokes the mind to do its utmost to move away from the cause of the pain”

But even if the connection between the mind and body is very close this doesn’t mean that they are one and the same thing. We can still conceive of ourselves existing without those ways of thinking that are informed by the body.

It is not clear whether Descartes thought that with the union of mind and body a third type of substance was created.

The Causal Interaction problem

Interactionist dualism faces the conceptual problem of explaining how the mind can cause physical events because:

the mind is not in space and exerts no physical force causes need to be in the same place as their effects mental substance is not subject to the causal laws that govern the physical world, because it

is not part of the physical world

The issue was raised by Princess Elizabeth of Bohemia in letters to Descartes written in 1643

She asks how something that doesn't have any physical properties (i.e. doesn't exist in space, has no extension and no mass) interacts causally with something that is physically extended and has mass or how something happening to the body (e.g. stimulation of our perceptual organs) brings about perceptual experiences and thoughts (e.g., "I see a red chair")

It would seem that for anything to causally affect a physical body it too must be physical or at least have some minimal physical properties.

We can represent this challenge as an argument:

A body can only be directly caused to move by physical contact with another bodybut a non-extended thing can’t make physical contact with anything. So unless X is extended, it can’t directly cause a body to move. (1) If X directly causes a body to move, then X is extended.(2) If X is a thinking substance, it is not extended.(3) So, if X is a thinking substance, X cannot directly cause a body to move.

Descartes endorses premise (2). Elisabeth offers considerations in favour of (1).

This line of thinking is intuitive and is in line with Descartes’s mechanistic physics.

Descartes first responds by saying that we cannot understand or explain mind-body causation by thinking about body-body causation. The two kinds of causation are fundamentally distinct.

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Descartes used the example of ‘weight’. Weight doesn’t ‘push’ an object, it is the result of the force of gravity on the mass of an object, and gravity can operate without contact between physical objects.

In her response, Elisabeth says that she accepts, from her own experience, that the mind does cause the body to move. The problem is that experience gives us no indication of how this happens:

‘This leads me to think that the soul has properties that we don’t know – which might overturn your doctrine … that the soul is not extended.… Although extension is not necessary to thought, it isn’t inconsistent with it either’.

She continues:

I admit it would be easier for me to concede matter and extension to the soul, than the capacity of moving a body and of being moved, to an immaterial being.

Descartes replies that if it is easier for her "to attribute matter and extension to the soul” she should do so. By doing this she will be able to conceive of the union of soul and body, but at the same time come to realise that they are two distinct things! Here Descartes is appealing to the ‘basic notion’ of the union between mind and body.

Descartes himself found it difficult to understand how it is that the mind and body are distinct substances, yet form a ‘unit’. In a letter to Princess Elisabeth in 1643 he wrote:

..it seems to me that the human mind can’t conceive the soul’s distinctness from the body and its union with the body, conceiving them very clearly and both at the same time. That is because this requires one to conceive them as one single thing and at the same time as two things, which is contradictory.

He went on to say that it is the ordinary experience of life that gives us an understanding of this union, rather than philosophical reflection.

Elizabeth finds this unsatisfactory because (a) if the soul is not extended, conceiving it as such will not explain away the interaction problem.

(b) if we are to conceive of the union of body and soul, this would involve conceiving of some sort of causal connection, which is what she is unable to do!

Although Elisabeth was primarily focused on how the immaterial mind could causally influence the actions of the material body, she also asks for clarification on the other side of the interaction problem: how the "passions" (i.e., bodily feelings like hunger or physical pleasure) interact with the non-material mind.

Descartes claimed that the pineal gland is the principal seat of the soul which contained 'animal spirits' which transfer the energy of the mind out into the rest of the brain.

Mind-body interaction is not explained by saying where it happens (especially as this has been shown to be false.)

Some philosophers and neuroscientists have suggested that the immaterial mind might be able to control brain processes by exerting ‘influence’ over the behaviour of neurones within the cerebral cortex; because of the structure of the ‘neural network’.

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Empirical challenges

Substance dualism conflicts with some of the presuppositions of empirical science. The law of the conservation of energy states that in any closed system, the total amount of energy in that system remains unchanged. The energy can only change forms; e.g. movement can produce heat. The universe is usually understood as a closed system in which the total amount of energy can’t change. If the universe is causally closed every physical event has a sufficient physical cause.

1. If the mind, as a non-physical substance, could move the body, the total amount of energy in the universe would increase.

2. Therefore, if the mind could move the body, the law of the conservation of energy would not apply to the universe, and the universe is not a closed system.

While physics can’t tell us everything about what exists, interactionist dualism implies that physics isn’t correct in thinking that physical movement can only be caused by a physical force.

Current science indicates that movements of the body are caused by physical events in the brain. If the mind moves the body, it does so by changing what happens in the brain. If interactionist dualism is true, some events in the brain have no physical cause, because they are caused by the mind. We currently have no evidence for or against the mind changing what happens in the brain.However, neuroscience may discover a totally physical explanation which will make talk of the mind or soul redundant.

The problem of other minds and the threat of solipsism

Substance dualism faces a further challenge of showing that we can know other minds exist. If mental states are reducible to physical states of the brain, then this problem doesn’t arise, since the existence of a correctly functioning brain is sufficient for the existence of a mind associated with it. If minds are independent of bodies, people’s bodily behaviour does not prove that they have a mind.

For interactionist property dualists, the problem is similar; we cannot experience other people’s mental states directly through introspection, all we have to go on is their behavior, expressed through their bodies. It is at least possible that I am the only person who has a mind and that everyone else is an automaton without conscious mental states whose actions are programmed by the brain.

If there are no other minds, then my mind is the only one that exists. This is solipsism.

The argument from analogy

The argument from analogy claims that we can use the behaviour of other people to infer that they have minds too. It was first presented by John Stuart Mill in An Examination of Sir William Hamilton's Philosophy and a more recent version was formulated by A.J.Ayer.

1. I have a mind.2. I know from experience that my mental states cause my behaviour.3. Other people have bodies similar to mine and behave similarly to me in similar situations.4. Therefore, by analogy, their behaviour has the same type of cause as my behaviour, namely

mental states.5. Therefore, other people have minds.

The argument is a ‘common-sense’ view but we can object to its use of induction.

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The conclusion that other people have minds is based on a single case. You can’t generalise from one case, because it could be a special case. Perhaps I am the only person to have a mind.

However, instead of talking about the causal relation in the single case of my behaviour and my mind, we can say that we have experience of many instances of this ‘type’ of behavior:

1. This behaviour has a mental cause.2. That behaviour has a mental cause etc.5. Therefore, many behaviours have a mental cause (I know this from my own experience).6. Other people exhibit the same types of behaviour.7. Therefore, those behaviours also have mental causes.8. Therefore, other people have minds.

The argument still relies on the claim that like effects (behaviour) have like causes (mental states). Even if my behaviour is caused by (my) mental states, that doesn’t mean that the behaviour of other people could not be caused by something different.

Hume challenges ‘cause and effect’ by saying that what we observe in causation is nothing more than a 'constant conjunction’ or regular connection between events

However in this form the argument is not from analogy at all, it is a causal inference intended to make belief in other minds justified. We can think of it as an inference to the best explanation: that other people have conscious experience, and are motivated by beliefs and desires, in roughly the same way we are, this enables us to explain and predict their behaviour.

The private language argument

Ludwig Wittgenstein is often interpreted as using the private language argument to show that doubt about the existence of other minds (or at least, other language users) is self-refuting. The fact that I am using a language meaningfully is enough to show me that I am part of a community of language-users, and so there must be other minds, and solipsism must be false.

Descartes assumes that we can ascribe mental states to ourselves, to say for example that ‘I am angry’. For Wittgenstein, this ability is learned alongside the ability to ascribe mental states to other people. To learn the meaning of ‘anger’ is to learn its application to ourselves and others, to be able to say ‘he is angry’. So even in my own case, mental states are ascribed at least partly on the basis of behaviour rather than introspection. There must be criteria which are shared within a community since otherwise we would be unable to learn the ‘language’ of mental states. A meaningful language must be one with recognized rules, not just a ‘private’ language in which the words get their meaning from our own sensations. This isn’t really a language at all, just a sequence of meaningless noises. If our language only referred to private mental states, we could never be sure that they are being correctly applied to others

The beetle in the box analogy

Wittgenstein claims that language use is causally connected to thought processes. If this was not the case, no one else could understand what I mean by any term since it refers to a wholly private object and I would find it impossible to form a coherent concept of someone else’s experiences on the basis of my own.

Dualists are in a situation in which each person has his or her own box into which only he or she can look. I can see directly what I have, but no one else can; they have to rely on my report about what I have. Each of us calls what we have in our box a ‘beetle’; and while we may suppose that

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everyone’s beetle is the same, it is possible that we all have something different in our boxes. Because we can never compare what is in our boxes, we can never be sure. It is even possible that some people have nothing in their box at all!

. This view has a number of important implications.

If there can be no knowledge of oneself as a mind without presupposing that there are other minds, the problem of other minds does not arise.

Our knowledge of other minds is not inferred from knowledge of our own behaviour and its causes. We don’t have one without the other.

This raises a challenge to substance dualism (mind without body is not conceivable). Mental and physical properties have to be attributed to the same thing for us to attribute mental characteristics to anything.

We don’t know what a mind is unless we already know what a person is - an ‘embodied mind’. The concept of the ‘union’ of mind and body is a more basic concept than the concept of mind.

Eliminative materialists claim that the real explanation of action is to do with the neurological structure of the brain - if the behaviour of others can be explained in principle solely by events within their brain, we do not need to treat them as having minds as well.

Consciousness and Qualia

Descartes pointed to our ability to use language and to reason, especially about mathematics, as beyond the capacity of any physical system. Leibniz argued that we could know everything that there was to know about how a physical mechanism thinks, senses and perceives, and yet this knowledge would not provide us with an explanation of these conscious states. Arguments for the need to locate consciousness in a non-physical mind have also been put forward by contemporary philosophers, notably Thomas Nagel and David Chalmers in ‘Consciousness and its place in nature’.

Chalmers’ view of ‘consciousness’ is similar to Leibniz; it involves ‘perceptual experience, bodily sensation, mental imagery, emotional experience and more.’ Chalmers emphasises the ‘phenomenal character’ or what it is like to be in such a state or how it is experienced in my mind.

Philosophers use the term qualia (singular quale) to refer to the phenomenal character that experiences have. They are what we are immediately conscious of when we experience sensations. Qualia are accessible introspectively, they are ‘subjective’ intrinsic qualities.

Some philosophers (for example Daniel Dennett) deny that qualia exist, most accept that at least some mental states (for example hearing music, being tired, bored, or in pain) have qualia. Strawson proposed the view that ‘every mental state has qualia, since every genuinely mental state is experiential’.

The ‘explanatory gap’ and the ‘hard problem of consciousness’

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The phrase ‘the explanatory gap’ was coined by Joseph Levine to talk about the way in which a materialist or neuro-scientific account of the mind would fail to be 'fully explanatory, with nothing crucial left out'.

Chalmers says that "consciousness" is an ambiguous term, referring to many different phenomena, some of which are easier to explain than others. We can divide the associated problems of consciousness into "hard" and "easy" problems. The easy problems are explicable through the standard methods of cognitive science.

He coined the phrase ‘the hard problem of consciousness’ to describe the aspects of consciousness that current scientific methods cannot even explain in principle. His aim was to challenge neuroscientists who believe that their continued success in solving various 'easy' problems of consciousness means they will eventually solve all the problems of consciousness.

Property Dualism

Arguments against substance dualism have lead Philosophers to look at the alternative of Property Dualism. A property is a quality of a substance that depends for its existence on that substance. Property dualism claims that the world is constituted of just one kind of physical substance but that there are two ontologically distinct kinds of properties: physical properties and mental properties. The brain has a unique set of non-physical properties e.g. experiencing sensations, thinking, desiring. These mental properties are not reducible to matter or explained fully by science.

Some philosophers divide mental properties into two types:

Intentional states (which are about something) e.g. Bill's belief that sweets are edible and

Phenomenal/sensational states (what it is like to have something) e.g. what Bill's toothache feels like to him (This distinction is challenged by 'representationalists' who hold that phenomenal properties are intentional.)

For Property Dualists consciousness is a real phenomenon but it is not substantial i.e. it cannot exist without a living brain. Conscious experience emerges when the brain reaches a certain level of complexity. Mental properties are inherent in human brains. How mental and physical properties relate causally (or don’t in the case of Epiphenomenalism) depends on the variety of property dualism.

Epiphenomenalism

Epiphenomenalism is a form of property dualism that tries to accommodate the anti-materialist arguments about consciousness and the causal closure of the physical. In this view mental states do not have any influence on physical states. Physical events can cause other physical events and physical events can cause conscious events in our mind, but mental events cannot cause anything, since they are just causally inert by-products (i.e. epiphenomena) of the physical world. It may seem as if we are making things happen ‘out there’ in the physical world but this is an illusion, we are passengers in, rather than drivers of, our physical body. This view was first formulated by Thomas Henry Huxley and has been defended in recent times by Frank Jackson in his article Epiphenominal Qualia.

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Jackson introduces ‘Epiphenomenal Qualia’ by confessing to being a ‘qualia freak’; someone for whom it seems obvious that no amount of physical information can capture what it is like to ‘smell a rose’.

In Epiphenominal Qualia Jackson puts forward four arguments as to why Physicalism is false: the ‘basic argument’: Nothing you could tell of a physical sort captures the smell of a rose.

The Modal argument (a version of the Possible worlds/philosophical zombie argument)

The ‘What it is like to be argument’ based on “What is it like to be a bat?” by Thomas Nagel.

Nagel claims that no amount of physical information can tell us what it is like to be a bat, this can only be understood from a bat’s point of view, which is not something capturable in physical terms.

Jackson says that this is the same with other Human Beings, when we learn about someone else’s experience of say, colour, we are not finding out what it is like to be them. No amount of knowledge about another person, physical or not, amounts to ‘first person’ knowledge “from the inside”.

Jackson says that the major factor in stopping people from admitting qualia is the belief that they would have to be given a causal role with respect to the physical world and especially the brain (which Epiphenominalism doesn’t do).

The knowledge argument against Materialism: Fred and Mary

Fred has superior colour vision, he can distinguish between the red in ripe tomatoes (he can separate out two groups of wave-lengths in the red spectrum so that ‘red1’ from ‘red2’ appear as entirely different colours)

We are to Fred as a totally red-green colour-blind person is to us.

No amount of physical information about Fred’s brain and optical system tells us about his colour experience.

There is something about it we don’t know even though we have all the physical information.

Therefore, knowing all this is not knowing everything about Fred.

It follows that Physicalism leaves something out.

After a transplant of Fred’s optical system, we would know more about Fred’s colour experiences. But before we had all the physical information about his body and brain, as well as everything that has ever featured in physicalist accounts of mind and consciousness.

Mary is a brilliant neuroscientist. She knows all about which wavelengths of light produce which effects on the retina, and how this information is translated into excitations in the brain’s visual system and how this leads people to say they have had colour sensations.

However, she has lived all her life in a black and white room. When she leaves the room or is given a colour television monitor she learns something about the world and what it is like to see colour. So Jackson maintains that although she had all the physical information, her previous knowledge was incomplete.

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This can be formulated as follows:

1 Mary knows everything about the physical facts and processes involved in colour vision.

2 But on her release, she experiences colour vision herself and discovers what it’s like to see colour

3 Therefore, what it is like to see something red is not a physical property and so there is more to know about colour vision than what is given in a complete physical account of it.

4 Therefore, (at least some) facts are not physical.

So physicalism is false.

The same style of Knowledge argument could be employed for all qualia.

Criticisms of the knowledge argument

Mary gains no new propositional knowledge (just acquaintance knowledge) Having all physical knowledge would include knowledge of qualia (Churchland) There is more than one way of knowing the same physical fact Qualia do not exist so Mary gains no new propositional knowledge (Dennett)

Mary gains no new propositional knowledge

Paul Churchland argues that “the defect ... is simplicity itself”. Jackson is guilty of equivocation in using “knows” in two different ways and this renders the argument invalid. Even if we accept that Mary gains new knowledge when she sees red for the first time this doesn’t mean that she gains knowledge of a new fact or proposition, she gains ability knowledge (knowing how rather than knowing that) or ‘acquaintance knowledge’, a direct awareness of what it is like to see red.

If ‘what it is like to see red’ is a physical property of the visual experience that occurs in the brain (type identity), Mary can know all about what this physical property is like, when it occurs etc. before she leaves the room. However, she doesn’t have direct knowledge of it because her brain has never ‘known’ this property. When she sees red, this property occurs in her brain and she becomes acquainted with it. She gains new knowledge, but she hasn’t learned any new fact.

Lewis and Nemirow claim that on her release Mary acquires a certain representational or imaginative ability (e g. to re-create perceptual experiences of a certain kind her in imagination).

In ‘What Mary didn’t know’, Jackson says that this objection misunderstands his original argument against physicalism. His point wasn’t that Mary learns a new fact about red on being let out, but that even with all physical knowledge, her knowledge was still incomplete. He agrees that Mary will acquire new abilities after her experience of seeing red, she will, for example, be able to remember what seeing red is like. But the knowledge argument isn’t about Mary's experience, it is that Mary didn’t know everything about other people’s experience of red before she left the room, even though she knew everything physical about their experience. Mary didn’t know what it is like for anyone to experience red. This is a propositional fact that she acquires when she leaves the room. He summarises his position as follows:

(1) ' Mary (before her release) knows everything physical there is to know about other people.(2) ' Mary (before her release) does not know everything there is to know about other people (because she learns something about them on her release). Therefore,(3) ' There are truths about other people (and herself) which escape the physicalist story.

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The skeptical response is that as Mary cannot directly access anyone else’s subjective experience, she can’t know that their experiences resemble hers.

There is more than one way of knowing the same physical fact

Before leaving the room, Mary has a concept of red in physical terms - wavelengths of light, etc. We can contrast this ‘theoretical’ concept of red with a ‘phenomenal’ concept of red which Mary acquires when she sees red for the first time. She is now able to think about red in a new way, in terms of what it is like to see red. But, they are two different concepts of a physical property of the brain.

The knowledge argument doesn’t show that ‘what it is like to see red’ cannot be a physical property. So the argument fails to show that there are any non-physical properties or that physicalism is false.

Jackson may be guilty of the ‘masked man fallacy’, claiming that Mary knows what physical sensations of red are and what the qualia associated with red are and that they are not the same. What Mary may really gain is a new ‘subjective experience’ of redness, but not a new fact.

Jackson says that the intensionality of knowledge is not to the point. Mary knows all she can know logically, but her knowledge is incomplete.

All physical knowledge would include knowledge of qualia

The arguments above accept the claim that Mary learns something when she leaves the room. This objection denies this. Churchland’s criticism is that the argument works against itself. We don’t really know what knowing all the physical facts about colour would involve. It might be possible, to work out what experiencing colour is like. If Mary really did know everything about seeing red, she would not learn anything when she first sees red. The experience of seeing red is nothing more than highly detailed knowledge of what it is to see red that she already has. This objection claims that there is, in principle, a complete analysis of phenomenal properties in physical and functional terms.

This objection is counter-intuitive. It requires that Mary is able to work out what it is like to experience a colour without ever having seen one.

In ‘What Mary Didn’t Know’, Jackson says that Mary could imagine what it is like to see red before she leaves her room. Imagining something is not the same as knowing it. If Mary knows all the physical facts, and these were all the facts there are, she wouldn’t have to imagine it.

In his postscript to In ‘What Mary Didn’t Know’, Jackson claims that if physicalism is true we would be able to deduce all the facts about water from a complete physical description of H2O and we would be able to deduce all the facts about consciousness from a complete physical description of the brain. Until his change of mind he argues that this is an implausible claim.

Jackson then came to accept physicalism:

1. Assume that interactionist dualism is false.

2. Therefore, what causes our conscious experiences is purely physical (either physicalism is true or epiphenomenalist dualism is true).

3. Therefore, when Mary comes to learn what it is like to see red, this process has a purely physical causal explanation.

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4. Therefore, what Mary learns is also something physical - it can be understood and explained in purely physical (and functional) terms. We shouldn’t think that what she learns is something that doesn’t feature in the explanation of how she comes to learn it.

5. Therefore, we should reject epiphenomenalist dualism and accept physicalism.

Qualia (as defined) don't exist

The knowledge argument claims that phenomenal properties are ‘intrinsic and non-representational properties of experience’ (Qualia). The last objection rejects this understanding of phenomenal properties. There are no qualia. Phenomenal properties are, instead, just physical, functional properties.

We can us the principle of Ockham’s razor to reject the claim that phenomenal properties are qualia. Our explanation of the mind is simpler if we can explain phenomenal properties in terms of physical and functional properties. We need a really good reason to think that everything except consciousness can be explained in physical and functional terms.

Other problems facing Epiphenomenalist dualism

The causal redundancy of the mental

Epiphenomenal dualism claims that the mind has no causal powers.This is counter-intuitive since my experiences and sensations seem to make a difference to my thoughts and actions.

Jackson responds that although it seems obvious that the ‘hurtfulness of pain’ is responsible for someone saying ‘it hurts’ and seeking to avoid pain, it might be that the experience is just a ‘commentary’ on a physical process that has already occurred.

The argument from introspection

This objection is a version of the ‘problem of other minds’. It asks how a person’s behaviour can provide any reason for believing s/he has qualia, if it is not the outcome of qualia. I cannot gain knowledge of my mind from introspection since my beliefs about my mental states are not caused by the mind. It is strange to suggest that consciousness plays no causal role in my saying 'I am conscious'. It is often held that if a belief about X is to qualify as knowledge, the belief must be caused by X. But if consciousness does not affect physical states, and if beliefs are physically constituted, then consciousness cannot cause beliefs. My beliefs about my mind, therefore, are unreliable as I can’t ‘know my own mind’.

Jackson responds with the following argument:

I read in The Times that Spurs won.

Spurs’ winning is likely to be what caused the report in The Times.

Spurs' winning would have had many effects, including almost certainly a report in The Telegraph.

However, the report in the Times did not cause the report in the Telegraph

Jackson is arguing from one effect back to its cause and out again to another effect; the fact that neither effect causes the other is irrelevant. The Epiphenomenalist allows that qualia are effects of what goes on in the brain, but are not themselves causes of anything physical.

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Issues relating to free will and responsibility

Epiphenomenalism undermines free will and responsibility by saying that actions are effects of physiological processes in the brain. So called ‘choices’ are mental events without causal powers. If what I do is not caused by my own choice, I am not free in what I do.

Some interpretations of quantum mechanics claim that ‘not every event in the world is causally determined by previous physical events’. At the quantum level events are apparently random or ‘probabilistic’ rather than determined.

This suggestion has not been widely accepted, since it relies on the claim that the correct interpretation of quantum mechanics leaves room for genuine indeterminacy at the quantum level.

Evolution

According to natural selection the traits that evolve over time are those conducive to physical survival. We may assume that qualia evolved over time and so we should expect qualia to be conducive to survival. However, they do nothing to the physical world.

All we can expect is that any evolved characteristic is either conducive to survival itself or occur as a result of a physical characteristic that helps survival. The epiphenomenalist holds that qualia are a by-product of certain brain processes that are conducive to survival.

Jackson’s criticisms of Epiphenomenalism

In ‘Epiphenomenal Qualia’ Jackson tried to explain why it was still possible to be a dualist in a modern world, but he ‘came to think of this as a triumph of philosophical ingenuity over common sense’. When he thought of himself writing the paper, whilst not being caused to do so by the property of thinking about it, he found epiphenomenalism too hard to believe.

When he asked himself how we can remember red when not seeing red he concluded that memories are physical activities. He became sympathetic to Representational Realism, which maintains that when you have a colour experience, there is nothing coloured in your experience. So Mary has a representation of how things are, based on the physics of the relations between the objects themselves.

Jackson now calls himself ‘a card-carrying physicalist’. If asked how we can tell people are having similar experiences he cites common neuro-physical responses and information processing in the brain and similar behaviour.

The ‘philosophical zombies’ or conceivability argument for property dualism

David Chalmers has used the idea of ‘philosophical zombies’ to argue that 'no explanation given wholly in physical terms can ever account for the emergence of conscious experience'.

Philosophical zombies are identical to human beings in all physical (and functional) respects, but entirely bereft of phenomenal properties. They have normally-functioning human brains but no consciousness. They have all of the physical states, but none of the mental states. There is nothing 'it is like' to be the zombie, as the zombie has no experiences.

Because only our own mind is accessible through introspection we can never know whether someone else is a (philosophical) zombie or not or that everyone else is not a zombie (see the problem of other minds).

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Like Descartes’ conceivability argument the ‘zombie arguments’ starts from an epistemic claim and concludes with an ontological claim.

We can imagine that philosophical zombies exist since there is nothing contradictory in the idea

(Chalmers doesn’t think they actually exist in this world, it may even be physically impossible given the laws of nature which operate in the universe).

We can therefore conceive of physical properties existing without the phenomenal properties of consciousness in a ‘zombie world’. What we can coherently conceive of is possible

It is logically possible to have a world that explains all the physical facts without explaining facts about consciousness.

(If God could have created a zombie world, then after creating the physical processes in our world, he had to do more work to ensure that it contained consciousness)

Chalmers simplified the argument as follows:

(1) It is conceivable that there be zombies

(2) If it is conceivable that there be zombies, it is metaphysically possible that there be zombies.

(3) If it is metaphysically possible that there be zombies, then consciousness is non-physical.

(4) Consciousness is non-physical therefore materialism is false.

A more general and precise version of the argument appeals to P, the conjunction of all microphysical truths about the universe, and Q, an arbitrary phenomenal truth about the universe. (~ = not)

(1) It is conceivable that P&~Q.

(2) If it is conceivable that P&~Q, it is metaphysically possible that P&~Q.

(3) If it is metaphysically possible that P&~Q, then materialism is false.

(4) Materialism is false.

Problems with the conceivability argument

The essence of phenomenal properties is what it is like to experience them.

The essence of a physical property is its structure; and the essence of a functional property is what causes it and what it causes.

If phenomenal properties have a different essence from physical properties, each can exist without the other. So, zombies are possible.

If phenomenal properties are just physical and/or functional properties, then it isn’t possible for zombies to exist.

Monists either argue that ‘a zombie world’ is not conceivable (Chalmers calls this ‘type-A materialism’)

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OR they may argue that although it is conceivable, it is not in fact possible (‘Type-B materialism’)

The knowledge and zombie arguments begin from an epistemological claim and infer a metaphysical claim. Physicalists can object to either the epistemological claim or to the inference of a metaphysical conclusion.

A ‘zombie’ world is not conceivable

Against the epistemological claim, physicalists can argue that zombies are not, in fact, conceivable if we correctly understand consciousness. A physical duplicate of you is a functional duplicate of you and any functional duplicate of you must also have the same cause and so be conscious.

Consciousness cannot be completely analysed in physical and functional terms, as such an analysis cannot capture the intrinsic quality of conscious experience.

What is conceivable is not possible

Physicalists can also object to the metaphysical inference that if zombies are conceivable, they are possible.

We cannot assume that physicalism is false, since that is what the zombie argument is trying to prove (begging the question).

According to physicalism, everything that exists is either physical or depends on what is physical.

If consciousness is identical with physical properties, it is impossible for a creature to have the same physical properties but not have consciousness.

A world that is an exact physical duplicate of our world, with nothing else in addition, will be an exact duplicate of our world in all respects.

This argument can be summarised as follows:

1. A zombie is a physical duplicate of a person with phenomenal consciousness, but without phenomenal consciousness.

2. A physical duplicate is a functional duplicate.

3. Therefore, a zombie is a physical and functional duplicate of a person, but without phenomenal consciousness.

4. Phenomenal properties are physical properties realising particular functional roles.

5. Therefore, a physical and functional duplicate of a person with consciousness has phenomenal consciousness.

6. A physical and functional duplicate of a person with consciousness cannot both have and lack phenomenal consciousness.

7. Therefore, zombies are inconceivable.

Conceivability is not always a reliable guide to possibility. For example, we can conceive that water is not H2O, but this is not possible because H2O is the essence of water.Likewise, if phenomenal properties are physical properties, zombies are impossible.

Jackson argues that if physicalism is correct, then it must be possible to deduce all the facts about phenomenal properties from the facts about physical properties.

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Because H2O is the essence of water, which is why H2O without water is impossible.However, the essence of a phenomenal property is how it feels, not some physical property.So, it is metaphysically possible to have the physical property without the phenomenalProperty.

According to physicalism, there is no difference in principle, only a difference in complexity, between an amoeba and us. But to know all the physical and functional facts about an amoeba is to know all the facts about an amoeba. Because it is implausible to say the same about us, physicalism is false.

Descartes infers possibility from conceivability

The ‘masked man fallacy’ has been used to show that inference from what is conceivable (that zombies exist) to what is the case is illicit. (see glossary).

Chalmers version can be described as follows:

I experience my mental properties through introspection

It is conceivable that others do not have mental properties (they are zombies)

Therefore, my mental states and my body are not the same thing

Again, the fallacy lies in the jump from conceiving that ‘two’ people or things are distinct, to inferring that it is possible that they are distinct (or impossible that they are not).

What is logically possible tells us nothing about reality

This objection targets the inference from the claim that zombies are possible to the conclusion that property dualism is true. The zombie argument shows, at best, that in another possible world,physical properties and phenomenal properties are distinct.

This objection misunderstands the Physicalist claim that what exists is either physical or depends upon what is physical. In this case ‘depends upon’ means that if one property is identical then the other property cannot be different. (Leibniz’s principle of the indiscernibility of identicals).

For example, if two paintings are identical, then their aesthetic properties cannot be different. This applies to properties of consciousness as well.

According to physicalism, phenomenal properties cannot differ from physical properties.

The zombie argument and possible worlds

The zombie argument claims that there can be two worlds that are physically identical but with different phenomenal properties.This presumes that once the physical properties of a world are finalised, there is still further work to be done to ‘add’ consciousness.

To continue the analogy, the two concepts ‘water’ and ‘H2O’ are quite distinct and we could think that water and H2O could be different in some possible world. However if we do so we are not thinking clearly. Given that water is essentially H2O, it’s not metaphysically possible that water isn’t

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H2O.This is because the essential properties of something can’t change in different possible worlds, even if the contingent properties can.

If A is identical to B, then A and B are the same thing. It’s not possible for A to be B and for it not to be B.

A is identical to B is necessarily true, if true at all.

Therefore, it is true in all possible worlds.

According to physicalism, if a possible world has the same physical properties as this world, then all its properties are the same. In other words, if all the physical truths are the same in two worlds, then all the truths about phenomenal consciousness are the same. This means that there is not a possible world in which our premises (all the physical truths about the world) are true and the conclusion (some truth about phenomenal consciousness) is false.

If phenomenal properties are physical properties in this world, then they are physical properties in every possible world. And if they are not physical properties in another possible world, then they are not physical properties in any possible world, including the actual world.

Logical behaviourism

As zombies cannot be empirically distinguished from ordinary people claims that they exist is a nonsensical idea according to verificationists.

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Materialism

The alternative to substance dualism is the view that there is only one kind of substance, which is matter. The mind is not ‘ontologically distinct’ from what is material, but dependent upon it for its existence.

Physicalism

In recent years, materialism has been supplanted by ‘physicalism’. The reason for this is that physics has shown that ‘matter’ is too crude an identification of the most basic substance that exists; e.g. matter can be changed into energy.

we could define physicalism as the view that everything that exists is physical, or depends upon something that is physical. ‘Physical’ means something that comes under the laws of physics, and whose essential properties are identified and described by physics.

Physicalism says:

the properties identified by physics are ontologically ‘basic’ and form the fundamental nature of the universe. Other properties, in particular mental properties, are ontologically dependent on the properties identified by physics (or more broadly, the natural sciences)

physical laws govern all objects and events in space-time;every physical event has a sufficient physical cause that brings it about in accordance with the laws of physics. (This is known as the ‘completeness of physics’ or ‘causal closure’.)

No other, non-physical causes are necessary. If there are non-physical causes, they don’t contribute anything in addition to physical causes to the way the physical world changes over time.

Logical behaviourism

Logical behaviourism, also called ‘analytical’ behaviourism, is a form of physicalism, but it does not attempt to reduce mental states to physical properties directly. Instead, it analyses them in terms of behaviour.

The simplest form that logical behaviourism can take is to claim that a mental state just is actual behaviour; e.g. to believe something is just to say that you believe it, to be in pain is just to wince, shout, etc.

Logical behaviourists say that when we attribute a belief to someone, we are not describing a particular internal state but what s/he might do in a specific situation. This is termed an ‘analytic reduction', i.e statements about minds mean the same as statements about behaviour in the same way that ‘mother’ means the same as ‘female parent’.

Logical behaviourists maintain that since other minds cannot be observed, talk about them is either meaningless or reducible to what can be observed. Failure to recognise this, allowed dualists to become embroiled in ‘the pseudo-problem’ of other minds.

Behaviourism is compatible with the verification principle because statements about mental states are explained in terms of actual or possible behaviour and such statements are in principle verifiable.

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Arguments for logical behaviourism

The behaviourist position overcomes the problem of interaction as there is no causal interaction to account for.

We have access to the behaviour of others, and consequently that behaviour must be the basis for all our language about other people. If words acquire their meaning from the public context in which they are used, then there must be rules governing their use. This means it must be possible to determine whether they are being used correctly, but if mental-state terms get their meaning by reference to private experiences within each of our minds, it would be impossible to tell whether the words are being used correctly or not (see Wittgenstein on the argument from analogy).

The abandonment of the verification principle as a test for meaningfulness means that claims about mental states could be meaningful even if they are not explained in terms of observable behaviour.

Gilbert Ryle (1900 - 1976) The Concept of Mind (1945)

Influenced by Wittgenstein and the new linguistic philosophy. Used a largely behaviourist approach to refute substance dualism which he called the "dogma of the ghost in the machine".

His intention was to ‘explode the myth’ of Cartesian dualism and its associated problems.

Ryle didn’t think that a reduction of the language of mind to pure bodily movements was possible and for this reason is often called a ‘soft’ behaviourist.

Ryle identified the two main challenges Substance Dualism faces as the problem of causal interaction and the problem of other minds. He said that once we have clarified the proper ways in which the language of the mind is used in everyday discourse, these problems disappear.

Descartes starts from his own mind and his private mental concepts. Ryle agrees with Wittgenstein that to use mental concepts, we must talk and think about ‘the mind’ together.

Descartes thinks that the mind is a distinct unit or thing, but Ryle says that it is a distortion of language to make it mean "a distinct mental substance". Mind can only mean "what it is like to be me".

Observable behaviour is not sufficient to determine that a person is in pain. She could be acting (exhibiting pain behaviour without being in pain) or could be in pain without exhibiting pain behaviour (Super Spartans)

Ryle analyses mental states in terms of behaviour patterns or dispositions to act or react in certain ways, these sum up past behaviour in a law-like way and can be used to make predictions about future behavior. The same is true for beliefs. A belief is not a hidden state of mind that causes various behaviours, but someone’s tendency to do certain things.

Mental concepts behave differently from the way the dualist model supposes. They are not ‘occult causes and effects’ but what Ryle calls ‘inference tickets’ or ways of inferring future behaviour or of ‘forming hypotheses about persons’ likely behavior.

Ryle summarises the ‘official doctrine’ of Substance Dualism as follows:

1. The mind can exist without the body

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2. The body exists in space, subject to physical laws, while the mind does not 3. We are directly aware of our mental states through introspection, in such a way that we cannot make mistakes4. We have no direct access to other minds but can only infer their existence

He says that once science could claim that all physical, spatial processes could be explained in non-rational, mechanical terms, people drew the inference that mental terms must refer to non-spatial, non-mechanical states and processes. Ryle calls this the ‘para-mechanical hypothesis’. This reinforced the tendency to think of body as mechanical and mind as meta-physical.

Category Mistakes

Ryle says that Substance Dualism rests on a ‘category mistake’. He illustrates what he means with the following example: suppose someone is shown around Oxford University, and they ask: ‘I’ve seen the colleges, the faculties, the administration. But where is the university?’ They have misunderstood the concept of ‘university’, thinking that the university is another thing. But the university is not like this; it is how everything that the person has seen is organised.

Ryle argues, that this is what Descartes and other dualists are doing when they are looking for some special entity separate from the body and forms of behaviour called a "mind".

Dispositions

When we talk of someone having a certain mental state, we are talking of what they could do, or are liable to do, in particular situations, including conditions that they are not in at the moment.

Whether someone has a particular disposition is a matter of whether certain statements about what they would do are true or not. These are hypothetical or conditional statements of the form ‘if circumstances C occur, the person will do P.

Unlike ‘hard’ analytical behaviourists, Ryle does not think that statements using mental concepts, such as ‘he is proud’ can be completely ‘reduced’ to a series of hypothetical statements about behaviour. However dispositional statements justify certain inferences, explanations and predictions. To say that someone is proud licenses inferences about how he will behave in certain situations, but we cannot draw all possible inferences.

On Ryle’s analysis, dispositions are not causes.

Logical behaviourism is a form of physicalism because Dispositions depend on scientific facts - sugar’s disposition to dissolve depends on its physical properties, and our dispositions to behave as we do depend on our physical properties.

Thinking and mental processes

Ryle maintains that thinking isn’t a separate process from ‘doing’, although the thinking takes place in the mind and the doing in the physical world. Thinking ‘to oneself’ is internalised speaking. ‘Much of our ordinary thinking is conducted in internal monologue or ‘silent soliloquy’. Whether a process is public or private is irrelevant. ‘The phrase ‘‘in the mind” can and should always be dispensed with’. Mental processes only sometimes and only contingently take place ‘in the mind’.

Thinking is a mental ‘occurrence’ in the same way that something dissolving is a physical occurrence. From ‘it is dissolving’, we know that it is soluble. To say that someone is paying

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attention to what they are doing is ‘semi-hypothetical’ statement that both explains an actual occurrence and licenses inferences.

Criticisms of Logical Behaviourism

Denies that our mental states have an inner character, which is implausible.

Cannot account for our ‘privileged access to our own mental states’ and the fact that can know our own minds without having to examine our own behaviour or dispositions to behaviour.

Mental states can and do have no corresponding behaviour

We can, to some extent, control our behavior and we can conceive of mental states that have no accompanying behaviour. (Putnum’s Super Spartans)

The same mental state could be expressed in different behaviours (issue of multiple realisability).

Many mental states, such as knowledge, are dispositions, rather than occurrences.

The behaviourist analysis of mental terms is not clearly defined – it is vague

Any supposedly purely behavioural analysis presupposes ‘internal’ mental states. Describing behaviour at all is impossible without evoking such mental states. To say that an agent acted intentionally is to make implicit reference to a mental state. If the reduction is going to work it needs to completely eliminate all reference to mental states. Re-introducing the mind would mean that the argument was circular.

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Functionalism

Says that something is a mental state because it has a particular function.

Functionalism reduces mental properties to functional properties, defined in terms of their typical inputs and outputs (which may include other mental states).

The complete description of the mental state’s outputs, for each possible set of inputs, is what the mental state does.

Three kinds of relations constitute the essential features of a mental state:1) typical ways the environment (external and internal) causes the mental state2) typical ways the mental state interacts with other mental states3) typical ways the mental state, in conjunction with other mental states, causes behaviour

Consider pain:1) It is typically caused by bodily injury2) it causes distress, a desire to make it go away, a belief about the location of the injury, etc;3) and it typically causes, wincing, bad language, nursing of the injured area, etc.

Any state that plays this role is a pain.

Mental states are identified by the role they play, not by the physical properties of whichever brain state is realizing that role. There can be different brain states that have the same functional property. This may vary from one species to another. But as long as some state of the creature has the function that defines pain, then the creature is in pain. Sameness of mental state is sameness of causal role, not sameness of physical structure.

Many things are defined in terms of what their functions are e.g. the heart is something that pumps blood around the body of an organism: whether it’s made of muscle, or of metal and plastic is irrelevant.

Mental states depend upon causal physical states, so mental properties supervene on states of the brain. There can be no change in mental states without some change in the physical organisation of the brain. But because the physical material is not what defines a mental state, functionalism allows for multiple realisability.

Functionalism and Behaviourism

Functionalism can be seen as a development from Behaviourism but functionalists argue that mental states cannot be understood just in terms of behaviour because mental states often cause other mental states; e.g. pain normally causes the belief that one is in pain and the behaviour a mental state will cause depends on other mental states.

This avoids the objections to behaviourism discussed in circularity and multiple realisability of mental states. For functionalism, each mental state consists of a disposition to behave in particular ways and have certain other mental states, given certain inputs from the senses and certain other mental states.

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Types of Functionalism

Because functional properties can be realised by various physical (or even non-physical) properties, functionalism is compatible with substance dualism, although most functionalists are physicalists.

Functionalists have different views on the relationship between the brain and the function:

1) Any specific pain I have is identical to whatever in my brain (could be c fibres) is fulfilling the functional role of a pain-state for me at the moment (realizer functionalism).

2) Although my pain might be realized by a particular brain state at a particular time, it is not the case that my pain literally is that brain state. Mental states such as pain have a ‘higher-level’ relational property that is identified with the functional role itself, not with the brain state that occupies or ‘realizes’ that role.(role functionalism)

Analytic functionalism provides a “topic-neutral” analysis of our ordinary mental state terms or concepts. Any analytic functional “theory” can include only generalizations about mental states, their environmental causes, and their joint effects on behavior.

Causal role functionalism interprets ‘function’ as the role played in a network of causes and effects. A mental state causes other mental states, which together cause behaviour. A mental state can be ‘realised’ by any state that plays that causal role.

Holistic functionalism defines all mental terms at once in terms of the whole causal network of inputs, outputs, and internal states whereas a molecular functionalism defines mental terms in independent clusters.

Psycho-functionalism derives primarily from the methodology of “cognitive” psychological theories. Cognitive psychologists argue that the best empirical theories of behaviour take it to be the result of a complex of mental states and processes.

Teleological functionalism The causal role which identifies each mental state is defined in terms of the purpose of that mental state. For example, the function of pain can be described in terms of being caused by bodily damage, and causing certain other mental states and actions; this is what pain is for. So pain has an ‘evolutionary purpose’ for human development. Teleo-functionalism has been associated with the work of Daniel Dennett.

There are other forms of functionalism that understand functions non-causally, in a very similar way to how Ryle understands dispositions. A functional property is just a matter of whether certain hypothetical statements are true about it or not, and whether we can explain and predict behaviour using such statements. These forms of functionalism do not make any claims about ‘inner’ states that correspond to the functions we identify.

Machine Functionalism is based on the analogy between computer systems and the operations of the mind. Computers receive inputs, react by following a series of rules, and produce an output. Living organisms process sensory inputs and convert them into behavioural outputs. This suggests a further analogy between the computer hardware and our brain and the software and mental functioning or thinking. Human brains are understood as a complex system of inputs and outputs, the inputs being sensory and the outputs behavioural. We can describe the operations of such a machine in a diagram called a machine table. A machine table specifies which inputs will produce which outputs and the changes in internal states that affect them. Machine functionalists believe

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that each mental state can be identified as a particular state which a Turing machine (see below) might be in.

Non-machine functionalists take a non-reductive stance. They say that mental states cannot be modelled by anything as simple as tables which give ‘computational’ rules producing a pre-determined output. ‘Higher-level’ talk about mental states in terms of their function cannot be translated into, ‘lower-level’ talk about physical states of the brain without loss of explanatory power. A mental state can only be defined in terms of its relations to other mental states. This approach allows that a person may be in more than one mental state at one time.

Turing Machines (Alan Turing)

The classic example of something that can be ‘multiply realized’ is a computer program. The same set of instructions can be encoded in different programming languages, and followed by computers of different kinds. All computers follow sets of instructions which tell them what to do next, based on what state they’re in, and what input they are receiving. This idea of a computer as a rule-following machine was developed by Alan Turing in 1936, and people describe any machine which follows rules in the way he described as a ‘Turing Machine’.

A Turing Machine is a machine (that can be realized in multiple forms) that reads a tape divided into cells. A scanner-printer (head) reads the symbols that are written in the cells, one cell at a time and can erase what is in the cell, and write something new. A finite set of machine states tell the head what to do when it reads the symbol in a cell. For example, a machine can take a number and add ‘1’ to it. The machine's alphabet is ‘0’and ‘1’, and we can represent numbers as collections of 1s: 1=1,11=2,111=3, etc. Ned Block gave the example of a Cola machine that is programmed in this way.

Functionalists do not generally claim that simple machines of this sort have mental states, but the internal states specified by the machine table are analogous to mental states in human beings so that, in principle at least, a machine table could be written specifying the functions of a human being in response to the range of possible inputs it might encounter. The machine table for a human being would be an incredibly complex system composed of serially nested subsystems.

Hilary Putnam and others don’t consider humans to be deterministic automatons like the vending machine, but probabilistic i.e. it is likely that we will change into certain states or produce certain outputs in response to a specific input. As Turing Machines are multiply realizable, the software involved can be implemented in other kinds of hardware so that anything that runs the same program would have the same state. In the analogy, the same is true of human brains so that mental states are multiply realizable. Circularity

Functionalism is susceptible to the charge of circularity. We can’t define mental state M1 without invoking M2, but we can't define M2 without invoking M1. Our analysis of beliefs will say something about sensory input and the relation of the belief to other mental states such as desires. We can’t understand beliefs without invoking desires and we can’t understand desires without invoking beliefs.The same is true of Turing Machines; the machine state is defined in relations to inputs, outputs, and other machine states. However, this circularity in defining the states of a Turing Machine doesn't cause any problems (it is not a vicious cycle).

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The Turing Test

Alan Turing suggested a test of whether an artificial intelligence (A.I.) could be said to have a mind (including beliefs and other intentional states). If a computer could communicate with a human being in such a way that the human being could not tell the difference between conversing with the computer and conversing with another Human Being then it would have passed the test.

In support of the view that computers already have minds machine functionalists point to our ordinary (folk psychology) understanding of their basic operations. We say that a computer has ‘memory’, that it processes information, uses language, calculates, obeys commands, follows rules etc.

John Searle opposes the machine functionalist claim that organic brains are not required for consciousness. Mental states are essentially natural phenomena in the same way as other biological functions and they need a certain neurophysiology, i.e. a living brain, in order to be conscious.

The Chinese Room Argument (John Searle)

The argument aims to show that a computer which was functionally equivalent to a human being with respect to linguistic behaviour, and so could pass the Turing test, still wouldn’t be conscious.You're locked in a room, with two slots to the outside world marked “in” and “out".In the room, there are boxes of Chinese symbols, and a rule book containing instructions.Through the in-slot, people pass you Chinese symbols (in fact, these are coherent Chinese sentences).You look up the symbols in the rule-book, and it tells you which symbols to give back through the out-slot (these are perfectly coherent replies).

The Chinese Room is a computer that simulates understanding of ChineseThe boxes of symbols are the databaseThe rule book is the programYou are the hardware implementing the program(note that the inputs and outputs are the same as if there was somebody in the room who did understand Chinese)

Searle maintains that understanding a language requires more than manipulating symbols, it needs you to understand the meaning of what you are saying or writing. Merely implementing the right program does not in itself generate understanding (semantics). You have only simulated understanding of Chinese, not replicated it

(P1) Programs are entirely syntactical (P2) Minds have semantics(P3) Syntax is not sufficient for semantics(C) Minds are not just programs

(Syntax is about the form of symbols and the rules of grammar, Semantics is about the meaning we construct from those rules.)

Searle’s Chinese room argument focuses on intentionality, the feature of our mental states which enables them to be about things. He distinguishes different sorts of intentionality: as-if intentionality is possessed by things like rivers as they flow towards the sea, this is how we

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represent the river, but is not something possessed by the river itself. Intrinsic intentionality is only possessed by minds. Although they can pass the ‘Turing test’ computers do not have intrinsic intentionality. Like the person in the room, a computer only has as-if intentionality.Note: Searle does not argue that it’s impossible for e.g. computers made of silicon chips to have minds, all he’s saying is that they can’t have minds merely in virtue of whatever programs they’re running.

Systems Response

The person in the room doesn’t understand Chinese but the person is part of a system (symbols, rule book etc.) and the system as a whole could pass the Turing test. We attribute understanding not to the individual (neuron) but to the entire room (brain)

Searle’s response

The person in the room doesn’t understand Chinese because s/he doesn’t possess intentionality and has no way to attach meaning to the symbols. If one person has no way to attach meaning to the symbols, the room as a whole has no way to do this.

Searle suggests an extension to the thought experiment: imagine the person in the room memorizes the database and the rule book, s/he goes out and converses with people face-to-face in Chinesebut still doesn’t understand Chinese, because all s/he's doing is manipulating symbols

Paul & Patricia Churchland parody Searle's argument with The Luminous Room

P1) Electricity and magnetism are forces:P2) Luminance is a property of light;P3) Forces are not sufficient for luminance;C) Light is not just electromagnetism.

Moving a magnet up and down quickly, generates electromagnetic wavesIf electromagnetic waves in themselves are sufficient for luminance, this will produce luminance but this is absurd because you can't produce light merely by producing the right forces

Intuition is unreliable

Chinese brain thought experiment appeals to our intuition that the system cannot be consciousBut they could be wrong, when we are used to more complex machines, that talk and behave as we do, we may find our intuitions change. Stephen Pinker asks us to imagine a race of intelligent aliens with silicon-brains, who cannot believe that humans are conscious because our brains are made of meat.

The only basis we have for ascribing minds to others is that they behave appropriately, if we are happy to ascribe mentality to other humans we should be happy to do so to a machine capable of behaving in the same way. Any other attitude would be chauvinistic.

Syntax is observer-relative (John Searle)

Things like Gravitation, mass, etc. are intrinsic features of the world that would exist whether or not there are any observers.

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Other things are observer-relative: e.g. it being a nice day for a picnicThe things going on in a computer only have a syntax because we assign a syntax to them.A wall contains billions of molecules all moving in various ways, some of them may form a pattern of movement that is functionally identical to the structure of e.g. a word processing program. No one would argue that walls are word processors, because it's impossible for us to use them in that way, but in principle we could assign those same syntactical properties to any sufficiently large object.

Nothing has syntactic properties intrinsically. The idea that the brain is a computer and the mind a program tells us nothing about how the brain and the mind really work.

Functions are observer-relative

Functionalists say that if something performs the function of a heart, whether it’s made out of muscle or metal and plastic is irrelevant. However, an artificial heart is not the same as a biological heart. An artificial heart is a heart in virtue of our intentions for it; to pump blood around the body butwe could describe a different functional of the heart e.g. to make a rhythmic sound.

When we describe the function of something, there is always a normative judgement involved.This means that the existence of functions presupposes mentality and so cannot be used to explain it without circularity. This also begs the question of whether a defective heart is still a heart.

The functionalist may say that what makes something a heart is that it was selected to pump bloodBut appealing to natural selection only works if the trait in question was in fact selected.Many biological traits were not selected but are by-products of other things that they were selected.To define something according to its functional role we have to establish that this is what it was selected for. Something as complex as brain will have lots of by-products. Chomsky claims that our ability to use language is one of them.

We are in search of some ‘mysterious property’ if we insist the machine must possess supposedly intrinsic intentionality to have a ‘mind’. It’s not obvious that any theory of mind is able to explain this feature of consciousness. We can deny that anything – computer, Chinese room or human being – possesses intrinsic intentionality, perhaps the only kind of intentionality is the ‘as-if’ kind, this is just a way of interpreting and predicting human behaviour that is ultimately reducible to a set of causal relations.

More criticisms of Functionalism

Qualia

Qualia are ‘phenomenal properties’, they are what give an experience its distinctive quality e.g. ‘what it is like’ to experience redness or to smell a rose. We are aware of these properties through consciousness and introspection.

1. Qualia, by definition, are intrinsic, non-representational properties of conscious mental states.2. Intrinsic, non-representational properties cannot, by definition, be completely analysed in terms of their causal roles, because causal roles are relational properties, not intrinsic properties3. Therefore, if qualia exist, some mental properties cannot be analysed in terms of their causal roles.4. Functionalism claims that all mental properties are functional properties which can be completely analysed in terms of their causal roles.

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5. Therefore, if qualia exist, functionalism is false.6. Qualia exist.7. Therefore, functionalism is false.

Dennett claims ‘there simply are no qualia at all.’ If someone who woke up one day experiencing the world as coloured in a completely different way, s/he would not be able to tell whether

(i) their qualia were different from the ones they had had before or (ii) they were mis-remembering what their qualia used to be like.

Since the concept of qualia is of no practical use in describing situations like these, Dennett concludes that the concept itself should be abandoned.

Absent Qualia

In ‘Troubles with functionalism’ Ned Block accuses functionalism of ‘liberalism’ - the tendency to ascribe minds to things that do not have them. He questions the possibility of a functional duplicate with no qualia.

He outlines two systems which could be functionally equivalent to a human being but without mental states:

Imagine a body like yours with the head hollowed out and replaced with a set of tiny people who realise the same machine table as you; according to the functionalist account, this ‘homunculi-head’ (i.e. head full of people) would have a mind and experiences of pain and intentional states such as beliefs and desires. Block argues that such a system would not be minded as ‘there is nothing it is like to be’ the homunculi-head.

However, no physical mechanism seems very intuitively plausible as a seat of qualia, not even a brain.

Chinese Brain/Mind

Imagine that a human body is connected up to the whole population of China. Each Chinese person plays the functional role of a neuron in the brain (Block picks China because the population of China is roughly equal to the number of neurons in the brain). The Chinese are linked up to each other by two-way radios, and some of these are linked up to the input and output nerves of the body. Then the Chinese population recreates the functioning of your brain.

According to functionalism, this should create a mind; but it is very difficult to believe that there would be a ‘Chinese consciousness’. If the Chinese system replicated the state of my brain when I feel pain, would something be in pain and if so what? The Chinese system, although it duplicates your functioning, can’t duplicate your mind, because some mental states are qualia, and qualia are not functional states. This is one version of the absent qualia problem.

Inverted Qualia

This version of the objection is known as the ‘inverted qualia’ or the ‘inverted spectrum’ thought experiment. Suppose someone has an inverted experience of colour: his vision seems to work in the same way as yours, but where you see a green pigment, he sees red i.e. ‘what it’s like for you to see red’ and ‘what it’s like for him to see green’ are functionally identical and both have the same

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inputs (grass) and outputs (e.g. saying ‘grass is green’). Although the functionalist would say that you have the same mental states, you don’t because his inner experiences are not identical in terms of their intrinsic properties (qualia).

One functionalist response to this argument is to claim that, as a matter of scientific fact, or nomological necessity, sameness of functional organization does entail sameness of qualia. Mental states are the products of the particular physical states that constitute them, something without the same neurobiology would not be functionally equivalent. There may be some as-yet-undiscovered scientific law which guarantees that if somebody is really functionally equivalent to you, they necessarily have the same qualia as you. Thus inverted qualia could be described as empirically impossible.

Some philosophers will object that this misses the point: even if (as it happens) the laws of nature rule out inverted spectra in this universe, all we need to show is that it is logically or metaphysically possible for some creature to be in the same functional state as us but with different qualia, to establish that sameness of functional state does not guarantee sameness of experience.

In addition, this response sounds more like type identity theory and means that qualia are not multiply realizable.

Also, inverted colour qualia do seem to be a serious empirical possibility in pseudonormal vision.

We can modify the thought experiment so that it is specific to functionalism. If I was born with normal vision, but had an operation to switch the neural pathways from the optic nerve to the visual cortex, my qualia would be inverted. I would learn colour vocabulary and become fully functionally equivalent to you, but again my inner experiences would not identical to yours. This suggests that there is more to qualia than what can be captured by a functionalist account.

If spectrum inversion is conceivable, functionalism must be false. It is conceivable because qualia have intrinsic qualities, regardless of how they relate to other mental states or to sensory inputs and behavioural outputs.

If the hypothesis is both irrefutable and unconfirmable, logical positivism would be inclined to conclude that the idea of inverted qualia is nonsensical.

Functionalists can still claim that if we react in similar and complex ways to the same stimuli and if qualia play the same complex role in relation to other mental states and behaviour, this is all we need to be sure that we are in the same mental state.

Some functionalists concede that in this version of the thought experiment, the intrinsic physical differences would produce a different qualitative feel, and so concede that qualia cannot be given a complete functional definition.

However, functionalists need not give up on the theory as an account of most of our mental states such as beliefs and desires.

David Chalmers paper ‘Absent Qualia, Fading Qualia, Dancing Qualia’ argued for "the principle of organizational invariance”. This said that if a system has conscious experiences, then any other system with the same fine-grained functional organization will have qualitatively identical experiences i.e. if a system of computer chips reproduces the functional organization of the brain, it will also reproduce the qualia associated with the brain. If there are Absent Qualia or Inverted

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Qualia then this must be due to some non-organizational property and organizational invariance is wrong. "Fading and Dancing Qualia” are both reductio arguments which challenge the possibility of absent or inverted Qualia.

Fading Qualia assume that Absent Qualia are possible. We can imagine a continuum from Me with full experience to a Robot with none. The robot is a functional isomorph but is not conscious. This has been brought about by a process of gradual neural replacement. i.e. neurons have been replaced by silicon chips. We can take some midpoint on the continuum and call it Joe. Either Joe’s consciousness is fading slowly as the replacement takes place i.e. he sees muted colour or he hears muted sound (fading Qualia) or he loses consciousness at some point (suddenly disappearing Qualia).Chalmers argues that neither answer is satisfactory; such brutal discontinuities (disappearing Qualia) are not present elsewhere in nature and Fading Qualia would mean that Joe is systematically wrong about everything he experiences e.g. he sees red but experiences pink. However we know that when a conscious being has experiences it can form reasonable judgments about those experiences. If Fading or absent qualia are incomprehensible, Joe and the robot are as conscious as me. If that is true then all other functioning Isomorphs or whatever shape size and composition are conscious.

Dancing Qualia is a variation of Fading Qualia. It requires two visual processing systems with the same functional organization but different associated visual phenomenology and the capacity to switch swiftly between these systems. Since the functional organization of the systems is the same there will be no difference in experience when you switch from one to the other therefore, by reductio, the systems cannot really differ in their associated visual phenomenology.

The Inverted Qualia situation would be that I experience the colour red while my isomorph would experience the colour blue. We would both be conscious. Now assume that a silicon system identical to the isomorphs has been put in my brain as a back up system. There is a switch to allow me to switch between normal neurons and silicon replacements. If I switch between one state and the other then my experience of colour will change from red to blue and if the switch is switched rapidly the qualia will dance. However although my experience changes my behaviour doesn’t; this makes inverted qualia implausible.

ConclusionIf absent qualia are possible then fading qualia are possibleIf inverted qualia are possible then dancing qualia are possibleIt is implausible that fading and dancing qualia are possibleIt is therefore extremely implausible that absent and inverted qualia are possibleIt follows that we have good reason to believe that the principle of organizational invariance is true and that functional organization fully determines conscious experience.It follows that systems that duplicate our functional organization will be conscious even if they are made of silicon, constructed out of water pipes or instantiated in an entire population.

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Mind-Brain Type Identity Theory

Also known as reductive physicalism or type physicalism

Developed by I.T. PIace, Herbert Feigl and J.J.C. Smart

The theory is called ‘type’ identity, because it claims that mental ‘types’ of thing (mental properties, states and events) are the same type of ‘thing’ as physical ‘things’; i.e. mental properties are actually physical properties of the brain and mental states are brain states.

Facts about the mind are reducible to physical facts about the brain, pains, beliefs, desires etc. are ‘nothing but’ neurological (i.e. brain) states e.g. "pain” and "the firing of C-fibres” both refer to the same thing (compare with “water is H20").

For any type of mental state M, there is some type of brain state B such that M and B are numerically and qualitatively identical. (Qualitative identity means that things share the same qualities, numerical identity means they are ‘one and the same thing’).

Reductionism

Type identity theory is an ‘ontological reduction’, it involves the claim that two distinct mental and physical concepts (mind and brain) refer to the same property.

However, the concepts ‘pain’ and ‘the firing of nociceptors’ remain distinct although both refer to the same thing. This is because we have different ways of knowing about these properties. When we describe a brain state i.e. certain neurons firing in my brain, we are not saying the same thing as when we say we are experiencing pain, even if the source is identical. There are two concepts, but one property.

Identity theorists understood identity in slightly different ways. For Place, higher-level mental events are composed out of lower-level physical events and will eventually be analytically reduced to these. So, to the objection that "sensations" do not mean the same thing as "mental processes", Place could reply with the example that "lightning" does not mean the same thing as "electrical discharge" since we determine that something is lightning by looking and seeing it, whereas we determine that something is an electrical discharge through experimentation and testing. Nevertheless, "lightning is an electrical discharge" is true, since the one is composed of the other. For Feigl and Smart, identity referred to descriptions of the same thing, as in "the morning star" and "the evening star" both referring to Venus. Their response to the objection above, was to say that "sensations" and "brain" processes do indeed mean different things but they refer to the same physical phenomenon.

Other kinds of Identity Theory

“Central state materialism” requires that mental states are limited to the brain or the Central Nervous System, however some theorists include the Peripheral Nervous System in our identities.

A technical distinction is also made between 'types' and 'tokens'.

A type is a general class and a token is a particular instance of that class.

Type-type theory says that every type of mental state, e.g. seeing red, is identical with a particular type of brain state. Seeing red occurs if and only if there is particular neural activity in the visual cortex of the brain.

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The Type-token approach maintains that there is one type of mental state, e.g. seeing red, and many tokens of the type. For example, Frank will see red (normal human colour vision), John will see red (colour-blind colour vision) and Henry (the dog) will see red (black and white vision). In this example, there is one type of mental state, and three tokens of the type. Frank, Henry and John can all experience the same mental state (seeing red, pain etc.) even though it is identified with a different physical or ‘brain’ states in each case. Martians and computers could also have the same type of experience.

The token-token approach says that a particular mental state is caused by an identical physical state in that individual. Each token mental state is identical with a token brain event, although there is no type-type identity between species or individuals. Frank, John’s Henry’s, Martians and computer’s experience of seeing red or being in pain is different but is identified with a corresponding mental state in each individual.

Benefits of Identity Theory

The evidence of real-time imaging techniques shows that specific mental activities such as doing mental arithmetic, imagining performing an activity, recalling an event from the past etc., correlate with specific areas of the brain becoming active.

It is to be preferred on the grounds of simplicity (Ockham’s razor), it does away with ‘nomological danglers’ (see below).

At present, we do not know enough about the workings of the brain to say exactly what mental states are but identity theory is confident that we will eventually be able to reduce concepts from folk-psychology to neurological activity.

Ockham’s Razor

Ockham’s razor says that, given two competing hypotheses, if their explanatory power is equal, then the simpler one should be preferred. Also, that we should not ‘multiply causes’. If we can explain mental states in terms of the brain and dualism has no explanatory advantage, a physicalist account should be preferred.

Nomological danglers

Smart says that non-physical states of consciousness would be ‘nomological danglers’ that don’t fit into the system of scientific laws which govern everything else in the universe. The reduction of the mind by neuroscience would continue the scientific trend applied to states of matter, sound, electromagnetic phenomena etc.

Objections to the Identity Theory

As far as philosophy is concerned, the mind could be any bodily organ (like the pineal gland).

Identity theory cannot be demonstrated a priori by philosophical analysis of language. When we say ‘pain is a C-fibre firing in the brain’ we are not making an analytic statement (i.e. true by definition) but an empirical one. Neuroscientific evidence can demonstrate correlations between mental and physical properties, but this does not establish the type identity theory.

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Identity Theory puts forward the scientific hypothesis that the terms brain and mind refer to the same object in this world, but this need not be the case in ‘all possible worlds’. A contingent identity (rather than a necessary one) between mental states and brain states means that it is conceivable that mental states could be realised in a different way.

Problems with each form of Identity Theory

Type-type theory

Some very different moods have a lot in common (fear and excitement, for instance). This suggests that, even if brain states are mental states, happy states might correspond to a range of different brain states.

The next problem concerns how we can be sure that the same mental states produce the same brain states in other people. This is known as the benchmark problem and is responsible for a refinement called Token Identity Theory. 

Type-token theory

Token Identity Theory is even more open to the benchmark argument, in fact, there is no benchmark at all, because every person’s brain activity is unique. It is also possible that similar types of behaviour do not correspond to any particular mental state.

Token-token theory

It is difficult to determine where type identity ends and token identities begin. Quine gives the example of country gardens where the tops of hedges are cut into various shapes, for example the shape of an elf. We can make generalizations over the type elf-shaped hedge only if we abstract away from the concrete details of the individual twigs and branches of each hedge. So, whether we say that two things are of the same type or are tokens of the same type because of subtle differences is just a matter of description.

We also have the problem that no brain activity need correspond to any sort of mental state or behaviour whatsoever. This cannot even be tested for, since it may be argued that we can never have the same thought twice and therefore never have the same brain state twice.

Physicalist Objections

Identity Theory cannot account for the unity of experience

A single state of consciousness includes many distinct experiences. Brain activity takes place in different locations. There does not appear to be a "neurological central processing unit”.

We can have brain states without their corresponding mental states

Suppose we construct an exact replica of the C-fibre system and leave out everything else in our brain, then we stimulate the disembodied C-fibres. Would this system experience pain?

In order to have any mental states at all, we need a more complex system, like a whole brain.

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Multiple Realisability

In Psychological Predicates Putnam argues that mental properties are not identical to physical properties because the same mental property can be related to different physical properties. For example, a variety of creatures seem to have mental states e g. being in pain. If all these creatures have pains, there must be some neural state that all these creatures share when they're in pain, however the brain states that relate to pain may be different in different species. Therefore, ‘being in pain’ cannot be exactly the same thing as having a particular physical property.

If there are aliens and they have mental states, it is extremely unlikely that they will have the same physical states as us, we may also build conscious computers with different physical structure, that could experience pain.

There is evidence that mental states are ‘multiply realizable’ even among different members of the same species. A feature of the human brain is its plasticity i.e. different parts of the brain are capable of adapting to perform different functions if required.

Type-type theory seems plausible for seeing colours which has a straightforward neurophysiological basis, common to all human brains. If the visual cortex was damaged, we would cease to be able to see red. It is less plausible for other states of mind, such as beliefs or desires. These may not be caused by the same type of brain state either between different individuals or even in the same individual at different times.

The multiple realisibility argument could be rephrased as an a priori conceivability argument. Even though pain in humans is correlated with brain state A, it could have been the case (in some other possible world) that pain was correlated with brain state B and this would be enough to show that pain is not identical with brain state A.

1. It is conceivable, for a being with a different physical constitution from us to have the same thoughts or sensations

2. It is therefore possible for a being with a different physical constitution from us to have the same thoughts or sensations

Followed by an indivisibility argument:

(P1) All mental states are multiply realisable by distinct physical states

(P2) If a mental state is multiply realizably by distinct physical states, then it cannot be identical to any specific physical state

(C) No mental state is identical to any specific physical state

Kripke rejects the notion of contingent identity, saying that any identity-claim between pain and a particular brain-state must hold ‘in all possible worlds’.

If the claim Token identity-theorists are making is merely that ‘pain for humans’ is identical with brain state A, it doesn’t matter that there are (or might be) other creatures whose ‘pain’ is correlated with different kinds of brain state, although this tells us nothing about what it is about states A and B that makes them both pain states.

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The chauvinism of type-type identity theory

Type-type identity theory is chauvinistic because it withholds mental properties from beings that may have them and claims that human beings are the only possessors of mental states. This goes against our intuition about animal mentality and our sense that if a creature behaves as though it is in pain, it should be judged to be in pain regardless of what kind of a brain it has.

Supervenence

Mental states are said to ‘supervene’ on brain states if they depend on brain states for their existence and if there can be no changes in mental states without corresponding changes in brain states.

Those who believe that the mental is supervenient on the brain claim different things can be going on in the brain to produce the same mental event, in other words, mental states are multiply realizable.

Domain-specificity

David Lewis says that reductions are often carried out relative to a particular domain. If we accept domain-specificity, we need no longer claim that pain-in-humans and pain in-Martians are the same thing.

To maintain the domain-specificity line, we are driven to saying things like: The physical realisation of pain-in-Frank is x, the physical realisation of pain-in-John is y, the physical realisation of pain-in-Henry is z. There may be as many realisations, as there are individuals.

Token Identity

In response to multiple realisability, physicalists draw on the type/token distinction. In type token identity different creatures can have different kinds of brain and brain states which are identical with the same type of mental state that we experience. Token identity theory talks about ‘human pain’ or ‘animal pain’ or ‘alien pain’ all of which are examples of the mental state of ‘being in pain’.

A difficulty with this is that we now have as many different types of pain as there are creatures with brains. If each type of brain has its own type of pain, we have no way of specifying what it is about these different brain states that makes them all pains.

If the only answer is that creatures in these states act as though they are in pain, we seem to have retreated to a behaviourist definition of pain and abandoned the effort to identify it neuro-physiologically.

Folk Psychology

Someone who has no knowledge of the brain can still speak meaningfully about his or her mental states. The ‘illiterate peasant’ using the vocabulary of folk psychology; knows what he means by ‘pain’.

Putnam develops this point by saying that the statement ‘pain is a brain state' is implausible since the words we use to talk about our mental states and processes do not mean the same as our vocabulary of physical brain states. Any reduction of folk-psychological talk to talk about brain states will change the meaning of the terms.

Smart says we can talk about lightning without knowing anything about electrical discharge because the concepts are distinct. That doesn’t show that lightning isn’t electrical discharge. The same is

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true of ‘sensation’ and ‘brain process’. The physical realization of mental states can be very different from the source, but that doesn’t mean they are not the same thing.

Meaning and reference

There is a philosophical distinction between 'meaning' and ‘reference’

The meaning of a term or phrase is the way the thing it identifies is conceived to the ‘mind’

The reference is the actual thing in the world to which the term refers

It is quite possible for two terms which have different meanings to have the same reference

Identity theorists accept that our vocabularies for mental and physical states have different meanings, although they still refer to the same things.

The spatial location problem

The location problem raises the objection that brain states have specific spatial locations and relationships to other physical states whilst mental states do not have spatial location, size or shape.

If we can identify a property of mental states that brain states don’t have, the identity theory would be refuted by Leibniz’s principle of the indiscernibility of identicals:

1. If mental states are identical to brain states, then they must share all their properties in common

2. Brain states have a precise spatial location, and stand in spatial relations to other spatial locations and other physical objects

3. Mental states are not located in space in the same way

4. Therefore, mental states are not brain states

Putnam considered this objection in ‘Psychological predicates’. For one phenomenon to be reduced to another, they have to occupy the same spatial location, but a pain in the arm and a brain state are in different spatial locations.

Putnam then dismisses this objection on the grounds that the principle that the two phenomena must occupy the same space is not sound. He uses the example of a mirror image. In the same way, the apparent location of pains in parts of the body doesn’t mean that they are not in fact brain states (see theories of perception). A belief or a desire may be a condition realised in someone’s brain. Some mental states cannot be given precise shapes and sizes but they do take place where the person having them is and so do have spatial characteristics.

In Sensations and Brain Processes Smart says that the objection ‘begs the question’. If mental states are brain states, then they do have a spatial location and we should add to our current grammatical rules to allow us to talk of experiences in spatial terms.

Ryle would object that Smart’s solution involves a category mistake. It is not ‘merely’ a linguistic convention that we don’t talk about the spatial location of thoughts or visual experiences. There is a correlation between a particular mental state and a brain state that has a spatial location but this doesn’t show that the mental state itself is spatially located.

Identity theory claims that we should change our understanding of what ‘makes sense’ on the basis of scientific discoveries and that the correlation between mental states and brain states is best explained by their identity.

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Identity theorists accept the metaphysical possibility that someone could be in pain without their C-fibres firing, but insists that, as a matter of empirical fact, it never happens. If it did this would disprove the theory.

The identity being argued for is contingent, in which two apparently distinct entities turn out to be the same thing. If two apparently distinct things are numerically identical there is no sense in which they could be distinct. If it is the case that water is H20, then it is not possible, and never was possible, for water not be H20, there is no possible world in which water turns out to have a different molecular structure. The identity between mind and brain can only be a necessary identity even though it is discoverable through empirical means. In which case it would be logically impossible for the mind not to be the brain, and so impossible to conceive of brainless aliens.

Dualist objections

1) Mental states appear to have different properties to physical states

If you look at a red car, you will experience red, an experience of red is not itself red so your experience of red is not identical with your brain state.

This objection is based on a simple confusion. We shouldn’t confuse the properties of the experience with the properties of the objects being experienced. (U.T.PIace called this confusion the “phenomenological fallacy").

The Divisibility argument

Descartes says that the mind cannot be identical to the brain because the mind is not divisible while the brain is. He assumes that the mind is a ‘thing’ which can be divisible. This begs the question against the type identity theory, which maintains that the ‘mind’ should be understood in terms of mental properties possessed by the brain.

There are many properties that it does not make sense to talk of as spatially divisible e.g. the brain has a physical temperature of 35 degrees Celsius. So even if mental properties are not spatially divisible, they could still be identical with physical properties of the brain.

Identity theory cannot account for qualia

Philosophical zombies (David Chalmers) are physiologically indistinguishable from humans, but without mental states.

Zombies are logically conceivable (the concept is not logically contradictory)

Zombies are therefore logically possible

If a zombie can exist in a possible world, then mental states cannot be identical to brain states

(If A is B it cannot be possible to have A without B).

Conceivability - again

If brain states are not identical with mental states it is conceivable for someone to be in pain without having the appropriate brain activity

It is therefore metaphysically possible for someone to be in pain without having the appropriate brain activity

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in this case, there cannot be a numerical identity between brain and mind

The argument is circular

To say that it’s possible for there to be a zombie is just to say that the brain does not produce mental states i.e. and that the identity theory is false, but this is the point that the zombie argument is supposed to prove.

We may deny that zombies are logically possible on the ground that they're inconceivable. Dennett says that thinking that zombies exist is like thinking ‘you can remove health while leaving all bodily functions and powers intact’.

However, the identity theory has been put forward as a matter of empirical investigation. We could have discovered that minds are not realised in brains or that ‘pain’ is something other than firing of c fibres. So logically pain could have been non-physical. In which case zombies that are physically identical but without qualia are logically possible.

Knowledge/Mary Argument (Frank Jackson)

(P1) Prior to her release from the room, Mary had complete knowledge of all the physical facts of human colour vision

(P2) On leaving the room. Mary learned a new fact about human colour vision

(C) Therefore, not all the facts about human colour vision are physical facts

At least some mental states are not physical brain states

This begs the question. If Mary knows all the physical facts about colour vision, she will only learn something new if there are non-physical facts about it, but this is what the Physicalist denies!

Dennett says that if Mary knows all the physical facts about colour vision, she would understand how neurobiology gives rise to the experience of any colour and would recognize it when she sees it. If Mary’s captors tried to trick her, by first giving her a blue banana, instead of saying ‘that’s what yellow looks like, she would say: “Bananas are yellow, but that one's blue.”

The Acquaintance Hypothesis

Mary does gain something, but she doesn't gain any new knowledge. To have propositional knowledge of P is simply to know that PTo have acquaintance knowledge of P is to be familiar with P in the most direct way possible

Take some quale, e.g. what it’s like to see red, this is a physical property. Before release Mary knows everything about what it’s like to see red, after release, Mary becomes acquainted with what it’s like to see red. We must distinguish what is known from how it is known.

The irreducibility of consciousness

The subjective experience of pain, i.e. what it feels like, is an essential part of our concept of pain. Brain processes are (in principle at least) publicly observable, whereas pain is a private event. Any attempt to reduce this experience to purely objectively neurological processes inevitably leaves something out. If this is so, brains and minds cannot be identical.

Identity theory claims that it is possible for the same thing to appear in different ways. Through introspection my brain is a realm of conscious experience. Neurologically it is a complex physical

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organ consisting of different kinds of nerve cells. As we saw when discussing the masked man fallacy, the fact that the mind appears radically unlike the brain doesn’t show that it isn’t in fact the brain.

The irreducibility of intentionality

Intentionality is the property of certain conscious states, such as beliefs, desires, hopes and fears, that makes them represent or point to states of affairs beyond them. We cannot simply believe, or desire, or hope; we must believe, desire or hope for something. So these states of mind are necessarily about something. No purely physical system can represent, or be about something in this sense. If brain states cannot be intentional, then mental states cannot be reduced to the brain.

The interaction Problem

Mental states cannot be physical since we cannot be physically influenced by the things they are about. Similarly, a future event cannot be physically connected to a current one. We can even think about things that never have and never will exist.

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Eliminativism

Eliminativism is not strictly speaking a form of reductionism, instead it seeks to abandon or ‘eliminate’ all talk of the mental, and refer to brain processes instead. This means that there are no mental properties and that nothing exists that corresponds to mental terms like ‘belief, ‘desire’ etc.

There are different degrees of Eliminativism and it is possible to be an eliminativist about some, but not all, mental states. Partial eliminativism claims that, while most mental states (e.g. those involving belief and desire) do not exist, some 'qualitative' mental states such as pain, do exist, but can be ‘reduced’ to brain functions and explained in materialist, neuroscientific terms.

Benefits of Eliminative Materialism

There is no longer a ‘mind-body’ problem, since the theory that implies there are minds (folk-psychology) can be rejected as false and misleading. This in turn offers a solution to the 'problem of other minds’.

The thesis of the causal closure of the physical. Since every physical event has a sufficient physical cause, the real causes of my actions must be physical events such as neuronal activity in my brain. Therefore, mental events such as decisions cannot be among the causes of my actions and so a theory which describes mental events, as folk psychology does, cannot give the real explanation of my actions.

Paul and Patricia Churchland are most notably associated with Eliminativism. Paul Churchland claims that ‘mature neuroscience’ will eliminate all talk of mental states and that significant parts of our language are going to have to change as a result.

Paul Churchland challenges Folk Psychology’s theory that propositional attitudes explain and predict certain behaviour.

Propositional attitudes involve relations to propositions, and can be expressed: (“x phis that P”) where phi refers to a mental state e.g. John believes that his computer is broken; John suspects that...; John fears that...; etc.

The Infallibility Thesis: the intuitive certainty of the reality of mental states

In the Meditations Descartes concluded that he could not reasonably doubt the contents of his own mind (the infallibility thesis). This was his first ‘clear and distinct idea’. Perhaps the most obvious objection of Eliminativism is the appeal to introspection (my own experience of my interior mental life). Because I have infallible access to my own thoughts, I can verify the existence of mental states directly. This conviction is not based on a ‘theoretical’ viewpoint concerning other people’s behavior’, I am directly aware of the existence of desires, thoughts and pains, and therefore any theory that denies their existence has to be false (The Moorean Shift).

Appeals to what is obvious are problematic in the history of ideas. Descartes was certain that he was a thinking substance, but we have good reasons to challenge substance dualism. Phenomenon like reactive disassociation undermine our common-sense conception of pain and our conviction that pain is one mental state.

The 'phenomenological fallacy' is a term coined by Place to describe the ‘mistake’ of supposing that there are entities within our mind that we perceive on a ‘sort of internal cinema or television

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screen, usually referred to as the 'phenomenal field’. All we can be ‘intuitively certain’ of is the existence of the phenomena we want to explain; we cannot argue from the fact that people are sometimes in pain, to the conclusion that there is a such a thing as the pain they experience.

Churchland attacks the Infallibility Thesis. He says that it is wrong to claim that because I have immediate access to my own mental states, I cannot be mistaken about them. This is because there is a distinction between a conscious state and a description of that conscious state. The moment we try to identify our immediate experiences; we go beyond those experiences. Folk Psychology’s framework of beliefs, desires etc. is not the ‘raw data’, it is a theory which we use to describe and classify the raw data.

The Theory-theory: Folk Psychology is a theory

The theory-theory claims that Folk Psychology is a theoretical, propositional approach involving claims to ‘knowledge-that’ beliefs, desires etc. exist and are related to each other and to behaviour in law-like ways.

Churchland argues that neuroscience will provide a more accurate conceptual framework that will have no place for concepts like ‘belief, ‘desire’ or ‘intentional content’.

Eliminativism is self-refuting

Churchland’s argues that folk psychology is an empirical theory which is why we can think about proving that it is false and eliminating its concepts. If it is meaningful, Eliminativism must express genuine, verifiable beliefs. But, in this case, since it denies there are such things as beliefs, it must be false. We cannot conceive that folk psychology is false, because the very idea, presupposes the folk psychological concept of intentional content. At least until we have another, better theory of meaning, the assertion that Eliminativism is true undermines itself.

Churchland responds by pointing out that this objection presupposes the truth of folk psychology and he gives an analogous argument about vitalism to show the circularity in the reasoning. We can accept that it’s not possible to deny Folk Psychology coherently using the framework of Folk Psychology, but under a new account of humans’ internal life and behaviour (for example ‘mature neuroscience’), it may be possible to deny the existence of beliefs whilst explaining the phenomena.

The theory-dependence of observation

For Churchland the problem lies in assuming that experience shows us the nature of what we observe, with no mediation from our theoretical expectations. Making any kind of observation at all requires some conceptual framework. He gives the example of people who experience heat in the same way we do but describe it as caloric pressure derived from a fluid, that flows from hotter to colder bodies. They even claim to perceive caloric directly. The same is true for observations of our own minds. When we introspect, we describe and classify what is going on in our ‘minds’ using the theory of Folk Psychology.

Folk Psychology is not a theory - rejecting the Theory-theory

It is possible to argue that folk psychology is not a theory, but something we are constrained to do by our nature as human beings. Folk Psychology is not given in propositional form, it’s more like an intricate social practice involving abilities and skills.

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This response depends on a naive conception of what a theory is. Folk Psychology cannot be saved by insisting it's a social practice, because social practice and theory are often interrelated.

Simulation TheorySimilation theory suggests that Folk Psychology is a skill based theory that involves ‘knowledge-how’. We use empathy to simulate the mental states of others by "putting ourselves in their shoes”. We then use these mental states in our understanding of the world and our decision-making (analogous to Wittgenstein’s view of the way we use language to understand ourselves and others). Simulation theory is supported by research into Autism and actions of ‘mirror’ neurons.

The Eliminativist may accept that Folk Psychology involves running simulations, but claim that these are based on an underlying theory (Theory-theory). Daniel Dennett suggests that running a successful simulation depends on existing theoretical knowledge, (suspension bridge example) so ‘knowing-how’ often depends on ‘knowing-that’.

Theories are falsifiable

The laws of Folk Psychology aren’t a matter of conceptual truth. Folk psychology is an empirical theory and mental states are theoretical entities that we use to describe and classify immediate experience. Like all empirical theories it is falsifiable in principle and its entities are eliminable.

Our acceptance of Folk Psychology is conditional on it doing the best job of explaining the observed phenomena. If we find that it conflicts with the observed phenomena, or that we have another theory that does a better job of explaining the phenomena, we are rationally obliged to abandon it and the system of concepts it contains, such as the existence of 'beliefs’,'desires’ etc.

Using the principle of Ockham’s razor, we have no need for Folk Psychology and no reason to believe that it is true.

Reasons to think that Folk Psychology will be falsified

In ‘Eliminative materialism and the propositional attitudes’ Churchland claims that folk psychology is a theory that is likely to be false for a number of reasons:

Explanatory deficienciesThere are many aspects of mental life where folk psychology cannot provide explanations of human behaviour, such as the nature of intelligence, sleep, perception, memory and learning. The concepts used even in modern psychiatry, grounded as they are in our ordinary folk-psychological concepts, are often inadequate as an account of what goes on in mental illness.

We can object that Folk Psychology is not intended to be a theory about the beliefs, desires etc. that make up our mental life. It is only meant to account for human behaviour; or more specifically, human action. If we consider it to a theory of human behaviour even Churchland admits that folk psychology ‘does enjoy a substantial amount of explanatory and predictive success’. Ideas about unconscious beliefs and desires have become part of modern Clinical Psychology and Cognitive behaviour therapy has proved an effective way of treating obsessive behaviours and addiction.

Eliminativism could reply that these points are not very strong. The mere fact that a theory appears successful in prediction, does not show that it accurately represents the way things really are. We need to know how human action or behaviour relates to the rest of mental life. To have different sorts of theories explaining different aspects of the mind is unsatisfactory. Also, developments in

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folk psychology are relatively superficial and its explanations of behaviour are less powerful than those we find in the ‘true’ sciences.

An "anthropological" argument

Unlike other, since disproved folk theories, folk psychology has endured because it provides a whole series of widely held and interconnected ways to understand the world. Its basic concepts are found in every culture and it would appear that the adoption of this theory has contributed to our success as a species.

Stagnation

Churchland claims that Folk Psychology represents a ‘degenerating research programme’. It is not keeping pace with scientific understanding of the world and human nature. Folk Psychology hasn’t developed significantly for thousands of years and there has been little advance in solving earlier problems. This, ‘is a very long period of stagnation and infertility for any theory to display’. In the past, mental states were attributed to natural phenomena or supernatural agents. Now the domain of Folk Psychology has become increasing restricted. Successful scientific theories are able to develop and expand and neuroscientific explanations are constantly growing in scope and power.

Psychology, Sociology, Anthropology, political theory, moral theory, etc. are all dependent on Folk Psychology. Neuroscience may have shed a great deal of light on the brain, but in almost all social science it is fairly impotent.

Incompatibility with the scientific worldview

Scientific research indicates a strong connection between brain events and behaviour. Therefore, our common-sense theory of the mind needs to be related to a neuroscientific theory. Although folk psychology enables us to make some rough-and-ready predications of other people’s behaviour, it does not tell us about the real neurological causes of their actions. In particular, the central idea of ‘intentional content’ is highly problematic.

Churchland's argues that in Folk Psychology propositional attitudes are essentially linguistic and function like ‘sentences in our heads’. However, we don't find sentence-like structures in the brain and all other animals and some humans (babies and brain damaged adults) don't understand language, so don’t have propositional attitudes, but still seem to engage in intelligent cognition.

When I describe an external state of affairs (e.g. there is a squirrel in the tree) I'm not ascribing a sentence-like structure to the objects themselves. To think so would be to confuse my description of the thing with the thing itself. Similarly, when I say “Miles believes that the squirrel is in the tree", I’m not ascribing a sentence-like structure to Miles' belief. To have a belief, a desire etc. may simply have a particular attitude towards a specific representation of the world. Understood in this way, propositional attitudes can be attributed to animals and babies.

Churchland argues that cognition should be explained in terms of synaptic connections between different populations of neurons. He uses the analogy of a television, where information is encoded as patterns of activity in hundreds of thousands of pixels. For example, in the brain information is sent down the axonal fibres and results in an activation pattern in the neurons at the visual cortex. This activation pattern spreads by way of synaptic connections in the brain and might eventually direct the muscles to move.

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However, there is a problem with this argument. Consider an analogy with computers: if you were to look at the hardware of my brain, you wouldn't find anything like the computer programs I'm using. If you want to understand a computer program, you need to go to a higher level of analysis. The same can be said of the propositional attitudes, it’s no surprise that we don't find them in the neurobiological structure of the brain because that is the wrong level of analysis.

Past Folk theories

When we look at other folk theories based on ‘common sense’, we find many examples of elimination. Folk cosmologies, have been wholly discredited. It's implausible to suppose that our folk theory of the mind happened to get it right, especially since consciousness is such a complex phenomenon.

In the history of science, we often replace one theory with another, once we give up the theory of folk psychology, Churchland believes we will adopt the insights and language of neuroscience as a much better explanation of behaviour.

There are problems with Churchland's argument as many past ‘folk’ theories have been reduced rather than wholly eliminated, so the induction is fairly weak. He admits himself that although modern science suggests that Folk Psychology is ‘at best a highly superficial theory, a partial and unpenetrating gloss on a deeper and more complex reality…it does not suggest that it is a false theory"

Even supposing that we do develop an alternative, neuroscientific theory of human behaviour and mentality, this may not result in us abandoning the language and concepts of folk psychological theory. The most likely outcome is that mental concepts such as belief and desire will be revised in the light of scientific discovery, but that we will still refer to them. This view is known as revisionary materialism.

Patricia Churchland recognises that some things are more plausible candidates for reduction by neuroscience than others. Intentional content is a problem for attempts to reduce folk psychology to neuroscience. A particular molecular structure or physical process, described in physical terms, is not ‘about’ anything so it is difficult to see how intentional mental states can be brain states.

The indispensability argument for Folk Psychology

(P1) We are committed to the existence of those entities that are indispensable to our best scientific theories

(P2) The entities of Folk Psychology are indispensable to our best scientific theories;

(C) We are committed to the existence of the entities of Folk Psychology

Theories of Reference

The crucial premises in the Eliminativist's arguments are:

(1) that Folk Psychology is a theory and

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(2) that Folk Psychology will be falsified

But moving from these premises to the conclusion that the posits of Folk Psychology (beliefs, desires, etc.) don't exist, depends on holding a particular theory of reference.

Description Theory

The description theory says that the meaning of a name is given by the cluster of descriptions associated with it. If all or most of the descriptions refer to an actual object or state of affairs, then it exists. If there is no object that satisfies most of the descriptions, then it follows that the thing doesn’t exist.

Folk Psychology postulates that pain:

(1) is a mental state:

(2) that is usually caused by bodily injury:

(3) that usually causes distress and a desire to relieve the pain

(4) that, in conjunction with the desire, usually causes nursing of the damaged area... etc.

If there is no object or state that satisfies most of these descriptions, then it follows, given the description theory, that “pain” doesn’t refer to anything and so pains don’t exist.

The Causal-Historical Theory

However, the description theory is not the only option. In the causal-historical theory, suggested by Saul Kripke names refer to whatever object they're linked to in. All that the Causal-Historical theory requires is an appropriate ‘naming event’ to fix the reference, followed by an appropriate chain of ‘reference-borrowing’ as people continue to use the name.

Even if Folk Psychology is radically wrong, it doesn't follow that beliefs and desires etc. don't exist. Critics claim that Paul Churchland needs to do more than just show that Folk Psychology is wrong. The original aim was to question the ontology of mental phenomena (not the ontology of a failed theory).

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