Philosophy E156: Philosophy of Mind Week One: Plato’s Problem.

Philosophy E156: Philosophy of Mind

Week One:Plato’s Problem

“The Chomskyan Revolution”

• Starting with a discussion of what is something called “the Chomskyan revolution”

• Called this because of Noam Chomsky, professor emeritus of linguistics at M.I.T.

• The term usually meant only to refer to Chomsky’s field, linguistics

• But my view is that the term can also be used more broadly to refer to a shift in our thinking about the human sciences in general and about the mind in particular

• Given that our subject is the philosophy of mind, this shift in thinking should interest us

Empiricism

• One way to characterize the shift in thought that I have in mind is to contrast it with what came before it

• For several hundred years, the approach to thinking about the mind that was dominant in the English-speaking world is one that is today usually referred to as “empiricism”

• A number of rather different doctrines and research strategies are collected under the rubric of “empiricism,” but common to them is usually a view that can be stated in roughly this way:

– All our ideas and all our knowledge are rooted in experience

John Locke’s Empiricism

• Empiricism: ideas rooted in experience – – “Let us then suppose the mind to be, as we say, white paper, void of

all characters, without any ideas: How comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? Whence has it all the materials of reason and knowledge? To this I answer, in one word, from EXPERIENCE. In that all our knowledge is founded; and from that it ultimately derives itself. Our observation employed either, about external sensible objects, or about the internal operations of our minds perceived and reflected on by ourselves, is that which supplies our understandings with all the materials of thinking. These two are the fountains of knowledge, from whence all the ideas we have, or can naturally have, do spring.” (Essay, Book II, Chapter One, sec. 2)

Where We Get Ideas

• Locke thought we got simple ideas from sensations and complex ideas from simple ideas, by one of three methods. – Ideas come from sensations – idea of red from red

sensations– Abstraction of ideas – not a concern here – Comparison of ideas – seeing the relationship between

two ideas. – Compounding of ideas – addition

• Idea of a horn plus idea of a horse gives idea of unicorn.

Locke Against Innateness

• One of Locke’s arguments against innateness:– “… if a child were kept in a place where he never

saw any other but black and white till he were a man, he would have no more ideas of scarlet or green, than he that from his childhood never tasted an oyster, or a pine-apple, has of those particular relishes.” (Essay II i 6)

Hume’s Empiricist Account of Knowledge

• Hume’s account of knowledge (Enquiry, Section IV):– “If we would satisfy ourselves, therefore, concerning the

nature of that evidence, which assures us of matters of fact, we must enquire how we arrive at the knowledge of cause and effect.

– “ … [T]he knowledge of this relation is not, in any instance, attained by reasonings a priori; but arises entirely from experience, when we find that any particular objects are constantly conjoined with each other. Let an object be presented to a man of ever so strong natural reason and abilities; if that object be entirely new to him, he will not be able, by the most accurate examination of its sensible qualities, to discover any of its causes or effects.”

Hume’s Adam Example

• Hume’s famous thought experiment involving Adam:– “Adam, though his rational faculties be supposed, at

the very first, entirely perfect, could not have inferred from the fluidity and transparency of water that it would suffocate him, or from the light and warmth of fire that it would consume him. No object ever discovers, by the qualities which appear to the senses, either the causes which produced it, or the effects which will arise from it; nor can our reason, unassisted by experience, ever draw any inference concerning real existence and matter of fact.”

A Different Approach: Rationalism

• A very different approach is associated with Plato, Descartes and Leibniz

• This approach is usually labeled “rationalism”:– Not all our ideas and not all our knowledge

are rooted in experience

Chomsky’s Rationalism

• Empiricism dominated throughout the 18th and the 19th centuries, well into the 20th

• In the 20th century, empiricism speculation took the even more extreme form of behaviorism

• A major aspect of the Chomskyan revolution has consisted of rejecting much of the empiricism thinking and reviving rationalism

Agenda

• I want to look at a historical precedent that Chomsky cites in defense of rationalism – Plato’s dialogue Meno

• Then I want to turn to some contemporary parallels between Plato’s argument there and arguments from linguistics

“Plato’s Problem” and the “Poverty of the Stimulus” Argument

• The term “Plato’s Problem” and the term “argument from poverty of the stimulus” – the term that has come to be most closely associated with Chomsky’s proposed solution to Plato’s Problem – both come from Chomsky’s 1980 book Rules and Representations

• In that book, Chomsky associates Plato’s Problem with the question of “how we can know what in fact we know” – or in Russell’s special formulation,– “[H]ow comes it that human beings, whose contacts with the world

are brief and personal and limited, are nevertheless able to know as much as they do know?”

Bertrand Russell, Human Knowledge: Its Scope and Limits (1948)– Chomsky discusses Russell and his view about this at length in

Problems of Knowledge and Freedom (1971)

The “Argument from Poverty of the Stimulus”

• The second term – “argument from poverty of the stimulus” – Chomsky does not explicitly define, but does link it to “the vast qualitative difference between the impoverished and unstructured environment … and the highly specific and intrinsic characters that uniformly develop” in human beings

What’s Platonic about Plato’s Problem?

• Now I would like to take seriously Chomsky’s characterization of the problem as “Plato’s Problem” and ask what it is, exactly, that is supposed to make it Plato’s problem

• In answering this question, one is helped by the fact that Chomsky discusses what he calls Plato’s Problem at several places in connection with Plato’s dialogue Meno

• Meno is discussed in most detail in Language and Problems of Knowledge (1988)

Plato’s Problem and Meno’s Paradox

• Chomsky’s discussion of Meno has to do almost entirely with the part of Plato’s dialogue involving the encounter between two characters in the dialogue: the philosopher Socrates and Meno’s slave boy

• Chomsky notes, correctly, that what is known as Plato’s “theory of recollection” is motivated by what happens during the encounter

• Chomsky does not discuss Meno’s Paradox, which motivates much of the discussion in Plato’s dialogue, but it might be helpful to begin with it and to recall what it is and why, in the context of the dialogue, Socrates appeals to the theory of recollection at all

Meno’s “What is X?” Question: the Nature of Virtue

• The dialogue Meno is a fictional encounter between the philosopher Socrates, who had until his death been Plato’s philosophical mentor, and the orator Meno

• Meno: “Can virtue be taught?”• Socrates: I cannot answer until I know what virtue is• Meno offers examples of virtue and several definitions• Socrates rejects the examples and refutes the definitions• Meno gives up, comparing Socrates to a “torpedo fish,”

numbing its prey

Meno’s Skeptical Argument: Meno’s Paradox

Socrates’ Restatement of Meno’s Argument

A Formalization of Meno’s Skeptical Argument

(1) A person cannot search for what he or she knows (since there is no need to search for something already known).(2) A person cannot search for what he or she doesn’t know (since he or she doesn’t know what to look for and couldn’t recognize it if he or she were to encounter it). __ . ∴ A person cannot search for anything.

Socrates’ Response

Meno: Does that argument not seem sound to you, Socrates? (81A)Socrates: Not to me.… I have heard wise men and women talk about divine matters….Meno: What did they say?Socrates: What was, I thought, both true and beautiful.Meno: What was it, and who were they?...

Socrates’ Response (cont.)

Socrates’ Response (cont.)

Does Socrates Accept Meno’s Argument?

• Supporting “Yes,” he summarizes what Pindar and other poets say, calling it “true and beautiful”: “As the soul is immortal, has been born often, and has seen all things here and in the underworld, there is nothing which it has not learned….”

• Supporting “No,” he says “Not to me” when Meno asks him if the argument seems sound, and later asserts, “We must … not believe that debate’s argument.”

How long is the side of a square twice the size of a given square?

The Geometry Lesson

The Geometry Lesson (cont.)

The Geometry Lesson (cont.)

Socrates’ Argument

• After finishing his dialogue with the slave boy, Socrates asserts to Meno (at 85b-e) that – (1) the boy throughout stated what he believed (85b)– (2) Socrates only asked him questions and never taught

him (85d)– (3) the boy had never been taught geometry (85e)

• From (1), (2) and (3), and the fact that the boy arrived at the correct answer, Socrates infers (at 85d) that the boy recollected the answer.

A Digression:Chomsky on Teaching

• Chomsky: I don’t have any theory of rhetoric, but what I have in the back of my mind is that one should not try to persuade…. But to the extent that I can monitor my own rhetorical activities, which is probably not a lot, I try to refrain from efforts to bring people to reach my conclusions.

• Q. Is that because you might lose credibility or lose the audience?

• A. Not at all. In fact, you’d probably lose the audience by not doing it. It’s just kind of an authoritarian practice one should keep away from. The same is true for teaching….

Chomsky on Teaching (cont.)• “ … It seems to me that the best teacher would be the one who allows

students to find their way through complex material as you lay out the terrain. Of course, you can’t avoid guiding because you’re doing it a particular way and not some other way. But it seems to me that a cautionary flag should go up if you’re doing it too much because the purpose is to enable students to be able to figure out things for themselves, not to know this thing or to understand that thing but to understand the next thing that’s going to come along; that means you’ve got to develop the skills to be able to critically analyze and inquire and be creative. This doesn’t come from persuasion or forcing things on people. There’s sort of a classical version of this—that teaching is not a matter of pouring water into a vessel but of helping a flower to grow in its own way—and I think that’s right. It seems to me that that’s the model we ought to approach as best possible. So I think the best rhetoric is the least rhetoric.”

– “Language, Politics, and Composition,” Journal of Advanced Composition 11 (1991).

How Could the Boy Do It?

• In Language and Problems of Knowledge, Chomsky calls this “the first recorded psychological experiment (at least, ‘thought experiment’).”

• He summarizes the problem that Plato raises this way: “The experiment raises a problem that is still with us: How was the slave boy able to find the truths of geometry without instruction or information?”

Three Challenges to Socrates’ Argument

• Critics challenge (1), (2) and the inference to recollection – – (1) that the boy only stated what he believed

Some critics say that the boy parroted Socrates– (2) that Socrates only asked him questions and

never taught him Some critics say that Socrates guided him by asking leading questions and diagramming the answer

– The inference from (1), (2) and (3) to the conclusion that the boy recollected the answer

Critics say that the boy simply “figured it out”

Recall the Formalization of Meno’s Puzzle

(1) A person cannot search for what he or she knows (since there is no need to search for something already known).(2) A person cannot search for what he or she doesn’t know (since he or she doesn’t know what to look for and couldn’t recognize it if he or she were to encounter it). __ . ∴ A person cannot search for anything.

One Reason Socrates Rejects Meno’s Argument

Regarding (1) – the premise that a person cannot search for what he or she knows – Socrates would agree that a person cannot search for what he or she knows consciously but would argue that a person can search for what he or she knows unconsciously. Searching and finding what we already know but only unconsciously is according to Socrates what we call “recollection.”

A Related Reason Socrates Rejects Meno’s Argument

Regarding (2) – the premise that a person cannot search for what he or she doesn’t know – Socrates would agree that a person cannot search for what he or she doesn’t know even unconsciously but would argue that a person can search for what he or she doesn’t know consciously. Searching and finding what we don’t know consciously and bringing it to consciousness, again, is according to Socrates what we call “recollection.”

Unconscious Knowledge

• We are familiar with such cases of unconscious knowledge from ordinary life

• I know the name of my daughter’s friend but I cannot currently bring it to mind

• So I search for it – in this case, search my memory for it

• The fact that I can come reliably to report it without being told what my daughter’s friend’s name is is taken as evidence that I knew it, just unconsciously

Overkill, However

• Ultimately, Socrates also concludes not just that the slave boy recollected the geometric principle but that – (1) the recollection is explained by innateness, and – (2) the innateness is explained by reincarnation (and

apparently, by the soul’s knowledge by way of a perception-like acquaintance with the Platonic forms)

• Notice that there is extreme overkill here –• Even if we accept the recollection inference, the

further inferences to innateness and reincarnation are entirely unnecessary for Socrates’ announced purpose – to refute Meno’s paradoxical argument

Chomsky on Leibniz

• Descartes endorses Socrates’ argument, perhaps after separating the “reminiscence” part (see the 1643 letter to Voetius)

• Chomsky cites not Descartes’ response but Leibniz’s:

“Centuries later, Leibniz argued that Plato’s answer was essentially correct but that it must be ‘purged of the error of preexistence.’” (Language and Problems of Knowledge, p. 4.)

Phaedo

• The later dialogue Phaedo gives a different perspective on the recollection argument, citing the relevance of diagrams:– But tell me, Cebes, said Simmias, interposing, what proofs are given of

this doctrine of recollection? I am not very sure at this moment that I remember them.

One excellent proof, said Cebes, is afforded by questions. If you put a question to a person in a right way, he will give a true answer of himself; but how could he do this unless there were knowledge and right reason already in him? And this is most clearly shown when he is taken to a diagram or to anything of that sort.

What Is It About Diagrams?• The idea seems to be that the boy brings something to

the encounter with Socrates, without which the discussion could not get off the ground

• It is the ability to see the imperfect lines in the sand as perfect

• The boy already knows what rectangles and triangles are, and the lines in the sand simply prompt him to recollect what he knows

• It’s not that he knows the theorem he arrives at – but that he at least knows properties of geometric figures in some fashion

What Descartes Cites• It’s this conception of geometric knowledge that Descartes

seems to have in mind in a passage from Replies to Objections V that Chomsky cites in his 1966 book Cartesian Linguistics (on p. 104):– Thus, when as children we first saw a triangular figure drawn on paper,

that can’t have been what showed us how the true triangle studied by geometers should be conceived, because the pencilled figure contains the true triangle only in the way that a rough unpolished carving contains the finished statue of Mercury that it is going to become. Our seeing the pencilled triangle did give us the thought of a true triangle, but not in the way you think. What really happened was this: We already had the idea of the true triangle, which was easier for our mind to grasp than the more complex pencilled triangle; so when we saw the complex composite figure, what we took in was not the figure we saw but rather the true triangle.

Skepticism, but a Linguistic Parallel

• I believe that some skepticism about the relevance of Plato’s argument to Chomsky’s view is warranted

• I will suggest some reasons to be skeptical later

• Now I want to look at a linguistic parallel to Socrates’ geometry argument

My own example of a Poverty of the Stimulus Argument

Grammatical Rule (A)

(1) I will have a cold if I don’t dress warmly

(2) Will I have a cold if I don’t dress warmly

Grammatical Rule (A): If a sentence like (1) is grammatical, then the corresponding sentence like (2) is grammatical.

Grammatical Rule (B)

(3) I will have a cold if I don’t dress warmly

(4) I’ll have a cold if I don’t dress warmly

Grammatical Rule (B): If a sentence like (1) is grammatical, then the corresponding sentence like (2) is grammatical.

Is The Sentence Below Grammatical?

(5) Will I’ve a cold if I don’t dress warmly

First, do you think that (5) is grammatical?Second, do you think that others in the room will say that (5) is grammatical?

Two-Part Hypothesis

• First, that everybody in the room thought that the sentence was ungrammatical.

• Second, that everybody in the room thought that everybody else in the room would judge the sentence to be ungrammatical.

POS Argument: No Evidence, Positive or Negative

• Sentences just like (5) are never produced by the child

• Thus, there could not be “negative evidence” for the child about the ungrammaticality of sentences like (5)

• Nor do adult speakers ever produce sentences just like (5) on their own or comment on them

• But there is some evidence from sentences somewhat like (5) – and it is that sentences like (5) are grammatical, because of rules (A) & (B)