philo

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Metaphysics and Epistemology

Reality: What is real?

Knowledge: What is truth?

The usual (circular) assumption:

reality is what we know as objective existence in the world;

knowledge is what we know about reality.


Epistemological Questions

Do we really know objective reality?

How do we know objective reality?

“Objective reality” = what is independent of what we think/feel…


Sources of Knowledge

Where does knowledge come from? (experience or reasoning?)

Empiricism: All knowledge comes from experience (a posteriori).

Rationalism: All reliable knowledge (scientific laws, etc.) comes from rational deliberation (innate ideas + reasoning). (a priori)


LOCKE VS. LEIBNIZ ON INNATE IDEAS

The Empiricist:

LOCKE: AGAINST INNATE IDEAS The argument from universal

consent for innate ideas is inconclusive

Children and “idiots” do not have innate ideas; we are born with a mind as a blank tablet (tabula rasa)

It is impossible to have ideas of which we are not conscious

The Rationalist:

LEIBNIZ’S REPLY TO LOCKE Sense experience alone

cannot validate general principles or laws

There is extensive evidence that we have innate cognitive structures


Rene Descartes’ Rationalism (Chapter 5, pp. 215-227)

Experience is not reliable:

The wax argument (is it the same thing after it melts?)

The dream argument

Only reason is reliable:

“I think, therefore I am.”


The Empiricist: LOCKE’S CAUSAL THEORY OF PERCEPTION: ELEMENTS OF THE KNOWING PROCESS

The entity or object in the world

Sensations (sense data, images, sensory impressions) emitted by the objects via “impulses” and transmitted to our five senses

Ideas, which Locke characterizes as “the immediate objects of perception, thought, or understanding”—in other words, the images or impressions produced in our minds by the impulses emitted by the objects

The human subject, knower, or conscious mind who is able to perceive the ideas in his or her mind and “reflect” on them, thus constructing knowledge


OBJECTS HAVE PRIMARY AND SECONDARY QUALITIES (p.253)

Primary qualities “resemble” (or “reside in”) an object even when we are not perceiving the object Solidity Extension Figure (shape) Motion or rest Number

Secondary qualities do not “resemble” (or “reside in”) an object, but are “powers” of objects to produce sensations in our minds Colors Sounds Tastes Odors


Locke’s “Substance”

What holds these primary and secondary qualities together to make them the same entity?

Locke: “Substance” (something that lies beneath these observable qualities).

But do we perceive any “substance”?---empiricism finds its own difficulty.


Empiricist turning into Idealist: GEORGE BERKELEY: “TO BE IS TO BE PERCEIVED”

There is no such thing as material substance; all that exist are “minds” and “ideas”

There is no distinction between “primary” and “secondary” qualities

What we mistakenly believe to be “material objects” are really collections of ideas in the mind of God


The Fate of Empiricism

With the success of Newtonian physics and Locke’s account of an empiricist metaphysics and epistemology Empiricism seemed to clearly have the upper

hand against rationalism David Hume (1711-1776) comes along and

shows that there is something deeply troubling about empiricism It leads to a radical kind of skepticism


Hume’s Version of Empiricism

Contents of the mind can be divided into two categories Impressions-- the actual experiences that we

have Tasting an apple, seeing a sunset, feeling pain,

or angry or jealous, hungry or sad, etc Ideas– Copies of impressions My memory of the taste of the apple, my idea of

anger, jealousy, hunger, red


Hume on Perception

Impressions and ideas are each a kind of perception for Hume they are distinguished by their ‘force and

vivacity’ Impressions are ‘our more lively perceptions’ Ideas (or thoughts) are dull and lifeless copies of

the original impression This means that both are merely mental

phenomena


The Empiricist Theory of Meaning

Words in language stand for ideas Hume endorses Locke’s distinction between

simple and complex ideas Complex ideas are composed of simple ones

Simples ones either can be traced back to an impression from which they were copied

Or else they are meaningless nonsense If an idea cannot be traced back to an

impression it is meaningless and should not be used


Empiricist Epistemology

Human knowledge falls into two kinds for Hume Relations of Ideas– all a priori knowledge Matters of Fact– all empirical knowledge

To decide which is which you apply the following rule If the negation of a true proposition in question

is a contradiction then it is a Relation of Ideas If not, a Matter of Fact (see examples next page-

>)


Relations of Ideas & Matters of Fact

Relations of Ideas All bachelors are

unmarried All triangles have three

sides A2+B2=C2 (3 x 5)=(1/2 x 30) For any sentence S,

either S is true or S is false

S can’t be true and also not true at the same time

Matters of Fact All bachelors are

messy All dogs have four legs Apples are red Rent in NYC is

expensive Subway fare is $2.00 Fire causes pain Objects when dropped

will fall The future will

resemble the past


Relations of Ideas

Relations of ideas consists of two parts Ideas And the relations between them E.g. my ideas BACHELOR and UNMARRIED MALE

are related in such a way as to make it impossible for there to be a married bachelor

This is true for all relations of ideas Their truth is independent of experience in the

sense that one does not need to go and check to see if they are true

Mathematics and logic are purely formal systems of inter-related definitions

Numbers do not need to exist to make it true that 2+2-4


Matters of Fact

Matters of Fact on the other hand have their truth determined by the way that the world happens to be (“contingent”)


Hume’s Skepticism of External World We can only experience our experience.

We do not know what is beyond our experience (“external world”).

“Mind” “Experience” “External World”


Hume’s Skepticism of Causality

Hume argues that the idea of cause and effect is a Matter of Fact because it fails to meet the two criteria of something that is a priori (relations of ideas) To deny it is not a contradiction (“water

extinguishes fire”) We cannot, without experience, predict

what the effect of any given cause will be


Hume on Cause & Effect

The idea of causation is the idea of a necessary connection between events BUT: To say that the connection is necessary is to

say that the same effect will always follow from the same cause

We do not get the idea of necessary connection from reason

And we do not get it from experience We never see the necessary connection


Hume on Cause & Effect

We have no rational reason to expect any given cause and effect relation to hold in the future

All of our inductive knowledge is founded on our belief that the future will resemble the past

But this belief is completely irrational (we have no rational basis to believe it)


Cause and Effect

All of our ideas must come from one of these two sources (matters of fact; relations of ideas)

One of the most important ideas we have is the idea of causation The idea of a necessary connection between

events Same cause = same effect EVERY TIME

All of science is based on this idea All of our common sense knowledge about the

world is based on this idea


It’s just a Habit!

So where does the idea come from? It comes from ‘a habit of expectation’

We see A happen We see B happen right after We see A happen We see B happen right after This is repeated Soon when we see A happen we come to expect

that B will happen right after


Spreading the Mind

It is the subjective feeling of expectation that we mistakenly ‘project’ out onto the events that we observe

For Hume, “we cannot know if there is anything more to the word than this” This is an epistemological claim: we can’t know if

there is a necessary connection between events NOT a metaphysical claim: There is no necessary

connection between events (we do not know)


Hume’s Challenge to Induction

Induction: The process of deriving general principles from particular facts or instances.

All inductive knowledge is based on the fallacy of assuming that the future will resemble the past But just that something has happened for a long

time is no guarantee that it will always happen So, the sun may have risen everyday so far, but

who can say with certainty that it will rise tomorrow?

Just like problem of black swans


Pavlov & Classical Conditioning

We have been trained by nature to expect certain events upon seeing certain other events Just like Pavlov’s dog

You ring the bell and bring some food The dog salivates Repeat Soon the dog salivates when hearing the bell

whether or not food comes The dog has come to expect ‘bell then food’


Classical Conditioning II

Now if the dog were to reason to itself as follows, Every time the bell has rang food has appeared This has happened everyday of my existence,

every since I was a puppy I can infer from this that the next time the bell

rings, food will appear We could easily see that the dog has made a

mistake (like Bertrand Russell’s turkey on Thanksgiving day)


Classical Conditioning III

There is no necessary connection between bell ringing and food appearing in nature How can we tell that this is not the way nature is

in reality? Nature is regular (so was the bell ringing/food

bringing relationship) Things so far have happened regularly and

predictably But we have no reason to believe that it must

continue (from an empiricist point of view)


READING CRITICALLY: ANALYZING HUME’S CASE FOR SKEPTICISM

Would you agree with Hume’s critique of knowledge claims about the external world, cause and effect, and induction? Why or why not?


KANT’S “COPERNICAN REVOLUTION”

“Hitherto it has been assumed that all our knowledge must conform to objects. But all attempts to extend our knowledge of objects by establishing something in regard to them by means of concepts have, on this assumption, ended in failure. We must, therefore, make trial whether we may have more success if we suppose that objects must conform to our knowledge.” –Critique of Pure Reason





Kant’s Dogmatic Slumber

Kant is disturbed from thinking that everything in science is fine by Hume’s argument Empiricism cannot deliver necessary truths ‘experience can teach us that something is the

case but it cannot teach us that it must be the case’

Yet science claims to discover necessary truths about nature (Scientific necessity) Even worse, Hume claimed to have shown that

human beings are essentially irrational


Transcendental Idealism

Kant agrees with Hume that we cannot learn that the causal relation is necessary and universal from experience But Hume has not shown that we can’t have a

priori knowledge For Hume something was a priori if we could

not deny it without contradiction For Kant something is a priori if is knowable

completely independently of experience


The Structure of Experience

How could our experience be the way that it is?

How is it? Objects are located in space and time Can you imagine an object which was not at any

place? No !

This is something that we can know a priori It is not dependent on experience


Conditions of all Possible Experience

It is the pre-condition for any experience at all Just like space in the room is a precondition of

having objects in the room So too space is a necessary condition of any

possible experience Thus we can know with absolute certainty that

whatever experiences we do have will all take place at some time and at some particular place


The A Priori

So Kant concludes that there is pure a priori knowledge ‘pure’ because it does not depend on experience But is rather the pre-conditions for any possible

experience It is necessary

It is not possible to have experience without space

And universal All experiences will be in space


Analytic vs. Synthetic (p. 287)

An analytic truth is one that is true by virtue of the meaning of the words themselves “All bachelors are unmarried males”---They do not add anything new to our knowledge

Synthetic truths are true in virtue of the kind of experience we have “All bachelors are messy”---They do add to our knowledge


Kant’s 4 DistinctionsA Priori

A Posteriori

Analytic

Synthetic

“All Bachelors are unmarried

males”

“All triangles have three

sides”

“Dogs bark”

“Apples taste good”

???????

Cause & effect

!!!!!!


Synthetic A Priori Knowledge

So Kant’s answer to Hume is his theory of synthetic a priori knowledge Take ‘fire causes pain’ It is synthetic, it adds to our experience But it is also a priori, that is, necessary and

universal It is a priori in the sense that we can tell by

looking at the structure of our experience that it must be a certain way


Phenomena vs. Noumena

The phenomenal world is the world as it appears to us. It is the world that we see, touch, taste, etc.

The noumenal world is the way that the world is in-itself The world as it is by itself

All we can know is the way our experience of the world will be We can’t know the noumenal world


Phenomena v. Noumena II

NoumenaUnderstanding

Sensibility

HiWasup?


Phenomena v. Noumena III

HiWasup

?

HiWasup

?

MeYou


Kant’s Philosophy of Mind

Our minds are the same (i.e., we share the same phenomenal world)

The mind has two components Sensibility Understanding

“Sensibility” takes in ‘raw’ unorganized noumena and organizes it into phenomena (our experience) Each has their categories that they use in order

to construct our experience The sensibility has Space and Time



The “understanding” has 12 categories Unity, plurality, totality, reality, negation,

limitation, substance/property, cause & effect, community, possibility/impossibility, existence/non-existence, and necessary/contingent

With these categories, and the two from the sensibility, our mind constructs our experience We can know with absolute certainty that our

experience will conform to the categories



That is the only way that experience like ours is possible The same cause must bring about the same

effect Because our mind constructs the world that way.

Yet this comes at a heavy cost Science studies our experience of the world It does not, cannot, study the noumenal world



Kant called this a Copernican Revolution in philosophy Instead of the mind passively acting like a

recorder of an outside reality Kant sees the human mind as actively

constructing reality This is his mix of Rationalism and Empiricism

Empiricism– science is synthetic knowledge Rationalism– but based on a priori categories


KANT ON THE SYNTETIC A PRIORI AND THE PHENOMENAL AND NOUMENAL WORLDS

THE SYNTHETIC A PRIORI Necessary and universally true

a priori—can be discovered independently of experience

Synthetic in the sense that it provides us with genuine information regarding our experience in the world

THE PHENOMENAL AND NOUMENAL WORLDS

phenomenal reality is the world as we constitute it and experience it

noumenal reality is the world beyond our perceptions, reality “in-itself”


What is your epistemology?

Where does Scientific knowledge (e.g., “Normally water freezes below 0° C”) come from?

1. From experience (empiricism like Locke)

2. From reasoning (rationalism)

3. We do not have such knowledge (Hume)

4. We construct such knowledge in our mind with data from experience (Kant)

5. ???

philo

Spiritual

pearson education

ideas hume

collections of ideas

innate ideasthe empiricist

primary qualities

objective reality

empiricist metaphysics

world knowledge