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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. Copyright © 2011 Pearson Education, Inc. All rights reserved.

Epistemological Questions Do we really know objective reality? How do we know objective reality? “Objective reality” = what is independent of what we think/feel… Copyright © 2011 Pearson Education, Inc. All rights reserved.

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) Copyright © 2011 Pearson Education, Inc. All rights reserved.

LOCKE VS. LEIBNIZ ON INNATE IDEAS The Empiricist: LOCKE: NO 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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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.” Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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. Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

Empiricist Epistemology Human knowledge falls into two kinds for Hume Relations of Ideas– all rational a priori knowledge Matters of Fact– all empirical a posterori knowledge Copyright © 2011 Pearson Education, Inc. All rights reserved.

Relations of Ideas & Matters of Fact 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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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” Copyright © 2011 Pearson Education, Inc. All rights reserved.

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. BUT we NEVER “see” CAUSATION, just the association of two things! Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 This is repeated Soon when we see A happen we come to expect that B will happen right after Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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’ Copyright © 2011 Pearson Education, Inc. All rights reserved.

KANT’S “COPERNICAN REVOLUTION”: OVERCOMING SKEPTICISM BY UNITING EMPIRICISM AND RATIONALISM “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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

Copyright © 2011 Pearson Education, Inc. All rights reserved.

Copyright © 2011 Pearson Education, Inc. All rights reserved.

Copyright © 2011 Pearson Education, Inc. All rights reserved.

Copyright © 2011 Pearson Education, Inc. All rights reserved.

Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

How does this analogy help? In this analogy, raw sense data is like the bag of mixed coins. In itself, raw sense data is meaningless jumble. The coin sorter is analogous to the mind’s categories. The coin sorter provides organisation and structure and, thereby, value to the bag of coins. The mind’s categories provide organisation and structure and, thereby, meaning, to jumbled up, raw sense data. Write your own analogy…try the rules of chess and chess pieces, glasses for a short-sighted person, containers for things contained…

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

Phenomena v. Noumena II Wasup? Hi Noumena Sensibility Understanding Copyright © 2011 Pearson Education, Inc. All rights reserved.

Phenomena v. Noumena III Hi Wasup? Hi Wasup? Me You Copyright © 2011 Pearson Education, Inc. All rights reserved.

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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

A descriptive analogy to help: The Coin Sorting Machine Take a large bag of mixed coins of different types. Is there £200 there, or £25? While they remain mixed up in the bag, the coins really have no value. You cannot buy something with a bag of coins without knowing its value. Before you can spend the coins, you have to sort them with a coin sorter so that you know how much they are worth. The coins don’t really have any true value until they are sorted by the coin sorter.

Kant’s Philosophy of Mind 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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

Unity, plurality, totality Quality Reality, negation, limitation Kant’s Categories There are four main categories, each divided into three sub-categories. (HANDY TO KNOW THESE BY HEART…) Quantity Unity, plurality, totality Quality Reality, negation, limitation Relation Substance and accident, cause and effect, reciprocity Modality Possibility, existence, necessity

Kant’s Philosophy of Mind 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 Copyright © 2011 Pearson Education, Inc. All rights reserved.

KANT ON THE SYNTETIC A PRIORI AND THE PHENOMENAL AND NOUMENAL WORLDS THE SYNTHETIC A PRIORI THE PHENOMENAL AND NOUMENAL WORLDS 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 phenomenal reality is the world as we constitute it and experience it noumenal reality is the world beyond our perceptions, reality “in-itself” Copyright © 2011 Pearson Education, Inc. All rights reserved.

What is your epistemology? Where does Scientific knowledge (e.g., “Normally water freezes below 0° C”) come from? From experience (empiricism like Locke) From reasoning (rationalism) We do not have such knowledge (Hume) We construct such knowledge in our mind with data from experience (Kant) ??? Copyright © 2011 Pearson Education, Inc. All rights reserved.