PHILOSOPHY OF KNOWLEDGE & REALITY

Transcription

1 PHILOSOPHY OF KNOWLEDGE & REALITY W E E K 7 - D A Y 2 ( T / T H ) : E P I S T E M O L O G Y E M P I R I C I S M, R A T I O N A L I S M, M I D T E R M D I S C U S S I O N

2 REVIEW: EPISTEMOLOGY How do We Know Anything? Three Major Theories of Justification: Skepticism Empiricism Rationalism

3 REVIEW: EMPIRICISTS We Can Know Through Experience/Perception! But Our Perceptions Are not Always Trustworthy 1 Problems of Perception

4 REVIEW: EMPIRICISTS We Can Tell You - John s brain has brain cells. But They Can t Tell Us - All brain s have brain cells. 2. Problems of Induction

5 REVIEW: EMPIRICISTS We Can Tell You - Pool stick hit cue ball, cue ball hit, 8 ball, 8 ball goes into corner pocket. But They Can t Tell Us - One thing caused the other to happen. 3. Problems of Causation

6 REVIEW: RATIONALISM What do the rationalists say about these problems? WE DON T HAVE THESE PROBLEMS. REAL KNOWLEDGE ONLY COMES FROM REASON!!

7 REVIEW: RATIONALISM Using Our Intellect (reason/logic) Example #1 If know sum of angles = 180 degrees, angle C =? Example #2 If one plank is 2 in. long How long are two planks together? What s the empirical approach to this question? What s the empirical approach to this question?

8 REVIEW: RATIONALISM Necessary Truths Exist (Truth is not Contingent on Experience) A bachelor is an unmarried male. 2+1 = 3 A sister is a female sibling. Two is more than one.

9 REVIEW - RATIONALISM: USE OF DEDUCTION Use of Reason to Expand Knowledge Ex ample1: If John is a bachelor. Then John does not have a wife. Example 2: If 2 + x = 3 Then X = 1 Example 3: If Mary has a female sibling, Then Mary has a sister. Example 4: If Juan has 2 cars, and Jen has 1 car, Then Juan has more cars than Jen.

10 CRITIQUE OF RATIONALISM So is rationalism the only path to true knowledge? 1. Wait a minute. Let s look at those necessary truths again. A bachelor is an unmarried male. 2+1 = 3 A sister is a female sibling. Two is more than one. They are all truths by definition. They don t tell us anything about the world. Can that really be knowledge?

11 CRITIQUE OF RATIONALISM So is rationalism the only path to true knowledge? 2. Let s take a look at that deductions again. If John is a bachelor. Then John does not have a wife. If Mary has a female sibling, Then Mary has a sister. If Juan has 2 cars, and Jen has 1 car, Then Juan has more cars than Jen. To know anything about the world, you needed to have used empiricism before you use deduction.

12 DISCUSSION Describe three issues (perception, induction, causation) with empiricism. How might you defend it against its critics? Why do some find rationalism more appealing than empiricism as a justification for knowledge? Do we ever really know anything a priori? If so provide examples. If not explain why.

13 KANT S EPISTEMOLOGY Immanuel Kant ( ) German Philosopher Changed epistemology forever with 1) Kant s Compromise 2) Kant s Copernican Revolution

14 KANT S COMPROMISE Yes, empiricists, there are contingent truths known by experience. But the mind does not passively take in sensory information. We are not blank slates. Yes, rationalists, there are necessary truths known through reason. But knowledge is not gained by reason alone. Let s make a compromise!!

15 KANT S COMPROMISE We need to change the way we look at knowledge and say there are different types of truths. Distinction #1: a priori (before experience) a posteriori (after experience) Distinction #2: Let s make another distinction: Analytic = true by definition, not new info. Synthetic = truth beyond definition alone, provides new info

16 KANT S COMPROMISE 4 CLASSIFICATIONS OF JUDGMENTS See! Reason does give us knowledge! Synthetic a priori knowledge The shortest distance between two points is a straight line. The velocity of a body remains unchanged unless acted on by an outside force. Every event has a cause a posteriori knowledge John is under 12 ft tall. Mount Everest is the highest mountain on Earth There are more people in San Francisco than Milpitas. Analytic All bachelors are unmarried. All triangles have three angles. A red ball has color. This comes from experience. Where does this come from? This comes from definition.

17 KANT S REVOLUTIONARY IDEA The mind does not passively conform to its objects. On the contrary, the objects of consciousness conform to the inherent, a priori structures & categories of the mind itself. Two big ways the mind structures & categorizes reality: Time and Space

18 KANT S REVOLUTIONARY IDEA What does this mean? Rationalist and Empiricist Knowledge Isn t Noumena You Can t Know Anything About How Reality Actually Is! Not about evil demons or dreams, but about how your mind works.

19 KANT S COPERNICAN REVOLUTION 1. IMPACT ON RATIONAL TRUTHS OF THE WORLD (SYNTHETIC A PRIORI) Example #1: Every event has a cause (or even simply causation exists ). Our mind understands objects as existing in time. This truth is true because of how the mind structures reality as existing sequentially, in the flow of time.

20 KANT S COPERNICAN REVOLUTION 1. IMPACT ON RATIONAL TRUTHS OF THE WORLD (SYNTHETIC A PRIORI) Example #2 The shortest distance between two points is a straight line. Our mind understands objects as existing in space. This truth is true because of how the mind structures reality as existing WITHIN space. (you actually can t see straightness)

21 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS) All sense experience is then filtered and shaped by our minds. 1 2

22 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS) D Which segment is longest: AB, AD, DB, DC, BC?

23 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

24 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

25 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

26 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

27 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

28 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

29 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

30 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

31 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON EMPIRICAL TRUTHS (SYNTHETIC A POSTERIORI TRUTHS)

32 KANT S COPERNICAN REVOLUTION All rational understanding and perception of reality is filtered and shaped by our biology and mind. Therefore: Our truths are never about reality. Our truths are about how our mind best makes sense of reality. Therefore: We never know reality as it is (Noumena). We can only know it as shaped by our mind (Phenomena).

33 NEW THEORY OF THE UNIVERSE

34 NEW THEORY OF THE UNIVERSE Leonard Susskind Raphael Bousso What?!!!

35 NEW THEORY OF THE UNIVERSE Holographic Universe?