PHILOSOPHY OF KNOWLEDGE & REALITY W E E K 7 : E P I S T E M O L O G Y - K A N T

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1 PHILOSOPHY OF KNOWLEDGE & REALITY W E E K 7 : E P I S T E M O L O G Y - K A N T

2 AGENDA 1. Review of Epistemology 2. Kant Kant s Compromise Kant s Copernican Revolution 3. The Nature of Truth

3 REVIEW: THREE KINDS OF KNOWLEDGE 1. Knowledge by acquaintance (knowing someone/thing, familiarity) 2. Knowing how (competence, skill) 3. Propositional knowledge (know that) In philosophy, we are almost always concerned with #3 So epistemology is.

4 REVIEW: THE MAJOR THEORIES OF KNOWLEDGE Knowledge is true, justified belief. So, how can we justify our belief as being true? 1. Skepticism You can t. Problem with this theory? Global skepticism is not very practical (law, science, morality, etc..) 2. Rationalism Through reason and logic Problem with theory? Many truths are simply true by definition and do not say anything about the world. Truth that does say something often relies on empirical evidence. 3. Empiricism Through your sense experiences. Problem with this theory? 1) Senses can be deceiving and perception is subjective, 2) no causation, 3) in general knowledge

5 QUICK REVIEW: EPISTEMOLOGY Rationalist ( ) Empiricist ( ) Senses can t be trusted. Mind is a blank slate. Knowledge comes from reason (e.g. mathematics, I think, therefore I am.) Descartes Solving the perc. problem: Two qualitiesprimary & secondary. Our perceptions represent reality. Locke Empiricist ( ) Only experience ideas, so only ideas exist no material world. Mind important: To exist is to be perceived. Berkeley Empiricist ( ) Can never have general knowledge. Can never experience causes. Hume

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

7 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!!

8 KANT S COMPROMISE We need to change the way we look at knowledge and say there are different types of truths. Distinction # 1: In addition to knowledge being 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

9 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.

10 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

11 KANT S COPERNICAN REVOLUTION 1. IMPACT ON SYNTHETIC A PRIORI TRUTHS Let s Look at an Example Truth : 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.

12 KANT S COPERNICAN REVOLUTION 1. IMPACT ON SYNTHETIC A PRIORI TRUTHS Let s Look at an Example Truth : 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)

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

14 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON SYNTHETIC A POSTERIORI TRUTHS

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18 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON SYNTHETIC A POSTERIORI TRUTHS

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22 KANT S COPERNICAN REVOLUTION: 2. IMPACT ON SYNTHETIC A POSTERIORI TRUTHS

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

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

25 KANT S COPERNICAN REVOLUTION All 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).

26 NEW THEORY OF THE UNIVERSE

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

28 NEW THEORY OF THE UNIVERSE Holographic Universe?

29 GROUP DISCUSSION What is Kant s Copernican Revolution and why does it lead Kant to believes that we cannot know the truth about reality as it is? Describe how this might lead some to believe that knowledge does not exist.

30 KANT AND KNOWLEDGE Do you think Kant s philosophy denies the existence of knowledge? He actually says that knowledge is possible, because knowledge is about how things appear to us, not about how things are in themselves. What does he mean by this? Without our mind to structure reality, we only have sensations, and sensation alone isn t knowledge. Knowledge is how we make sense of raw sensation.

31 KANT AND KNOWLEDGE Hence: Our brain creates knowledge. Does this make sense if knowledge is justified, true belief. Justified? Belief? True?