1. Epistemology
The branch of philosophy that critically evaluates the nature, methodology, limitation, and origin of human knowledge.

2. Explicit vs. Implicit Knowledge
The knower is aware of the relevant state of knowledge.
Implicit
Knowledge that is hidden from consciousness. Most of our knowledge is of this kind.

3. Propositional vs. Sentential Knowledge
Sentence: a grammatical unit that is syntactically independent. In its written form, it is an object having a shape accessible to sensory perception.
Proposition: the sense or meaning of a sentence.

4. Compare: English vs. German Sentences
“Europe has many countries and languages.”
“Europa hat viele Länder und viele Sprachen.”

5. “I know that Austin is the capital of Texas.”
Our focus will be on sentential knowledge: knowing that something is the case (“I know that ”).
We use the word “know” a lot in everyday discourse. Whether those usages are justified or not is a separate issue:
“I know that Austin is the capital of Texas.”
“I know that there is intelligent life elsewhere in the observable universe.”
“I know that the Golden State are going to win the 2017 NBA Championship.”
“I know that Donald Trump will win the Presidential election.”

6. Tripartite Conception of Sentential Knowledge
According to Plato and Kant, sentential knowledge has three individually necessary and jointly sufficient components:
Justification
Truth
Belief

7. Tripartite Conception of Sentential Knowledge
Sentential knowledge is justified true belief, argued Plato and Kant.
Criticisms: Not all philosophers are satisfied with the tripartite conception, however. See, for example, Edmund Gettier’s article, “Is Justified True Belief Knowledge?”

8. Belief
This requires that anyone who knows that p (where “p” stands for any statement) must believe that p.

9. Truth
Our concept of knowledge seems to have a factual requirement: we genuinely know that p only if it is the case that p.

10. Justification
Knowledge requires that the satisfaction of its belief condition be “appropriately related” to the satisfaction of its truth condition.

11. Justification
When are we epistemically justified in accepting a statement?
Four theories of justification:
Rationalism
Empiricism
Transcendental Idealism
Skepticism

12. Justification Empiricism From empirical observations. Rationalism
From our reasoning powers.
Transcendental Idealism
Combination of the above two theories.
Skepticism
Limits to our knowledge?

13. Theory #1: Empiricism
The position that knowledge has its origins in, and derives all of its content from, experience.

14. Empiricist Philosophers
Aristotle
John Locke
George Berkeley
David Hume
Bas van Fraassen

15. Empirical Knowledge Empirical:
based on experience; derived ultimately from the five senses.

16. Empirical Knowledge A posteriori:
A proposition is said to be justified a posteriori if its epistemic justification, the reason or warrant for thinking it to be true, depends on sensory experience.

17. Examples of A Posteriori Knowledge
Halley’s comet returns to Earth every seventy-six years.
At the surface of the earth, objects fall at the accelerating rate of 32 feet per second per second.
When oxygen and hydrogen burn, they produce water.
The universe is 13.7 billion years old (± 200 million years).

18. Empiricists’ Critique of Rationalism
Our reasoning ability is defective. It can lead us astray (e.g., logical fallacies).
Empiricists frown upon “arm- chair” approach to knowledge acquisition.

19. Empiricists’ Critique of Rationalism
Why not put an idea to the test?
Adam Savage and Jamie Hyneman

20. Philosopher Spotlight: John Locke
The mind is a blank slate.
Primary qualities
Mass, size, shape
Secondary qualities
Color, smell, texture

21. Philosopher Spotlight: David Hume
Impressions
All our more lively perceptions, when we hear, or see, or feel, or love, or hate, or desire, or will.
Ideas
The less lively perceptions of which we are conscious, when we reflect on any of those sensations or movements above mentioned.

22. Theory #2: Rationalism
The position that reason alone, without the aid of sensory information, is capable of arriving at some knowledge.

23. Rationalist Philosophers
Plato
St. Augustine
Benedict Spinoza
Anne Conway
Gottfried Leibniz
Georg Hegel
Rene Descartes

24. Rationalist Knowledge
Also known as a priori knowledge.
A priori: A proposition is said to be justified a priori if its epistemic justification (i.e., the reason or warrant for thinking it to be true) does not depend on sensory experience.

25. Examples of A Priori Knowledge
“All bachelors are unmarried.”
“All squares have four sides.”
“A rose is a flower.”
(Analytic propositions)
“7 + 5 = 12”
(Mathematical propositions)
“Nothing can both be and not be at the same time in the same respect.”
(Logical propositions)

26. Rationalists’ Critique of Empiricism
Empirical information (i.e., one that is based on our physical senses) cannot be trusted because our senses can deceive us.

27. Philosopher Spotlight: Rene Descartes
“Father of Modern Philosophy”
Mathematician
Wrote Meditations

28. Rene Descartes Doubt and Reason
Sense perceptions have deceived him in the past.
Mathematics
Indubitable (beyond doubt)
Incorrigible (beyond change)
Cogito ergo sum: “I am thinking, therefore I exist.”

29. He employed the method of doubt to arrive at certainty.
Rene Descartes
Descartes is often confused for a skeptic, but he doesn’t rest on skepticism.
He employed the method of doubt to arrive at certainty.

30. Rene Descartes
Certainty is a state of the mind, while reality is the way the world is.

31. Clear and Distinct Ideas
We have a clear idea of something when we know its nature or essence so well that we can identify it.
We have a distinct idea of something when we can distinguish it from other things.
The mind is the ultimate basis of knowledge.

32. Thought Experiments
Rene Descartes: Evil Genius (Deceiving Demon) hypothesis
Hilary Putnam: Brain-in-Vat hypothesis
Sleep hypothesis: How do you know you’re not sleeping at home dreaming that you’re sitting in a philosophy class at school?

33. Movies such as The Matrix (1999) or Transcendence (2014) illustrate these hypotheses

34. It is a neuro-interactive simulation.
What is the Matrix?
It is a neuro-interactive simulation.
A computer-generated dream world, built to keep humans under control.

35. As long as the Matrix exists, the human race will never be free.

36. The Matrix
Your knowledge of the world is merely the result of electrical signals interpreted by the brain.

37. Could you be living in the Matrix?
If you were in Neo’s shoes, would you take the blue pill or the red one?

38. Rationalist or Empirical Knowledge?
“The sum of the interior angles of a triangle equals 180 degrees.”
“The shortest distance between two points is a straight line.”
“The average period of gestation for humans is forty weeks.”
“All U.S. Presidents have been men.”

39. Theory #3: Transcendental Idealism
In epistemology, the view that the form of our knowledge of reality derives from reason but its content comes from our senses.

40. Philosopher Spotlight: Immanuel Kant
Critique of Pure Reason
Critical mediator between rationalism and empiricism

41. Immanuel Kant
“But though all our knolwedge begins with experience, it does not follow that it all arises out of experience. For it may well be that even our empirical knowledge is made up of what we receive through [sense] impressions and of what our own faculty of knowledge supplies from itself.”

42. Transcendental Principle of Unity
When you look at the room around you, you don’t see a blooming confusion of colors and lines and shapes floating and changing in front of your eyes. Instead, you see a desk, a book, a sheet of paper, and the walls of a room. Somehow the sensations that continually play in your vision get arranged by your mind into solid objects.

43. Transcendental Principle of Unity
Kant holds that the mind possesses mental “categories.” These categories organize our perceptions into the orderly world we experience.

44. Transcendental Principle of Unity
The world as we experience it results in part from the sensations provided by our senses, and in part form the workings of the mind. The senses provide the content or stuff of experience; the mind provides its form or orderly structures.

45. Phenomenal vs. Noumenal
Kant called the world that our minds construct and that we seem to see around us the “phenomenal” world.
The world as it might really be apart from our mind he called the “noumenal” world.

46. Phenomenal vs. Noumenal
Clearly, we can never know what the noumenal world is really like. All we can ever know is the phenomenal world that we perceive after the mind has organized it by putting our sensations together.

47. Copernican Revolution
Kant’s revolutionary claim that the world must conform to the mind is often referred to as the Copernican revolution in knowledge.
Geocentricism ⇒ Heliocentricism
Mind must conform to world ⇒ World must conform to the mind.

48. Theory #4: Skepticism
Are there any limits to our knowledge?
The more restricted we take the limits of knowledge to be, the more skeptical we are.

49. Skepticism
In epistemology, the view that varies between doubting all assumptions until proved and claiming that no knowledge is possible.

50. Skepticism
Many skeptics have restricted their skepticism to a particular domain of supposed knowledge, such as the following:
External world
Other minds
Past and future
Unperceived objects

51. Examples
Do you really “know” anything before you were born? [“I know that I had lived previous lives.”]
Do you “know” anything about the future? [“I know that I will live forever.”]
Do you “know” anything about current events happening in other parts of the world? [“I know that my car is safely parked outside.”]

52. Skepticism in the public sphere: Michael Shermer
The Skeptics Society
Devoted to the promotion of science and critical thinking and the investigation of extraordinary claims and revolutionary ideas.

53. Skepticism in the public sphere: James Randi
His organization used to offer a one million- dollar prize to anyone who can show, under proper observing conditions, evidence of any paranormal, supernatural, or occult power or event.

54. Leprechauns
Witches