Epistemology

Sixth slideshow for an online course.

Transcript

1. Epistemology What do we know and how do we know it? George Matthews Spring 2017
2. What is knowledge?
3. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition
4. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! We often think of knowledge as the opposite of belief.
5. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! We often think of knowledge as the opposite of belief. ! But since we must also believe what we know, knowledge is really a type of belief that has something more than “mere belief.”
6. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! To know something is to have a belief that is also true.
7. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! To know something is to have a belief that is also true. ! Nobody really knew that the earth was flat – firmly held belief in a falsehood isn’t knowledge.
8. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! To know something is to have a belief that is also true. ! Nobody really knew that the earth was flat – firmly held belief in a falsehood isn’t knowledge. ! There is a difference between thinking you know something and actually knowing it.
9. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! Part of the difference involves having a good reason to believe what you claim to know.
10. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! Part of the difference involves having a good reason to believe what you claim to know. ! Thus we must also have a justification for a true belief to count as knowledge.
11. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition ! Part of the difference involves having a good reason to believe what you claim to know. ! Thus we must also have a justification for a true belief to count as knowledge. ! Lacking justifications our true beliefs would just be lucky guesses.
12. What is knowledge? To know something is to have a belief that is true and to have a justification or good reason to believe it. the standard definition NOTE: defining knowledge in this way does not guarantee that we actually have any knowledge, it just sets a standard that we must meet in order to legitimately claim to know something.
13. Plato’s Rationalism Plato: 428 - 348 BCE What we encounter in experience is an imperfect manifestation of a more perfect reality graspable by the mind alone.
14. Plato’s Rationalism Plato: 428 - 348 BCE If we see two square objects and conclude that they are equal in size we must rely on concepts like SQUARE and EQUALITY which we couldn’t pos- sibly have gotten from experience since no perfect squares or exactly equal things exist in the world of our experience.
15. Plato’s Rationalism Plato: 428 - 348 BCE The philosopher pursues wisdom by attempting to grasp these perfectly rational and ideal Forms mani- fest imperfectly in the world. Only after death will the soul encounter such Forms directly, once it is freed from the limitations of the body.
16. Plato’s Rationalism Plato: 428 - 348 BCE For Plato learning is actually recollection of ideas of the Forms already imprinted on the mind at birth.
17. Plato’s Rationalism Plato: 428 - 348 BCE Plato is a rationalist in that he thinks that reason takes priority over experience in attaining knowledge. His views greatly influenced Christianity via the “neo- Platonists” who equated contemplation of the Plato’s Forms with contemplation of the divine principle gov- erning the universe.
18. Descartes’ Rationalism Rene Descartes: 1596 - 1650 We do not have direct experience of reality but instead represent reality in our thoughts. The only guarantee that these representations are accurate is some set of thoughts that cannot be doubted.
19. Descartes’ Rationalism Rene Descartes: 1596 - 1650 Descartes relies on the method radical doubt to clear away all ideas that are less than certain in search of a sound foundation for knowledge.
20. Descartes’ Rationalism Rene Descartes: 1596 - 1650 He is thus led to wonder how he can tell whether he is awake or dreaming or even completely deceived by a massive illusion. He finds that the only thing that is certain is that as long as he is thinking or doubting he must exist – cogito ergo sum or “I think, therefore I am.”
21. Descartes’ Rationalism Rene Descartes: 1596 - 1650 But if he can be sure only that he himself exists, how can he find a way out of solipsism, locked inside his own head uncertain of anything “outside”? To find a way out Descartes relies on an argument that shows that a God exists who would never let him be deceived as long as he relies only upon “clear and distinct ideas” as the basis for claims about the world.
22. Descartes’ Rationalism Rene Descartes: 1596 - 1650 But Descartes’ argument has struck many people as being circular. We rely on clear and distinct ideas to prove that God exists, but God’s existence is required for us to be able to trust that clear and distinct ideas are in fact reliable.
23. Locke’s Empiricism John Locke: 1632 - 1704 The mind at birth is a blank slate – experience is our sole source of knowledge about the world.
24. Locke’s Empiricism John Locke: 1632 - 1704 Locke sets out to provide an account of the origins of all knowledge about the world, both particular and general ideas, in direct experience. For Locke we start out knowing nothing ad acquire all our knowledge through experience.
25. Locke’s Empiricism John Locke: 1632 - 1704 Locke was arguing against those rationalist philoso- phers like Descartes who claimed that we had certain “innate ideas” built in to our minds.
26. Locke’s Empiricism John Locke: 1632 - 1704 He sets out to show how even the most abstract ideas like SUBSTANCE, CAUSATION and IDENTITY are really attained in experience.
27. Locke’s Empiricism John Locke: 1632 - 1704 But can we really get ALL of our ideas from experi- ence? Is he mind really a “blank slate” at birth? If so why wouldn’t a chimpanzee raised among humans be able to talk and think like us?
28. Berkeley’s Idealism George Berkeley: 1685 - 1753 To be is to be perceived.
29. Berkeley’s Idealism George Berkeley: 1685 - 1753 Berkeley defends a rather strange sounding claim, that since we cannot make sense of what something would be like without actually perceiving it or imag- ining that we are doing so, we should stop assuming that anything can have an existence apart from being apprehended by some mind.
30. Berkeley’s Idealism George Berkeley: 1685 - 1753 On this view a tree falling in the forest with no perceiving mind present to wit- ness it is impossible.
31. Berkeley’s Idealism George Berkeley: 1685 - 1753 By why then do things seem to persist in between times we perceive them? Berkeley answers that there must be a mind perceiving things to keep them in the same state from one moment to the next and this mind is the mind of God.
32. Berkeley’s Idealism George Berkeley: 1685 - 1753 Berkeley is led to this extreme conclusion by think- ing through the basic empiricist idea that our knowl- edge comes from our experience alone – outside of experience we can say nothing about objects, hence objects that are not objects of someone’s experience are meaningless.
33. Hume’s Skeptical Empiricism David Hume: 1711 - 1776 All of our knowledge claims are either claims about ideas and their definitions, or claims about particular experiences. So generalizing about experience is always hazardous.
34. Hume’s Skeptical Empiricism David Hume: 1711 - 1776 Hume was interested in applying the scientific method to the study of human beings and was thus the first modern cognitive psychologist. Today he is most known for his skepticism about abstract con- cepts like CAUSATION, SUBSTANCE and SELF.
35. Hume’s Skeptical Empiricism David Hume: 1711 - 1776 For Hume all concepts we use to talk about what we ex- perience should themselves be based on direct experiences. But, with causality for example, we never actually experi- ence one thing causing another, instead we see one thing happen and then another. So we should give up the general idea of causation in his view.
36. Hume’s Skeptical Empiricism David Hume: 1711 - 1776 Like wise with the concept of a SELF or soul underlying and unifying our experiences and our personalities. Each of us experiences a series of particular events, but never do we encounter a SELF or soul having those experiences.
37. Hume’s Skeptical Empiricism David Hume: 1711 - 1776 Hume’s epistemology is based on his claim that all knowl- edge must either be a matter of the definitions of words or direct experiences. But is this claim itself something he knows by definition or from experience? It seems to be neither, so how can Hume claim that it is true?
38. Kant’s Constructivism Immanuel Kant: 1724 - 1804 Instead of assuming that our knowledge must conform to objects, we should suppose that objects must conform to our cognitive powers.
39. Kant’s Constructivism Immanuel Kant: 1724 - 1804 Kant responded to the debate between the empiricists and the rationalists by saying that both were right in certain ways and both wrong in other ways.
40. Kant’s Constructivism Immanuel Kant: 1724 - 1804 The empiricists were right in that the CONTENT of knowledge comes from experience – “Concepts with- out sensations are empty.”
41. Kant’s Constructivism Immanuel Kant: 1724 - 1804 The rationalists were right in that the FORM of knowledge comes from the mind – “Sensations with- out concepts are blind.”
42. Kant’s Constructivism Immanuel Kant: 1724 - 1804 Contemporary cognitive psychology is based on Kant’s theory of the constructive nature of knowl- edge. We can apply scientific methods to tease out what comes from experience and what comes from the mind in our experience and cognition. Is this circular?