Plato

1. Plato Theaetetus

2. What is Knowledge? • In the Theaetetus, Socrates sets out to analyze what is knowledge or what does it mean to know something. • The view presented contributes to the standard definition of knowledge used within the philosophical tradition.

3. Plato • Socrates says, “Yes, actually it does seem plausible that the definition [of knowledge] itself is correct: because what knowledge could there be without an account [evidence or justification] and a correct judgment [truth]?” • For Plato, then, knowledge is a belief that is true and that one can give an account of. • This has led to the definition of knowledge as justified true belief.

4. Knowledge as Justified True Belief • What does it mean ‘to know’ something? • One way to get at the notion of knowledge is to compare it with other similar notions such as belief. • “I believe that …” • “I know that…”

5. Belief vs. knowledge • When someone says they know something, they express a sense of certainty. • When someone says they believe something they express a commitment based more on faith and trust than certainty. • For instance, John says, “I know that Matt stole your computer.” John seems to be asserting that he not only believes it, but also that he has some sort of evidence to justify his belief.

6. Knowledge and Justification • Knowledge therefore entails something that gives one certainty about the truth of a claim. • We call this justification or evidence. • Matt stole your computer is either true or false. • The more evidence that one has for the truth of the claim the more reason we have to believe that the claim is true.

7. Knowledge, Belief, Evidence, and Rationality • Knowledge therefore requires two things: (1) belief and (2) evidence. • Both beliefs and evidence come in DEGREES. • Therefore, you can believe things with different degrees of strength. • You can also have different degrees of evidence (from very little, to a preponderance or more than 50%, to beyond all reasonable doubt, to beyond all possible doubt.) • A reasonable person proportions the strength of his or her belief with the amount of evidence he she has for the truth of the belief.

8. Knowledge and Truth • If one believes something and has excellent evidence for the truth of the belief, at time 1 (T1), can we conclude that they have knowledge? • What if, at time 2 (T2), she discovers that the belief is false? • Can we conclude that the person had knowledge at T1 or at T2?

9. Knowledge and Truth • NO • To have knowledge of the truth of a proposition, requires that the proposition be TRUE. • In the above case, we would say that the person thought they knew at T1 but in fact did not know. And they do not know at T2.

10. Example • Imagine that you are in a classroom with no windows but hear thunder and rain. The sounds are unmistakably clear. • You are justified in believing that it is raining outside. Later when you walk out, you discover that it is very sunny and that the sound you heard was from a movie in the next room. In this case, we would not conclude that “you knew that it was raining” because you cannot know something is true that is false. • You had a justified belief, but the belief was not true. Therefore, you did not have knowledge.

11. Plato on Justification • Plato discusses what “to give an account of something” means. • Socrates says, “But let’s not, on their account, forget to look into the question before us: what, exactly, is meant by saying that an account, if added to a true judgment, becomes the most perfect of knowledge.”

12. “to give an account” • Plato's central idea makes sense, because if someone claims that they know something, then they should be able to explain it to another person. • If you are in a study group and someone says they know question 7, and you ask them to explain it (give an account) to the group, you would expect them to be able to do so.

13. “to give an account” • 1) To make plain through speech and expression. • 2) To give the parts (elements) that compose a thing. • 3) to give some mark that distinguishes a thing one is asked about from all other things.

14. 1) To make plain through speech and expression • This is one interpretation of giving an account, but it would not be sufficient for knowledge. • The fact that one can explain or describe a thing does not mean they know it. • For instance, you might be able to explain what a black hole is but that would not mean that you know all there is to know about black holes.

15. 2) To give the parts (elements) that compose a thing. • To know something can also be interpreted as knowing the parts of a thing or what the thing is composed of . • I know water because I know that water is H2O, which are the basic elements of water. • However, can we say that this exhaust our conception of knowledge? Is knowledge only this?

16. Complexes and elements • At the beginning of the Dialogue Plato engages in an interesting discussion concerning the relationship between the whole and its parts. • Is the whole the sum of its parts? (for instance, is a human, simply the sum total of its parts?) • If it is not, then it would seem impossible that you could explain, define or know the whole by simply explaining, defining or knowing the parts.

17. A Paradox • Plato’s analysis is very complicated, and he raises more problems than solutions. • For instance, if a whole complex thing is only the sum of its parts, and the elementary parts that compose a complex thing are not knowable, since they cannot be broken down any further, then, the whoel complex thing is also unknowable. • If the whole is not the sum total of its parts then the whole is something unique and cannot be broken down into parts. But if this is the case then it too is elementary and unknowable.

18. A thing cannot be known through its parts • It seems clear that knowing the parts that constitute a thing does not exhaust our conception of knowledge. • Is knowledge only this?

19. 3) to give some mark that distinguishes a thing • To know a thing certainly entails knowing a things parts, but it also entails more than this. • For instance, to know what a human being is, entails knowing the properties and that make up a being human. • However, this interpretation of ‘giving an account’ claims that what is central in knowing is recognizing and identifying a thing’s essential property, i.e., what makes the things unique and special. • In the case of human beings, this would mean knowing humans’ property of rationality.

20. Conclusion • In the Theaetetus ,Plato presents here a definition of knowledge as justified true belief. This definition is still relevant today in philosophy. • The heart of this definition is the conception of justification or what Plato refers to as “to give an account of”. • Plato, analyzes what is meant by justification or to give an account, and presents three interpretations. The three are important parts of knowledge but none seems to capture the entire meaning of knowledge. • We are left with the problem unresolved!