The tripartite theory of knowledge

1. The tripartite theory of knowledge Michael Lacewing enquiries@alevelphilosophy.co.uk

2. Three types of knowledge • Acquaintance knowledge • I know Oxford • Ability knowledge • I know how to ride a bike • Propositional knowledge • I know that elephants are heavier than mice. • A proposition is a declarative statement, or more accurately, what is expressed by a declarative statement • Propositions can go after the phrases ‘I believe that…’ and ‘I know that…’ • We are only discussing propositional knowledge.

3. Justified true belief • ‘I know that p’: • The proposition ‘p’ is true; • I believe that p; and • My belief that p is justified. • I know that p if these three conditions are fulfilled. And these conditions are fulfilled if I know that p.

4. Necessary and sufficient conditions • Each condition is necessary for knowledge • You can’t have knowledge without each condition being true. • The three conditions together are sufficient for knowledge • You don’t need anything more for knowledge than each condition being true. • So knowledge and justified true belief are the same thing.

5. Is justification necessary? • Is knowledge more than true belief? • True beliefs can be held on irrational grounds (prejudice) or just be lucky guesses (astrology) • Knowledge needs a reason, evidence –justification. • However, we sometimes use the word ‘know’ to mean ‘believe truly’ • But this doesn’t capture what we mean by knowledge, strictly speaking.

6. Is truth necessary? • Could knowledge be justified belief? • We don’t normally say someone can know what is false • E.g. ‘I know that flamingos are grey’ – no, I don’t – I’m mistaken (I think I know, but I’m wrong). • But did people used to ‘know’ that the Earth is flat? • What about our ‘knowledge’ of Newtonian physics? • This is, strictly speaking, false, but works well when not moving at speeds close to the speed of light.

7. Is truth necessary? • Newtonian physics is roughly true • We know them, roughly speaking. • However, the Earth is not even roughly flat • People did not know the Earth is flat – they were mistaken.

8. Doing away with truth? • Kuhn (The Structure of Scientific Revolutions): science proceeds by replacing one ‘paradigm’ by another • We can’t compare the two paradigms so as to say that one is false, the other true • Because changes in paradigms involve new concepts • And there is no ‘theory-neutral’ way of describing the evidence.

9. Doing away with truth? • How scientists describe what they observe depends on the concepts they use. • The main concepts of a paradigm acquire their meaning in relation to the paradigm as a whole. • Therefore, a different paradigm, even if it uses the same term, interprets the concept differently, because it plays a new and different role. • Therefore, different paradigms are talking about different things. • There is no neutral way of describing the world. • Therefore, we cannot compare different paradigms’ claims to say that one is more ‘correct’ or ‘true’ than another, as they could both be correct in their own terms.

10. Objection • We cannot explain science’s success unless we think it is getting closer to objective truth • Reply: science keeps solving puzzles that face it, but isn’t getting ‘closer’ to ‘the truth’. • There have been no paradigm shifts • There is always overlap in methodology and evidence, so we can always compare paradigms. • We can’t talk about Truth – independent of our concepts; but we can talk about truth – claims that are true or false. • Knowledge can still be justified true belief.

11. Is belief necessary? • Example: John is very nervous in an exam, and has no confidence in his answers. But his answers are correct, and through his learning, not luck • John knows the answer, but doesn’t believe the answer. • Reply • John doesn’t know the answer • John does know the answer and has an unconscious belief.

12. Is belief necessary? • Williamson: knowledge is not a type of belief. • Compare perception and hallucination • You only see the tea on the table if the tea is on the table; perception is ‘factive’ • Hallucinating the same scene is a completely different type of mental state • Perception is not hallucinating + extra conditions. • Knowing is also factive (p is true), belief is not factive.

13. Knowledge and belief • Every attempt to add conditions to belief to turn it into knowledge has failed. • Knowledge is unanalysable • There are different kinds of knowing – perceiving, remembering… • We should understand belief in terms of knowledge • To believe that p is to take p to be true, i.e. to treat p as if you know that p. • Objection: when I make a mistake, I think I know that p, but only believe that p – why, if knowledge is not belief?