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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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?