Post on 01-Apr-2015
Three kinds 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.
Justified true belief
• Analyses knowledge in terms of necessary and sufficient conditions
• ‘I know that p’:– The proposition ‘p’ is true;– I believe that p; and– My belief that p is justified.
Necessary and sufficient conditions
• Each condition is necessary for knowledge.• The three conditions together are sufficient for
knowledge.
The appeal of JTB
• I can’t know what is false.• I can’t know a proposition that I don’t
believe to be true.• Beliefs that are irrational or aren’t
based on the evidence aren’t knowledge.
The Gettier problem
• Justification is usually a matter of evidence, e.g. what I remember.
• Gettier: It is possible to have JTB without knowledge.
Infallibilism
• Since I can’t know something false, if I know that p, it is not possible that I could have made a mistake.
• Justified belief is true belief. If my belief could be false, then it is not justified.
• Is this too strong?
Development• Condition 4: My justification for
believing that p ‘stands up to the facts’.• I know that p if my justification for
believing that p is ‘undefeated’.
Objection
• Is this enough for knowledge?• Or should we consider what the facts
might have been?
That’s
Judy!
Case 1: Meeting Judy
That’s
Judy!
Case 2: Meeting Trudy
Reliabilism
• S’s belief that p is justified if and only if S’s belief that p is produced by a reliable process– Usually, this involves a causal connection
between p and the belief that p.
• Reliabilism rejects the view that justification requires evidence. It is not the grounds that the person is able to produce that make a belief knowledge; it is the source of the belief.
Reliabilism and Gettier
• My memory of where I put my watch is reliable in normal situations. But this way of knowing where my watch is is not reliable in a Gettier situation. So I don’t have knowledge.
• What about Judy and Trudy? Even though recognising people is normally reliable, I’d still think Trudy was Judy. So I’m not reliable at recognising Judy, because she has a twin living locally; so even when I recognise Judy as Judy, I don’t know it’s Judy.