K knows that s is F = K's belief that s is F is caused (or causally sustained) by the information that s is F.Dretske argues that this is a better definition of knowledge than the 'traditional'
Knowledge is justified true beliefYou have to take Dretske's definition together with his definition of information.
Consider the atomic theory of matter. Now, in what follows, you have to accept all sorts of 'suspension of skepticism', and it really needs reams of footnotes and caveats, but I think it does provide a valuable insight.
- Did Democritus know that matter is structured into atoms?
- Democritus did NOT know, on either definition. Although the belief was true, it was not justified because he didn't have any (modern, scientific) evidence. Similarly, Democritus's belief was not caused by the information that matter is structured into atoms
- Did Rutherford know that matter is structured into atoms?
- Yes, on both definitions. The belief was true, and it was justified by the experimental evidence - which was the information from his experiment.
- Did a student of Democritus know that matter is structured into atoms
- This I think is the key one, because I think on the 'justified true belief' a student of Democritus did know. That is, if we are going to allow anyone to learn anything 'second hand', from a teacher, then we must allow the possibility that a student of Democtritus is justified in believing his teacher. But, he does not know anything of the sort in Dretske's definition, because he did not receive the information that matter is structured into atoms.
- Do I know that matter is structured into atoms?
- Well, yes, I think I do know that, on both definitions. Except, of course, that there's a bit of the skeptic in me (especially, dogmatic scientific statement), but I did say above that there were all sorts of caveats and footnotes needed, and Dretske does discuss the position of the skeptic