I'm going to be a senior in high school and I've found philosophy podcasts to be a great way to sample the thoughts of famous philosophers without having to drudge through esoteric forests of essays. Between listening to Philosophy Bites and Nigel Wharburton's reading of his book Philosophy: The Classics, I've become familiar with a bit of Hume and Kant. It is probable that I have misunderstood much of the material of the podcasts, so the material of this question does not reflect in any way the reliability of the sources. As I understand, Hume proposed the a priori and the a posteriori, the latter constructed by experience. Kant then respected the two categories but divided them into analytic a priori, synthetic a priori (new after Hume), and synthetic a posteriori. What interests me is the problem of "the missing shade of blue." Because all ideas originate from experience, even simple ones like fundamental colors (or shades of them), then are not all colors a posteriori? For they cannot be a priori in...

Although Hume does not himself use the terms 'a priori' and 'a posteriori', those categories do, roughly, correspond to the distinction that Hume draws between relations of ideas and matter of fact in the Enquiry Concerning Human Understanding . (The Enquiry Concerning Human Understanding is also referred to as the 'first Enquiry', as I will do in what follows, to distinguish it from the Enquiry Concerning the Principles of Morals , the 'second Enquiry'.) Now, by the by, but interestingly enough, Hume doesn't draw the distinction between relations of ideas and matters of fact, at least explicitly, in the earlier Treatise of Human Nature , much of whose first Book was recast in the first Enquiry, although he does draw a related distinction in Book 1, Part 3, Chapter 1 of the Treatise , between relations that depend on 'intuition' and 'demonstration', and have only to do with ideas, in contrast to other relations, which do not so depend on ideas, and thus do not admit of the sort of...