I was doing some light reading this morning and I learned that Wittgenstein’s critique of the intension/extensional distinction begins in his early periods. I find that fascinating since, together with his critique of Russell’s philosophy of mathematics in the Tractatus, there seems to be a tension that the Stanford Encyclopedia of Philosophy does a much better job of explaining–sorry, I don’t have sufficient expertise in his early period to warrant an attempt 😉
If you’re interested, check out the Stanford Encyclopedia of Philosophy article, by Victor Rodych.
(source: Rodych, Victor, “Wittgenstein’s Philosophy of Mathematics”, The Stanford Encyclopedia of Philosophy (Spring 2007 Edition), Edward N. Zalta (ed.), URL = <http://plato.stanford.edu/archives/spr2007/entries/wittgenstein-mathematics/>.)