I argue the best primer is Feynman's "The meaning of it all: Thoughts of a citizen-scientist" and "The Pleasure of Finding Things Out". I'm not just linkbaiting HN's love for Feynman: Feynman was an active, practicing scientist and besides being introspective, he had a great knack for explaining things in a perspective accessible to non-scientists. Kuhn is worth reading, though if you are a scientist and want to get a more-in-depth analysis of philosophy of science that is laid out formally.