 The first is his Philosophy of Mathematics, especially as set forth in “Proofs and Refutations” (1963–64) a series of four articles, based on his PhD thesis, and written in the form of a many-sided dialogue. These were subsequently combined in a posthumous book and published, with additions, in 1976. The title is an allusion to a famous paper of Popper’s, “Conjectures and Refutations” (the signature essay of his best-known collection), in which Popper outlines his philosophy of science. Lakatos’s point is that the development of mathematics is much more like the development of science as portrayed by Popper than is commonly supposed, and indeed much more like the development of science as portrayed by Popper than Popper himself supposed.