This paper had its origins in my responding to a PESA conference paper, “The Unity of Knowledge’’, written by Colin Evers and Jim Walker. With that paper’s critique of Hirst on logically distinct forms of knowledge I am in agreement, as indeed I am with the epistemological doctrine briefly set out in the final sections of the paper. There an account is offered “of the growth of knowledge as theory competition in view of practical problems and touchstone”. As Walker and Evers advance their view, one notes the Lakatosian marks of a research programme which leads to a “progressive problemshift”. It is along such lines that I think we need to seek to solve the riddle about knowledge set by our acknowledged fallibility.