The most innovative and important parts of Bertrand Russell's Human Knowledge were the result of his first attempt in three decades to come to grips with the problem of induction, or, more generally, ‘non-demonstrative inference’. My purpose here is to argue that that work constituted giant progress on the problem; if I succeed, something will have been done to restore this work to its proper place in the history of philosophy and, correlatively, to rearrange that history.