 To Popper’s uncompromising deductivism he opposed the claim that corroboration, the core of Popper’s falsificationist methodology, is a non-demonstrative kind of inference: “Modus tollens without corroboration is empty; modus tollens with corroboration is induction” (Salmon 1968a: 28; see also Salmon 1981 [1988a]). A number of Salmon’s papers published in the Fifties and Sixties argued against various attempts to deny or dissolve the problem of justifying induction, including those of A.J. Ayer, M. Black and P. Strawson (Salmon 1957, 1963b, 1965, 1978b). By contrast, he took seriously Hume’s argument showing the impossibility of giving a logical solution to the problem of the justification of induction. Adopting Herbert Feigl’s distinction between validation and vindication (Feigl 1950), Salmon embraced a pragmatic approach according to which induction is justified in terms of the knowledge-extending function to which it happens to be necessary.