In the early sixties there broke out a fierce controversy concerning rationality in science which was labelled as the Popper-Kuhn controversy. It can be conceived in terms of the rationalism-relativism opposition. This may seem dubious, for the proper contrast to rationalism is irrationalism, and the one to relativism is absolutism. What is at issue, however, is whether scientific change comes about in consequence of argument or in consequence of-to use Kuhn's favourite dictum-conversion. The notion of argument does not involve here (...) anything absolute, while the one of conversion is intended to cover not merely the idea of irrationality of change, but the idea of self-authentication and constitution as one among many possible patterns of rationality. Thus the main message is that of break of communication between otherwise rational agents and not of their apparent irrationality. These are my reasons for thinking this unusual opposition better than the usual ones pointing at the substance of the controversy. I think also this opposition has in fact been implicit in the resulting debate. This explains, for instance, why in the first decade of the debate Feyerabend was commonly perceived as Kuhn's comrade and, consequently, largely misunderstood. Conflation of two different oppositions into one, on the other hand, results in some obscurity. This is perhaps why different commentators have rather freely qualified some participants of the debate to one or other faction. Among those who have been subjected to such a treatment there are found, in the first place, the authors of such mediational conceptions of the seventies as Lakatos (methodology of scientific research programmes), Sneed and Stegmiiller (non-statement view), Laudan (research traditions), and, in my country, Amsterdamski (ideals of science). It may well have been expected that Larry Laudan, who has recently put forward a new mediational conception of his own (see Laudan [1984]), again will be treated in the same way. This is due to the clear Popperian and Kuhnian inspirations of his work and his fidelity to his masters which is surprisingly great consider. (shrink)