 Apart from the fact that, for Lakatos, a) it can be rational to persist with a “falsified” theory, and indeed with theory that is actually inconsistent—both anathema to Popper—and that b) that for Lakatos “all theories are born refuted and die refuted” (S&amp;P: 5) so that there are no unrefuted conjectures for the virtuous scientist to stick with (thus making what Popper would regard as good science practically impossible), Lakatos’s methodology of scientific research programmes replaces two of Popper’s criteria with one. For Popper has one criterion to distinguish science from non-science (or science from pseudoscience if it is a theory with scientific pretensions) and another to distinguish good science from bad science. In Popper’s view, a theory is scientific if it is empirically falsifiable and non-scientific if it is not. Being scientific or not is an absolute affair, a matter of either/or, since a theory is scientific so long as there are some observations that would falsify it. Being good science is a matter of degree, since a theory may give more or less hostages to empirical fortune, depending on the boldness of its empirical predictions. For Lakatos on the other hand, non-science or pseudo-science is at one end of a continuum with the best science at the other end of the scale. Thus a theory—or better, a research programme—can start out as genuinely scientific, gradually becoming less so over the course of time (which was Lakatos’s view of Marxism) without altogether giving up the scientific ghost. Was the Marxism of Lakatos’s day bad science or pseudo-science? From Lakatos’ point of view, the question does not have a determinate answer, the point being that it isn’t good science since it represents a degenerating research programme. But although Lakatos evidently considered Marxism to be in bad way, he could not consign it to the dustbin of history as definitively finished, since (as he often insisted) degenerating research programmes can sometimes stage a comeback.