 To begin with, the unit of scientific evaluation is no longer the individual theory (as with Popper), but the sequence of theories, the research programme. We don’t ask ourselves whether this or that theory is scientific or not, or whether it constitutes good or bad science. Rather we ask ourselves whether the sequence of theories, the research programme, is scientific or non-scientific or constitutes good or bad science. Lakatos’s basic idea is that a research programme constitutes good science—the sort of science it is rational to stick with and rational to work on—if it is progressive, and bad science—the kind of science that is, at least, intellectually suspect—if it is degenerating. What is it for a research programme to be progressive? It must meet two conditions. Firstly it must be theoretically progressive. That is, each new theory in the sequence must have excess empirical content over its predecessor; it must predict novel and hitherto unexpected facts (FMSRP: 33). Secondly it must be empirically progressive. Some of that novel content has to be corroborated, that is, some of the new “facts” that the theory predicts must turn out to be true. As Lakatos himself put the point, a research programme “is progressive if it is both theoretically and empirically progressive, and degenerating if it is not” (FMSRP: 34). Thus a research programme is degenerating if the successive theories do not deliver novel predictions or if the novel predictions that they deliver turn out to be false.