 There is another respect in which Lakatos’s Demarcation Criterion is more forgiving than Popper’s. For Popper, if a theory is not falsifiable, then it’s not scientific and that’s that. It’s an either/or affair. For Lakatos being scientific is a matter of more or less, and the more the less can vary over time. A research programme can be scientific at one stage, less scientific (or non-scientific) at another (if it ceases to generate novel predictions and cannot digest its anomalies) but can subsequently stage a comeback, recovering its scientific status. Thus the deliverances of the Criterion are matters of degree, and they are matters of degree that can vary from one time to another. We can seldom say absolutely that a research programme is not scientific. We can only say that it is not looking very scientifically healthy right now, and that the prospects for a recovery do not look good. Thus Lakatos is much more of a fallibilist than Popper. For Popper, we can tell whether a theory is scientific or not by investigating its logical implications. For Lakatos our best guesses might turn out to be mistaken, since the scientific status of a research programme is determined, in part, by its history, not just by its logical character, and history, as Popper himself proclaimed, is essentially unpredictable.