 A degenerating research programme, on the other hand (unlike the theories of Newton and Einstein) either fails to predict novel facts at all, or makes novel predictions that are systematically falsified. Marxism, for example, started out as theoretically progressive but empirically degenerate (novel predictions systematically falsified) and ended up as theoretically degenerate as well (no more novel predictions but a desperate attempt to explain away unpredicted “observations” after the event).