 It has been claimed by Psillos (2009) that the foregoing objection is misguided. The problem is this. There are the theories scientists currently endorse and there are the theories that had been endorsed in the past. Some (but not all) of them were empirically successful (perhaps for long periods of time). They were empirically successful irrespective of the fact that, subsequently, they came to be replaced by others. This replacement was a contingent matter that had to do with the fact that the world did not fully co-operate with the then extant theories: some of their predictions failed; or the theories became overly ad hoc or complicated in their attempt to accommodate anomalies, or what have you. The replacement of theories by others does not cancel out the fact that the replaced theories were empirically successful. Even if scientists had somehow failed to come up with new theories, the old theories would not have ceased to be successful. So success is one thing, replacement is another.