The two other commentators, being, like Professor Laudan, scholars, have commented on the whole of his book. As a mere philosopher, I may perhaps be forgiven if I get little further than the first chapter of Progress and Its Problems.

We know that the practice of science increases our knowledge and understanding of things and events, and consequently our capacity to predict and control them. That is why the practice of science interests philosophers who are concerned to say how such knowledge and understanding, such capacity for prediction and control, can be acquired. It challenges them to show why scientific practice should deliver these cognitive goods. Some who decline the challenge, or fail to meet it, may deny that it does deliver the goods; but their conscious practice, of preferring aircraft to broomsticks for flight and telephones to telepathy for communication, belies the sincerity of their denials.