To those who are skeptical of science, such as Charles Fort and the Forteans, such episodes as Piltdown Man are taken to be proof that science is, more or less, bunk. To those who have a better understanding of the nature and limits of science, Piltdown episode is little more than a wrong turn down a series of roads which, despite such detours, eventually arrives at the right destination. But, above all, the forgery of the Piltdown Man demonstrates the fallibility and human quality of scientific knowledge. It demonstrates, too, the way theories and facts are related in science. Theories are the filters through which facts are interpreted.
Theories try to explain and make sense of facts.
On the other hand, facts are used to test theories. Gould notes that today a human cranium with an ape's jaw is considered to be extremely implausible and far-fetched. But in the early part of this century, anthropologists were imbued with the cultural prejudice which considered man's big brain as his ticket to rule, the main evolutionary feature that made it possible for man to develop all his other unique features. Since there was a pre-conceived notion that man's brain must have developed to its human size before other changes occurred in human structure, a human cranium with an ape's jaw didn't arouse as much suspicion as it would today. Once committed to a theory, we see what fits with the theory.