"... if a theory has found favour with a scientific community, it is the anomalous finding rather than the theory itself which is discredited. This is... exactly what happened in the experiment with the bristle. It was only when the pulmonary circulation was accepted as an established fact that the results of this experiment could be recognised as significant. Meanwhile, as is so often the case, it was more convenient to make an ad hoc modification of the existing theory. The history of science is full of such examples. If a theory is persuasive enough - and the reasons for any given theory being so persuasive are often hard to list - scientists will accommodate inconsistent or anomalous findings by decorating the accepted theory with hastily improvised modifications. Even when the theory has become an intellectual slum, perilously propped and patched, the community will not abandon the condemned premises until alternative accommodation has been developed."