New paradigms succeed thanks to the arrival of a new generation, not because of the conversion of the existing one

How, then, are scientists brought to make this transposition? Part of the answer is that they are very often not.

Copernicanism made few converts for almost a century after Copernicus’ death. Newton’s work was not generally accepted, particularly on the Continent, for more than half a century after the Principia appeared. Priestley never accepted the oxygen theory, nor Lord Kelvin the electromagnetic theory, and so on.

The difficulties of conversion have often been noted by scientists themselves. Darwin, in a particularly perceptive passage at the end of his Origin of Species, wrote: “Although I am fully convinced of the truth of the views given in this volume . . . , I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. . . . [B] ut I look with confidence to the future,—to young and rising naturalists, who will be able to view both sides of the question with impartiality.”

And Max Planck, surveying his own career in his Scientific Autobiography, sadly remarked that “a new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”