‘Revolution in Permanence’: Popper on Theory-Change in Science

Summary

Introduction

Science, and in particular the process of theory-change in science, formed the major inspiration for Karl Popper's whole philosophy. Popper learned about the success of Einstein's revolutionary new theory in 1919 (the same year in which his discontent with Marxism and Freudianism reached crisis-point), and Einstein ‘became a dominant influence on my thinking–in the long run perhaps the most important influence of all.’ Popper explained why:

In May, 1919, Einstein's eclipse predictions were successfully tested by two British expeditions. With these tests a new theory of gravitation and a new cosmology suddenly appeared, not just as a mere possibility, but as an improvement on Newton–a better approximation to the truth … The general assumption of the truth of Newton's theory was of course the result of its incredible success, culminating in the discovery of the planet Neptune … Yet in spite of all this, Einstein had managed to produce a real alternative and, it appeared, a better theory … Like Newton himself, he predicted new effects within (and without) our solar system. And some of these predictions, when tested, had now proved successful.

(‘IA’, p. 28)

Popper saw the development of science, through the process of change in accepted theory, as the exemplification of ‘the critical approach’. Science is rational because all of its theories are open to empirical criticism, and because it stands ready to reject any such theory if criticism succeeds, no matter how impressively the theory had performed in the past.