Right from the beginning, that is, from the publication of Structure, Kuhn’s epistemology of science was an evolutionary epistemology of sorts. What changed over time was the extent to which his epistemology was an evolutionary epistemology. Later in his life, the evolutionary dimensions of his epistemology were extended and developed. Scientific change, he came to believe, was even more like evolutionary change than he had initially thought.

Kuhn first compares scientific change to evolutionary change in the final pages of Structure. There, Kuhn (1962a/1996) challenges the common assumption that science is moving toward a fixed goal set by nature. Instead, he claims that science is like evolution, pushed from behind. Kuhn claims that this change in perspective, that is, seeing that science is not moving toward a goal fixed by nature in advance, is the key to understanding the nature and dynamics of scientific change.