"In 1962, Thomas Kuhn published a groundbreaking book entitled The Structure of Scientific Revolutions. In it, he argued that the progress of science is not gradual but (much as we now think of biological evolution), a kind of punctuated equilibrium, with moments of epochal change. When Copernicus explained the movements of the planets by postulating that they moved around the sun rather than the earth, or when Darwin introduced his ideas about the origin of species, they were doing more than just building on past discoveries, or explaining new experimental data. A truly profound scientific breakthrough, Kuhn notes, "is seldom or never just an increment to what is already known. Its assimilation requires the reconstruction of prior theory and the re-evaluation of prior fact, an intrinsically revolutionary process that is seldom completed by a single man and never overnight." Kuhn referred to these revolutionary processes in science as "paradigm shifts", a term that has now entered the language to describe any profound change in our frame of reference."http://tim.oreilly.com/opensource/paradigmshift_0504.html