The Knowledge Machine: How Irrationality Created Modern Science

by Michael Strevens

Kuhn scandalized the world of science with this picture of revolutionary scientific change. Previous historians and philosophers had seen scientific change as a largely rational process: the ideas of Copernicus, of Kepler, of Galileo, of Newton, however radical, were accepted because they were so clearly superior to the old ideas, both in their predictive successes and in their explanatory beauty. If Kuhn is right, then this older, more dignified conception of scientific progress must be wrong, for in Kuhn’s view, it is impossible to compare paradigms: “When paradigms enter, as they must, into a debate about paradigm choice, their role is necessarily circular.” Perhaps if you had two brains as you have two hands, you could weigh one paradigm against another. But you have only a single brain, and a single brain is capable of grasping only a single paradigm. You cannot simultaneously appreciate the merits of the Aristotelian and the Newtonian worldviews any more than you can simultaneously be a fervent Muslim and a devoted Roman Catholic. At the height of his rhetoric, Kuhn wrote that the Aristotelian and the Newtonian live in different worlds; you can live in one world or the other, but you cannot be in two different places at the same time. A rational comparison of competing paradigms is therefore humanly impossible. In the place of logical evaluation, Kuhn posits a leap of faith: a giddy jump through ideologically empty space from the traditional view of things to the rev...