  At bottom, despite his talk of ideal type and equilibrium, Duhem’s science is not universalistic. The strength of his analysis is that there is no single direction within science that each individual must follow. For that, one would need to ground physics in a particular metaphysics—which Duhem explicitly rejects with his instrumentalism—or rather, to be guided by what one projects metaphysics will look like over the long run. Unfortunately, Duhem took this last thought too rigidly and ultimately condemned all innovations as breaking with the past, either due to an excess of esprit de géométrie, as with non-Euclidean geometry and relativity, or an excess of esprit de finesse, as with electron theory. But his philosophy of science itself contained the seeds of scientific pluralism, which are the foundations of the Duhem thesis, that is, the thought that there are many legitimate and disparate ways of proceeding in science.