Recent years have seen the development of an approach both to general philosophy and philosophy of science often referred to as ‘experimental philosophy’ or just ‘X-Phi’. Philosophers often make or presuppose empirical claims about how people would react to hypothetical cases, but their evidence for claims about what ‘we’ would say is usually very limited indeed. Philosophers of science have largely relied on their more or less intimate knowledge of their field of study to draw hypothetical conclusions about the state of scientific concepts and the nature of conceptual change in science. What they are lacking is some more objective quantitative data supporting their hypotheses. A growing number of philosophers (of science), along with a few...