Abstract

Practices of concept-revision among scientists seem to indicate that concepts can be improved. In 2006, the International Astronomical Union revised the concept "Planet" so that it excluded Pluto, and insisting that the result was an improvement. But what could it mean for one concept or conceptual scheme to be better than another? Here we draw on the theory of epistemic utility to address this question. We show how the plausibility and informativeness of beliefs, two features that contribute to their utility, have direct correlates in our concepts. These are how inclusive a concept is, or how many objects in an environment it applies to, and how homogeneous it is, or how similar the objects that fall under the concept are. We provide ways to measure these values, and argue that in combination they can provide us with a single principle of concept utility. The resulting principle can be used to decide how best to categorize an environment, and can rationalize practices of concept revision.