Non-Epistemic Simplicity

This chapter examines five claims about simplicity: (i) that theories are underdetermined by evidence, and so must be selected on the basis of simplicity; (ii) that to do science you must presuppose that nature is simple; (iii) that it is the aim of science to present simple theories; (iv) that simplicity, like beauty, is a virtue worth having for its own sake; and (v) that simplicity is primarily a pragmatic virtue. Objections are raised either refuting or seriously weakening the first four claims. The fifth claim, the pragmatic one, is defended and illustrated by showing how James Clerk Maxwell employs simplicity pragmatically in his molecular theory of gases. It is also shown that, despite what Newton claims when he invokes epistemic simplicity in his argument for universal gravity, simplicity does no epistemic work for him. Despite what he claimed, his law was a speculation.