Aquinas’s Fifth Way is usually taken to be an adumbration of Paley-like design arguments. Paley-like design arguments have fallen on hard times over the past few centuries, and most contemporary defenders of design arguments in support of theism favor some version of the fine-tuning argument. But fine-tuning designarguments, like Paley’s design argument, are consistent with atomism. And all such arguments are vulnerable to the objection that, given a long enough stretch of time and a sufficient number of universes, there would be no need to posit a designer. In this paper we argue that a deep understanding of Aquinas’s Fifth Way depends upon understanding his hylomorphic account of the nature of composite substance, an account that is inconsistent with atomism. We argue that if one grants hylomorphism, Aquinas’s Fifth Way is difficult to resist. And we defend Aquinas’s hylomorphism against several common objections
