The Limits of Plato's Test

Aristotle is often taken to define priority in being in Metaphysics Delta.11, where he says that those things are prior in being which "admit of being without other things, while these others cannot be without them: a division which Plato used" (1019a3-4). But Aristotle's pattern of arguments about priority - some of which use Plato's Test and others of which use distinct, causal tests - looks puzzling if Plato's Test is his definition. This paper offers a new interpretation of Delta.11 on which it offers a guide to the Aristotelian use of Plato's Test, given that being is said in many ways, rather than endorsing it as Aristotle's own definition of priority. This reading illuminates Aristotle's pattern of arguments in the corpus - explaining why Aristotle uses Plato's Test in some cases and departs from it in others - and suggests a plausible story about how these arguments were shaped by engaging with Plato.