In his theory of time Aristotle does not often mention the present time and nowhere gives a detailed account of it. Nonetheless, present time plays an important role in his conception. I primarily argue for the following claims: (1) According to Aristotle there is a perception of motion and there is a perception of time. These combined perceptions can neither occur in the past nor in the future nor in an indivisible now. Thus, there must be a present time. (2) (...) Aristotle acknowledges the passage of time. This passage of time can only be understood as a passing present. And since an indivisible now cannot pass, the passage of time delivers a further argument for the basic assumption of a present time. – For the most part I simply follow Aristotle’s argument in Physics IV 10 and 11. In doing so, I distinguish present time and now in the introductory puzzles, investigate the passing present in the co-perception of change and time, discuss the relation between change and the passage of time as well as the relation between the passing present and the different nows. (shrink)

Ontological separation plays a key role in Aristotle’s metaphysical project: substances alone are ontologically χωριστόν. The standard view identifies Aristotelian ontological separation with ontological independence, so that ontological separation is a non-symmetric relation. I argue that there is strong textual evidence that Aristotle employs an asymmetric notion of separation in the Metaphysics—one that involves the dependence of other entities on the independent entity. I argue that this notion allows Aristotle to prevent the proliferation of substance-kinds and thus to secure the (...) unity of his metaphysical system. (shrink)