Aristotle’s theory of human happiness in the Nicomachean Ethics explicitly depends on the claim that contemplation (theôria) is peculiar to human beings, whether it is our function or only part of it. But there is a notorious problem: Aristotle says that divine beings also contemplate. Various solutions have been proposed, but each has difficulties. Drawing on an analysis of what divine contemplation involves according to Aristotle, I identify an assumption common to all of these proposals and argue for rejecting it. This allows a straightforward solution to the problem and there is evidence that Aristotle would have adopted it.

Aristotle appears to claim at Nicomachean Ethics 10.8, 1178a9 that there are two kinds of happy life: one theoretical, one practical. This claim is notoriously problematic and does not follow from anything that Aristotle has said to that point. However, the apparent claim depends on supplying “happy” or “happiest” from the previous sentence, as is standard among translators and interpreters. I argue for an alternative supplement that commits Aristotle to a much less problematic and unexpected position and permits a wider variety of interpretations of Aristotle’s overall theory of happiness.

Diogenes of Apollonia subscribes to a principle that, roughly, causal interaction and change require a certain sort of uniformity among the relata. Attending to this principle can help us understand Diogenes’s relationship to the superficially similar Anaximenes without insisting, as some do, that Diogenes must be consciously responding to Parmenides. Diogenes is distinctive and philosophically interesting because his principle combines two senses of ‘archê’ (principle, starting-point), namely, the idea of source or origin and that of underlying (material) principle, and gives the rudiments of an argument for associating the two, by which Aristotle may have been influenced. Diogenes’s principle and its deployment in biological explanations thematized a concern that Aristotle at least partially shared, and which led him to appeal, as Diogenes is said to have done, to pneuma (breath, air).

Aristotle’s typical procedure is to identify something’s four causes. Intentional action has typically been treated as an exception: Most think that Aristotle has the standard causalist account, according to which an intentional action is a bodily movement efficiently caused by an attitude of the appropriate sort. I show that action is not an exception to Aristotle’s typical procedure: Aristotle gives the resources to specify four causes of action, and thus to articulate a powerful theory of action unlike any other on offer.