Thrasymachus is shown to be disgusted not only by the deference the interlocutors have been showing one another but also by the imminent conclusion of the Socrates–Polemarchus exchange that the t-just man helps everyone by making them better – that is, more l-just. The transition to Thrasymachus’ “political” characterization of justice as the “advantage of the stronger,” where “the stronger” is the ruler, is shown to be the natural extension of Polemarchus’ t-justice, transformed at the hand of Thrasymachus into the craft of ruling. Of the variety of labels scholars have affixed to Thrasymachus and to his position, it is determined that Thrasymachus is best described as a cynic and perhaps as an immoralist. It contends further that Thrasymachus’ view is consistent throughout. It locates the crux of the disagreement between Thrasymachus and Socrates in the clash between Thrasymachus’ notion that a ruler in the precise sense never makes, through error, laws that fail to further the ruler’s own advantage, and Socrates’ contention that, on the contrary, a ruler in the precise sense advances the welfare of the ruled, promoting the advantage not of the stronger but of the weaker.

In this chapter, I argue that, in light of his critique of rival theories of efficient causation, there is a puzzle latent in Aristotle’s own account. According to that critique, efficient causes must explain why their effects come about when they do rather than at some other time, a feature I call temporal contrastiveness. But it is not clear how the various elements of one of Aristotle’s preferred examples of such causation, the activity of experts, can enjoy this feature. Solving the puzzle yields a novel reading of Aristotle, one according to which expert skills genuinely change in the course of their exercise.

I begin by considering a condition Aristotle sets on action individuation: A difference in final cause entails a difference in actions. Next, I turn to Aristotle’s account of the teleological structure of expert activity. This kind of activity mirrors the classic case of Anscombe’s poisoner. But for Aristotle, the final causes in expert activity very finely, with the result that final causation is not transitive. So it turns out that Anscombe and Aristotle disagree about one of the most basic tenets of action theory: Anscombe individuates actions coarsely, Aristotle finely. In this regard, Aristotle is not her friend.

This introduction gives context for a detailed study of accidental causation. Accidental causation sits at the intersection of two strands of Aristotle’s thought: causation and accidentality. Accidental causation itself is not, however, well-understood. The introduction concludes with an overview of the rest of the volume.

I offer a new analysis of Aristotle’s concept of an accidental cause. Using passages from Metaphysics 5 and 6, as well as Physics 2, I argue that accidental causes are causally inert. After defending this reading against some objections, I draw some conclusions about Aristotle’s basic understanding of causation.

I present a new puzzle that concerns Aristotle’s accidents. This puzzle arises when applying a basic requirement of accidentality to the variety of cases Aristotle provides. In short, Aristotle seems to offer, now the thought that a is accidental to b, and now that b is accidental to a; but if accidentality is asymmetric, as it seems to be, then a’s being accidental to b implies that b is not accidental to a. One might offer a schooled Aristotelian solution, allowing that while a is in a sense accidental to b, b is accidental to a in a quite different sense. But, as I will argue, this solution does not work, for there are cases in which a and b are accidental to each other in the same sense. Ultimately, the solution to the new puzzle relies not on distinguishing between senses of ‘accident’ but rather on distinguishing between accidentality and accidental sameness.

Typically, Aristotle’s notion of an accidental unity is explained using our concept of identity, but doing so is fraught and liable to mislead. I argue that we should explain accidental unities in terms of sameness: Doing so not only shows a coherence among texts thought to be in tension with one another, it reconciles the two competing conceptions of accidental unities in a satisfying way. I conclude by answering several Boolean questions that naturally arise in response to the inclusion of accidental unities in Aristotle’s ontology.

I show that a consequence of Lear’s canonical analysis of ’qua’ is that the doctor’s causing a house qua housebuilder entails that the doctor is a cause of a house, but this fact is incompatible with Aristotle’s own thought. I proceed in two stages. First, I give Lear’s analysis and show that it has the consequence I say it has by applying the analysis to a passage from Physics 1.8. Second, I consider what follows from this passage on the basis of Aristotle’s account of causing as such and its connection to causing simply. I argue that, on Aristotle’s considered view, failing to cause simply is simply failing to cause. And it is because of this that he denies precisely what Lear attributes to him. The resulting picture shows that, in all likelihood, there is no analysis of Aristotle’s use of ‘qua’. This is so because the relation between F and G, when something is F qua G, is not one that can be captured in the language of necessary and sufficient conditions with modals. For Aristotle, being F qua G does not entail, as Lear would have it, that Gs are necessarily Fs; rather, it entails that Gs are naturally Fs.

I consider two claims about the texture of Aristotle’s natural world: first, that substances have indefinitely many accidents; second, that effects have indefinitely many accidental causes. Aristotle takes the first claim to explain the second, but the conceptual connections between them are not obvious. I show all that is required to connect one to the other, and in doing so work out the logic of accidental causation.

I begin by outlining the ontology of lucky occurrences. Based on the conditions that Aristotle sets on such occurrences, we see that their ontology is populated by accidental unities. Next, I argue that, based on the findings of earlier chapters, Aristotle takes lucky occurrences to be uncaused. I then consider what is sometimes taken to be evidence that lucky occurrences are, in fact, caused. I argue that, in each case, Aristotle’s claims only amount to its being as if something caused a lucky occurrence, which is consistent with there being no cause of such occurrences. I conclude by discussing the ramifications of this account for Aristotle’s physics. Though there is more to accidental causation than luck, the fact that lucky occurrences are uncaused entails that there are more varieties of accidental causation than is normally thought. Ultimately, the case of luck suggests that the standard model of accidental causation is to be expanded: Rather than analyzing accidental causation in terms of causation and accidentality, we should analyze it in terms of causation and sameness.

I show that both Aristotle’s ontology and his theory of causation are ordered hierarchies: Both entities and causes are divided into different groups, and those groups are ordered according to their relevant priority. I explain how the facts about these kinds of priorities fit together, arguing that certain accidental beings are causally prior without anything being causally prior to them. I conclude with an account of the resulting ontology and etiology. It turns out that the role of the accidental in Aristotle’s natural philosophy is orthogonal to its role in his ontology. The accidental stands to doing as the substantial stands to being.