I have said that the Ethics has the form of a search, and that a search has four distinguishable steps: formulating criteria for what is sought; identifying the field of search; examining that field; applying the criteria. Aristotle takes the first two steps in book 1. He sets down criteria which, he thinks, the ultimate goal of human life must satisfy, and he identifies in a general way his field of search, by arguing, as we have seen, that the ultimate goal of human life involves some “activity in accordance with virtue.” More precisely, he does both of these things in chapter 7, which is the pivotal chapter of the book. After book 1, he then conducts his search, by looking at the various virtues and their characteristic activities.

A word about terminology is in order. Aristotle refers to the ultimate goal of human life variously as: “the good”; “the human good”; “the practically attainable good”; “the best thing”; “the highest thing”; and “the ultimate (or ‘last’) good.” Clearly, he regards it as a kind of end point, and whether we imagine this as the end point of a vertical (“highest”), horizontal (“last”), or evaluative (“best”) sequence is irrelevant.

He also calls it eudaimonia (you-dye-mone-EE-ah) and says that people would agree in calling it this. “eudaimonia” was a popular term, not a technical term in philosophy, which meant literally to be blessed by a spirit or god (see 9.9.1169b7–8), or to be blessed as regards one's own spirit.

By the end of book 6 Aristotle has completed his examination of the virtues, both the virtues of the non-rational part of the soul that is responsive to reason (books 3–6) and those of the rational part of the soul (book 6). One would think that, at this point, he would be in a position to bring his investigation in the Ethics to an end. He had said (in book 1) that the ultimate goal of human life is some activity, or activities, of the sort that we can carry out through having the virtues. With a view to determining this, he identified and described the various virtues. Should he not now simply make a decision on this matter? Yet he does not attempt to do so until book 10, chapter 6.

For the moment, Aristotle puts on hold his search for happiness, in order to discuss three topics which he regards as closely related: pleasure, friendship, and akrasia. He discusses pleasure (7.11–14; 10.1–5), because he wishes to argue that happiness is the most pleasant as well as the best good. Friendship (books 8 and 9) is important, because relationships involving friendship are the ordinary context in which good persons exercise their virtue; moreover, since human beings are social animals, human happiness will be essentially social and therefore something that must be shared among friends, if possessed at all.

Let us recapitulate Aristotle's argument once more. He is looking to identify the ultimate goal of human life, which he conceives of as some activity, regularly repeated, which appropriately serves to organize everything else that we do, and which has the marks of Ultimacy, Self-Sufficiency, and Preferability. He argued in the Function Argument of book 1 that activity like that will be something that only a good human being can do, that is, it is activity that can be accomplished only by someone who has the “virtue” of a human being. Thus he turned in book 2 to an examination of human virtue.

But human virtue turns out to be complex; it admits of analysis; it has various “parts.” One such “part,” related to character, makes someone good at following or carrying out what he reasonably thinks he should do. It does this, Aristotle claimed, in two ways: by maintaining a person's motives in a condition of responsiveness falling between irrational and excessive extremes, and by assisting a person in crafting his action with refinement, so that it is appropriate as regards all of the various dimensions of an action. All stable conditions by which we become like this are particular character-related virtues, and Aristotle regards these as including courage, self-mastery, generosity, particular justice, and a handful of other good traits.

ARRIVING AT THE END

Perhaps the most puzzling sentence in the entire Ethics is one that Aristotle apparently thinks should be perfectly clear. It occurs at the beginning of 10.7, where he begins to give his final views on the ultimate goal of human life, happiness (eudaimonia): “If happiness is activity in accordance with virtue, it is reasonable that it be activity in accordance with the best virtue” (1177a12–13). This is puzzling, because Aristotle, as we have seen, has throughout the Ethics been deliberately maintaining a kind of indecision as regards what we have called Selection and Collection. Happiness is activity in accordance with virtue – granted – but is it some single such activity (Selection) or all such activities (Collection)? As late as 10.5 he was apparently keeping the question open: “So whether there is one sort of activity or several which are characteristic of a complete and blessedly happy man, the pleasures that bring these activities to completion would in the strict sense be referred to as ‘human pleasures’ ” (1176a26–28). If anything, that passage tips toward Collection, since it speaks of the pleasures that bring these activities to completion (in the plural). Yet in 10.7 the matter is suddenly settled.

The state of Aristotle's argument near the end of book 1 of the Ethics is as follows. There is an ultimate goal of human life, namely whatever is the aim of that expertise which is required in order reasonably to govern political society. We can be assured that there is such an aim, and such an expertise, Aristotle supposes, because political society is a natural form of association for human beings and therefore has a definite purpose or goal. We can identify three (or perhaps only two) criteria which such a goal must satisfy: it must have the marks of Ultimacy, Self-Sufficiency, and (perhaps also) greatest Preferability. We can also identify, roughly, the general sort of thing that this ultimate goal is going to be: as Aristotle maintains in the Function Argument, the ultimate goal of human life involves some activity which a human being can accomplish only through his having a trait that contributes toward someone's being a good human being. Such a trait is a “virtue,” so the ultimate goal of human life is some “activity in accordance with virtue.” We can determine the ultimate goal of human life, then, by looking at activities of that sort and seeing which of them satisfy the criteria of Ultimacy, Self-Sufficiency, and greatest Preferability.

THE BASIC STRUCTURE OF THE NICOMACHEAN ETHICS

The Nicomachean Ethics, Aristotle tells us, is a search or an investigation (1.6.1096a12; b35; 1102a13). It poses a question at the start, looks at various possible answers along the way, and concludes with a definite judgment. The treatise therefore has something of the shape of a detective story.

What Aristotle tells us he is looking for, and what he wants us to join with him in looking for, is what he calls the “ultimate goal” of human life. Informally, we might think of this as what counts as “doing well” in life, or what it is for someone to be in the true sense “a success.” To attain our ultimate goal is to achieve “happiness.” Practically speaking, the ultimate goal in life is something toward which we would do well to direct everything else that we do. We reasonably prefer this to anything else. Our ultimate goal, we might think, is something we can rest satisfied in: when we attain it, we require nothing more.

Is there such a goal which is the same for all, and, if so, what is it? This is the basic question of the Ethics.

It is useful to think of any search as involving four basic elements. Suppose, for instance, that a detective wished to establish the identity of a person who committed a murder.

Aristotle begins examining particular character-related virtues in 3.6. He looks first at courage, then self-mastery (or “moderation”), then generosity and magnificence, magnanimity and an unnamed virtue dealing with honor, before examining various minor social virtues. He reserves special treatment for the virtue of justice, which he considers a character-related virtue as well, but which he thinks is set apart in interesting ways from the others. I shall follow his practice and consider his treatment of justice separately, in the next chapter.

Let us review the argument once again. The reason why Aristotle wishes to examine the virtues, paying special attention to the sorts of actions a virtuous person does, is that he thinks that the ultimate goal of human life is some kind of action or activity that we can accomplish only through our having virtue. As was said, this goal should be understood as taking the form of an activity, repeated at intervals, which would rightly serve to organize and direct everything else that we do. But which activity of that sort should serve as our ultimate goal? It is that activity, Aristotle has argued, which satisfies the criteria of Ultimacy, Self-Sufficiency, and (perhaps) greatest Preferability. But we cannot determine which activity satisfies those criteria until we become clearer about the activities that are indeed distinctive of the various virtues. So this now is Aristotle's task, which he carries out in 3.6–6.13. He considers first character-related virtues, and then thinking-related virtues (in book 6).

UNPLEASANT DIFFICULTIES

What can be so common and so well known to us as pleasure? Do we not seek it throughout the day? Does it not frequently guide or even sway our actions? Many people apparently even live for pleasures of a certain sort.

And yet it seems almost impossible to say what pleasure is. Is it a sensation, like seeing a patch of blue sky? Or is it a feeling, like joy and delight? If it is feeling, can it be enduring, like a “mood,” or is pleasure something passing, more like an emotion? But perhaps pleasure is not a “thing” that we are related to at all, but rather our being related to something in a certain way, so that to be pleased simply is to “take pleasure” in something that is not itself a pleasure. Yet is it not also pleasant to take pleasure in something? (How could it not be?) But then, if it is pleasant to be pleased, a pleasure could serve as an object of pleasure.

Moreover, what is the relationship between pleasure and attraction? Might we be repelled by a pleasure, qua pleasure, or is that suggestion nonsense? But if we are necessarily attracted to a pleasure, must we not in some sense inevitably take it to be good? It would be, if a good is a goal. Or at least this much seems true: the fact that something is pleasant seems to be some kind of sign that it is good.

Let us review the argument to this point. In book 1 Aristotle argues that the ultimate goal of human life is some “activity in accordance with virtue,” and he sets down criteria that he thinks the ultimate goal must satisfy. In 1.13 and 2.1 he analyzes human virtue into thinking-related and character-related virtue, and in the remainder of book 2 he constructs a list, which he regards as exhaustive, of particular character-related virtues. One would think that his next step would be to examine these virtues individually. In fact he puts this off until 3.6. Instead, in 3.1–5 he undertakes a discussion of human action and the psychology underlying human action.

This is not a digression, as it might seem, because Aristotle's discussion of human action follows naturally from, and is even required by, various claims that he had put forward in book 2. Recall that, as Aristotle sees it, the discipline of ethics is practical: its aim is that we become good and live well. But, as he has just argued in book 2, we cannot become good unless we acquire the virtues of character. As we saw, Aristotle thinks that we generally acquire the virtues through being directed, by those in authority over us (by our parents when we are immature, and by legislators, even when we are mature citizens), to do actions characteristic of those virtues and to refrain from actions characteristic of the contrary vices.

I vividly remember my first encounter with Aristotle's Nicomachean Ethics in my first semester of college. I was assigned the text as part of an introductory course in the history of philosophy. My professor, Ed McCann, had said in lecture that it was widely accepted that Aristotle and Kant towered above all other philosophers, on account of their depth and comprehensiveness. So I had the highest expectations as I went off to the library, the text of the Nicomachean Ethics in hand, to grapple with Aristotle's thought.

But lulled perhaps by the soft hum of the heating system in the library, or by the plush comfort of the leather chair into which I had sunk, I simply could not stay awake while reading. I would read a chapter or two of the Ethics; then nod off to sleep; then wake up and read another chapter; and then fall asleep again; and so on. During my brief periods of wakefulness, it was my impression that I was following the argument, and that what Aristotle was saying was, after all, commonsensical – a very common first impression of the Ethics, as it turns out. And yet really I was hardly understanding the text. What was happening was that the seeming obviousness of Aristotle's claims allowed me to run my eyes over the text fairly quickly, and yet the density and concentration of the underlying argument, to the extent that I did grasp it, caused a kind of intellectual overload, from which I would then escape by falling asleep.

One of the most startling and distinctive aspects of Epicurean philosophy is the atomic motion known as the ‘swerve.’ The Epicureans are materialists, holding that the only things that exist per se are bodies and ‘void,’ which is just empty space. Bodies are simply conglomerations of atoms, which are uncuttable, extended bits of ‘full’ space flying through the void as a result of their weight, past motions, and collisions with other atoms. But the Epicurean poet Lucretius writes that if all atomic motion were the deterministic result of past motions and weight, we would not have the ‘free volition’ (libera voluntas) which allows each of us to move ourselves as we wish. Since we evidently do have the power to move ourselves as we wish, there must be a third, indeterministic cause of atomic motion, in addition to weight and past motions – a ‘swerving’ of the atoms to the side at uncertain times and places, which saves us from fate.

In part, this book is an attempt to discern the role the swerve plays in preserving human freedom. However, the swerve cannot be studied in isolation; it must be understood in the context of Epicurus' ethics, philosophy of mind, and metaphysics in general. So the subject of this book is Epicurus' overall theory of human freedom.

Most of what Epicurus and Lucretius say about our freedom is compatible with causal determinism. This should not surprise us. Epicurus is not concerned with the freedom required for genuine moral responsibility, but with securing a sort of freedom of action – a rational self‐rule that allows us to control our actions and shape our character, so that we can attain a tranquil life. This type of freedom is compatible with causal determinism. However, Epicurus was led, by a series of philosophical mistakes – understandable mistakes, but mistakes nonetheless – to posit an indeterministic atomic motion to help defuse a threat to our freedom. The swerve plays only the subsidiary role of defusing the fatalist implications of the Master Argument and similar arguments based on the universal applicability of the Principle of Bivalence. Despite the swerve's relative unimportance in Epicurus' own theory of freedom, it is this element of his theory that in the end has had the greatest philosophical impact.

If I am right that it would be anachronistic to saddle Epicurus with a libertarian response to the ‘traditional’ problem of the apparent incompatibility of determinism and the ‘ability to do otherwise’ necessary for genuine moral responsibility, this raises the following questions: how did the ‘traditional’ problem arise, who was the first person to put forward a libertarian response to this problem, and how was this transmitted into the western philosophical tradition? Also, what role did Epicurus' positing of the swerve play?

My argumentation thus far has been partly positive and partly negative. As far as how the swerve is supposed to help secure our freedom is concerned, it has been largely destructive: the swerve is not involved directly in the production of free action; it is not supposed to secure the agent as the archê of either his character or his actions; it is not needed to protect the emergent self from the threat of reductionism. Neither De rerum natura, nor supposed Aristotelian antecedents in the Nicomachean Ethics, nor On Nature 25 allow us to determine the role the swerve is supposed to play in protecting human freedom.

However, many important positive results about Epicurus' views on our freedom can be gleaned from these texts, as well as Epicurean ethics and psychology overall. Lucretius' discussion shows that libera voluntas is what allows us to act as we wish to act, and that it is a sort of intentional impulse. Somehow, if sequences of cause and effect stretched back infinitely in the past, we would not have this libera voluntas, and the swerve saves us from this. Insofar as Epicurus is picking up on Aristotelian antecedents in the Nicomachean Ethics, he would agree with Aristotle that it is crucial that an agent's character and actions have their origin in the agent himself.