When philosophy teachers present the ‘-ism's’ pertinent to mind–body relations, and are still at the broad-brush stage, quite often one finds them pairing Plato and Descartes as the two most eminent dualists of our Western tradition. As Plato to the through-and-through materialist Democritus, so Descartes to Gassendi, it is often suggested – reasonably, perhaps. As the modern non-reductive materialist to his Cartesian bête noire, so Aristotle to Plato on soul–body relations, we are sometimes told – a misleading analogy, some think. For the purpose of contrast with various non-dualist views it may seem useful to group Plato's dualism and that of Descartes together, and in many contexts their differences may not matter. But if one simply compares the theories with each other, not with any third system, the differences are fascinating and seem important.

Of course there are similarities to sustain the initial pairing. Both philosophers argue that we consist of something incorporeal, whether one calls it ‘mind’ or ‘soul’, which for the time being is somehow united with a body that is part of the physical world. Both identify the self, the ‘I’, with the incorporeal member of this alliance. Both hold that my mind or soul will survive the demise of the body by means of which I set down these words for others by means of their bodies to access. Both may be understood as holding that the mind or soul can exist altogether independently of body, though Plato may have changed position on this point. Both are concerned with the immortality of the soul.

PART I

That the highest good is a severely abstract notion will not be disputed by anyone. If we find it a difficult idea to get hold of we might first want to blame the abstractness for our fumbling. But there is a less obvious source of difficulty, which I believe has not been discussed very much. It is that thinkers have wanted very different things from the idea. It has served many different functions in ethical theory. Yet historic battles over the identity of the highest good have often failed to make clear what was at stake. In Plato's Philebus, for example, a competition for the title is staged between Knowledge and Pleasure, but it is never explained what, if any, the winner's essential commitments would be. It seems not a waste of time to look at different interpretations of the theoretical role of the highest good. My inspection will be conceptual more than historical.

Let me start, however, with an historical point, one which has already been indicated. The question of the highest good comes to us from ancient Greek philosophy, and we encounter it there in the context of rival identity claims. This fact, while utterly familiar, is something to pause over – for two reasons. First, this context, the context of rival claims as to what is to count as the highest good, definitely colours and might even be said partly to characterise the problematic of the highest good; and this may strike us as a bit remarkable if we make comparison with other problematics involving unique objects.

There is a more pressing difficulty for determinism than the celebrated one to do with ascribing moral responsibility. It arises because we assume that events and actions usually make a difference to the world where they take place, and that we, at least in the short term, can often tell what the differences are. This double assumption, partly about the effects of actions and events, partly about our knowledge of them, seems threatened by determinism. I shall say presently why, but first a word on the greater urgency of this difficulty by comparison with the other, and more extensively discussed, problem to do with moral responsibility.

Moral responsibility presupposes agency, and agents act to make a difference, whether to themselves, to their environment, or to others. Perhaps there are cases where we reasonably hold someone responsible although her action, and even her choice of action, made no difference since the relevant effect was going to come about anyway independently. But I think such cases are possible only if the agent acts without realising that things are set up in such a way that her action makes the relevant effect not even the slightest bit more likely than it would have been without it. One cannot act with the purpose of making some desired thing happen if one is assured that acting so would be completely ineffectual in that respect. We may, in such a case, welcome the occurrence of what was willy-nilly going to happen.

Although much attention has been given in recent years to the topic of backwards causation, little if any has been paid to the concept of temporal continuing, which I hope to show is not only relevant to that topic but decisive for its concludings. Michael Dummett, indeed, in his fascinating 1954 paper showed himself aware that ‘backwards causation’ must square itself with temporal continuing. But little more seems to have been added since then. In this paper I shall argue that the temporal direction of causation is determined by the temporal direction of the continuing of events, and that as long as this is not clear, the argument for backwards causation looks sounder than it otherwise would. If my argument holds, it will follow that should there be no such concept as ‘backwards continuing’, neither will there be such a concept as ‘backwards causation’.

The argument requires us to examine the relation between the temporal direction of continuing and the temporal direction of causation. I shall begin by comparing backwards causation with forwards causation in order to find whether there is something absent in the former and present in the latter that we can identify as what makes forwards causation the viable concept it appears to be and whose absence in backwards causation correspondingly denudes it of meaning. I shall argue that even forwards causation would not make sense as causation at all if the events it relates were not taken as continuing in time; and that it is just this that is missing from backwards causation as philosophers have generally represented it.

I chose ‘leisure’ as the theme for this occasion partly because it's a topic which everyone – anyway, everyone present this afternoon – knows quite a lot about informally from their own experience. I chose it also because philosophy is supposed to be concerned with, among other things, human life and human nature in general, and reflecting about leisure is largely a matter of reflecting about its place in human life as a whole. It is not easy to say what is essential to human beings, because the attributes that seem deeply characteristic of us form such a long list, whereas stating the essence of something is traditionally supposed to be a matter of giving a single pithy fundamental formula. If, however, one is allowed to point to the essential by simply listing typifying characteristics, then the capacity to appreciate leisure and distinguish it from non-leisure must surely count as essential to human beings.

This is not to claim, of course, that the concept of leisure is universal to all cultures, nor that if a certain culture lacked this notion it might not all the same get along as well on the whole as we do, who have it. For conceivably that culture might recognise and realise some equally important human capacity whose object figures not at all in our own reflections and deliberate arrangements. We can be quite liberal in forming our list of essentially human capacities as long as we allow that there may be whole peoples, and long stretches of history, in which one or another essentially human capacity goes systematically unrecognised and largely or completely unrealised.

THE MAIN QUESTION

‘Which among humanly practicable goods is the summum bonum or highest good?’ is the first and central question of Aristotelian ethics. As we might expect, Aristotle's answer is rather abstract. Even so, he intends it to be informative and to provide guidance for policy-making and action. The present essay will focus on the account put forward in the Nicomachean Ethics, Book I, chapter 7, where Aristotle equates the highest human good with ‘the rational soul's activity of virtue in a complete life’. This compact formula sets an agenda that will explicate the highest good through detailed studies of (a) the virtues, and (b) the two most philosophically controversial components of a complete life, namely friendship and pleasure. Fully spelled out, the compact formula yields a conceptually rich, and substantial, ideal.

This essay will take the compact formula as given, and will not comment on the reasoning by which Aristotle arrives at it. Nor is it my present purpose to look closely at any portion of the content of his ideal. The main question addressed here is a formal one: what does it mean in the context of Aristotelian ethics to regard X as the highest good, whatever X may be? In discussing this question, we shall be led to consider the chief components of Aristotle's ideal to see how their interrelation constitutes a whole that fits the formal account of the highest good.

PERSPECTIVES ON PRACTICALITY

The claim that X is the highest good seems to imply that X is the good that we should strive above all to realise. But is that what the claim means?

INTRODUCTION

I begin with the ancient Stoics, end with the Aristotelians, and in between shall draw together some thoughts not ascribed to anyone in particular.

The Stoics were universal determinists. That is, they held that whatever takes place is and always has been inevitable or necessary, given its antecedent causes. This doctrine provoked one of the catchier bits of ancient reasoning, the Lazy Argument. Paraphrased for the modern ear, it goes: for any event E, (1) if the world is such that it is inevitable that E will occur, then E will occur no matter what else happens; and if the world is such that it is inevitable that E will not occur, then E will not occur no matter what else happens; but (2) (according to Stoic determinism) either the world is disposed in one of those two ways or it is disposed in the other. So (3) either way, the outcome will be whatever it will be no matter what else happens. Consequently, even if the occurrence of E is preferable to its non-occurrence or vice versa, nothing that anyone does with a view to producing the one or blocking the other can make the slightest difference. For example, if you, a sick person, are going to recover from your illness, then you will recover regardless of whether you get medical help. If, on the other hand, you are going to die from your illness, then you will die from it whether or not you get medical help.

Having traced mind's essence, operation, and objects, Aristotle needs to give more attention to thinking's initiation. Possession of knowledge puts universals in the soul that provide for thinking at wish. But what can provoke such wish, and in general how does dispositional knowledge lead to actual thinking? This is the role of phantasmata. This has been hinted at previously (see 403a8–10, 427b16, and perhaps 430a24–25), but he now needs to offer fuller consideration. He should not merely resort to phantasmata as a desperate assumption but argue for their role in thinking. In this chapter Aristotle begins with an obvious case, practical thinking and its initiation by phantasia, and then goes on to other types of intellect. His guide is the way sense perception of the pleasant or painful causes desire and pursuit or avoidance. As sense has desire and motion concatenated with it, so practical thinking has phantasmata, desire, and action linking with it. He then expands upon this case by further comparison of mind with sense. If sense is a unity, because (1) the action on the medium affects the sense and causes desire and pursuit or avoidance and (2) the five senses lead to a central sense and thus are subfaculties of the sense faculty, mind also is a unity requiring phantasmata along with its thinking and the mind is composed of subfaculties for practical thinking, theoretical thinking, and mathematical thinking. What applies to practical thinking will apply analogously to these other sorts of thinking.

Having sketched the views of the predecessors and why they hold them, Aristotle criticizes them for the rest of book 1. This is Aristotle's version of Socratic cross-examination. Chapters 3 and 4 challenge the views of those explaining the soul as mover in motion; chapter 5 attacks those focusing upon the soul's role in cognition. Cognition enters chapter 3 to some extent as well, because cognition may be a sort of motion. The soul might be in motion either because as mover of the animal it has motion of its own that originates motion in the body or because cognition is some sort of motion. This prominence of motion helps explain why 405b31 announces that soul's involvement with motion should be considered first (cf. 403b27–29). All the criticism of predecessors will be dialectical. Aristotle cannot simply demonstrably refute the endoxa but only argue against them on the basis of other endoxa. Dialectic lacks firm starting points, instead using some endoxa to challenge others. Yet in spite of being dialectical, Aristotle's arguments end up with the definitive conclusion that the predecessors' positions are impossible (see, e.g., 405b31–406a3). How can such a solid conclusion emerge from dialectical consideration?

Aristotle, it will be seen, uses a barrage of arguments. It may well provoke suspicion that so many arguments enter the attack against his predecessors' views. Were there a decisive argument, we might expect it to suffice, but Aristotle frequently resorts to a series of arguments. Plato's Socrates occasionally does much the same himself.

Exploring the purpose of Socratic questioning in the dialogues is a crucial part of making sense of Plato's approach to philosophical and sophistical rhetoric. Superficially, Socratic questioning seems to share something in common with sophistic eristic. Socrates often asks questions that seem to lead his opponents toward conclusions that do not necessarily follow from the premises. Perhaps Adeimantus puts it best when he speaks to Socrates about this common perception of philosophers in the Republic:

Here, Adeimantus suggests that the experience of being questioned by Socrates feels akin to being tricked in a game of checkers. This image of a game particularly emphasizes the possibility that Socrates is interested in being the victor in a competition rather than in seeking the truth.

This book explores how Plato separates the philosopher from the sophist through the dramatic opposition of Socrates to rhetoricians and sophists. In one way, its thesis is simple. Plato distinguishes Socrates from the sophists by differences in character and moral intention. In the broadest terms, Plato might agree with Aristotle's claim in the Rhetoric that what defines a sophist is “not his faculty, but his moral purpose” (1355b 17–18). In another way, the problem is difficult, for the philosopher and the sophist share many characteristics in how they speak and act; these similarities are not superficial but go to the very heart of what Plato presents as philosophy, sophistry, and rhetoric. The tendency of contemporary scholarship has been to emphasize the distinctiveness of Socratic or Platonic philosophy in terms of a technical method separable from rhetoric. One reason for this assumption is that Socrates seems to point toward the possibility of such a method in the Gorgias in his contrast between the political art and merely imitative rhetoric (Gorgias 464b–466a). However, when one turns to other dialogues, the relationship among philosophy, rhetoric, and sophistry becomes murkier. The Phaedrus seems to show philosophy and rhetoric as compatible, while Book One of the Republic presents a sophist with an intellectual position about justice alongside Socrates, with arguments that can seem sophistical. Plato's Sophist defines the sophist but, at one point in the dialogue, the Stranger equates “noble sophistry” with a practice that sounds much like Socrates' questioning activity (Sophist 230b–c).

Two main tasks remain to complete in the treatment of soul. Near the beginning of the De anima it was announced that the investigation of soul is to disclose its nature and essence along with its accidents (402a7–8). These accidents are especially the operations of living things: nourishing themselves, perceiving, walking, swimming, flying, thinking, and so on. Presumably these somehow have to be demonstrated as following from the accounts of the soul and its capacities (see 402b16–403a2). Moreover, in book 2 in 413b9–10, 413b33–414a1, and 414b33–415a1 Aristotle announced that additional discussion is forthcoming about why the soul has certain capacities in succession. Why does nutritive capacity have priority over all other capacities of soul, and similarly all the other capacities presuppose the capacity for sense perception, while touch is the most fundamental sense? Now the anticipated treatment appears in confirmation of his whole approach to the soul and the soul's relation to body. If certain faculties of soul are necessary in succession, then their operations, the main accidents of the soul, are demonstrated as necessary. Achievement of this demonstration supports the definitions upon which it is based.

The argumentation here is teleological and hypothetical; that is, certain parts must be present if certain functions are to be performed and natural ends to be attained. The ends at issue are life and the good life that entered into the very definition of soul in ii i.

Having completed his general account of the nature of mind and the way this makes thinking possible, Aristotle considers in some detail the basic objects of thought: those about which we think truly as the special sensibles are those perceived truly. His treatment of intellect further resembles the inquiry into sense perception, since, after treating the nature of sense in ii 5, he discusses the various sensible objects in some detail in ii 6, and now after dealing with mind in iii 4–5, he takes up the objects of thought in iii 6. As in ii 5 there is some preliminary consideration of the sensible objects (see 417b19–28), so in iii 4.429b10–22 there is brief attention to the objects of intellection, though the fuller treatment occurs here in iii 6. Also the way thought draws its objects together as one will receive attention in iii 6, somewhat comparable to sense's drawing things together as he discusses in iii 2. Aristotle has been speaking rather as if all knowledge were the theoretical knowledge of essences. Thought may be about these primarily, but it also extends to more objects. Presumably he supposes all thinking explicable, much as all sense-perceiving, if he can account for its most basic kinds and objects. In addition, by showing the possible breadth of thought, he begins to justify his initial assumption from iii 4 that thought can think all things.

The first part of chapter 5 completes the examination of the self-moving number theory of soul. In words reminiscent of 408b32–409a1, Aristotle announces:

We are getting the result of the previous examination of soul as a number that moves itself. “Just as we said,” appearing prior to any indication of what has been said, can refer to the places in which Aristotle has spoken of fine-grained body (λεπτομερής), that is, 405a5–7 and a21–22, or to the passage in which the units in the self-moving number were likened to small corpuscles (409a10–11), or to Democritus's way of having soul as mover of body (406b15–22 and 409a11–15), or to the passage opening the reflection on the self-moving number conception (408b32–409a1), or, perhaps most likely, to the whole previous discussion of self-moving number (408b32–409a30). Resembling many of the thinkers who sought for soul the subtlest and most fine-grained body, the self-moving number view has soul as number composed of units. Aristotle has compared these units to points and even tiny corpuscles, as if Democritus reduced his soul atoms to points (see 409a10–12).