"That which is proper to each thing is by nature the best and the most pleasant for it. For man this the life according to intellect (νοῦν), if the intellect more than anything else is man. This life therefore is also the happiest (εὐδαιμονέστατος). Happiest secondarily is the life according to the other virtue (δευτέρως δ᾽ ὁ κατὰ τὴν ἄλλην ἀρετήν). For the activities in accordance with this are human (αἱ γὰρ κατὰ ταύτην ἐνέργειαι ἀνθρωπικαί). We display justice, courage and the other virtues in our intercourse with our fellows..." (Nicomachean Ethics X.8.1178a5-8).

The life "happiest secondarily" is the life in which one has "practical wisdom" (φρόνησις). What is this life?

(It is traditional in this context to translate φρόνησις as 'practical wisdom.' This Greek word derives from from φρήν. In Homer, the shades of the dead don't have φρήν. They flit about. They are ἄφρων ("without sense"). Their behavior is crazed and frantic. The presence of φρήν gives one the ability to think and have understanding and thus to act sensibly.)

The life of practical wisdom is a life of reason in the form of "choice" (προαίρεσις). Choice is the origin of movement proper to human beings, but it is not a matter of reason without qualification. "Choice is intellect (νοῦς) combined with desire or desire combined with thought (διανοητική), and what originates in this way is man" (Nicomachean Ethics VI.2.1139b).

To understand Aristotle's view, it is helpful to begin with his conception of how movement originates in animals.

Purposeful Behavior in Animals

Aristotle thought that nonhuman animals lack reason but that some are "sensible" (φρόνιμα).

He thought that these animals are capable of controlling their behavior in ways that benefit them. For example, in the History of Animals IX.5.611, he reports that deer give birth alongside the road where predators are afraid to approach because of the likely presence of human beings. It can seem natural to think that in this way the deer are reasoning, but this is not Aristotle's view. He thought that the cognition in non-human animals that underlies this purposeful behavior is not a matter of "reason" (λόγος) and "reasoning" (λογισμός).

"In the other animals choice (προαίρεσις) does not exist, nor in man at every age or condition; for neither is deliberating (βουλεύσασθαι) and judgment about the why (ὑπόληψις τοῦ διὰ τί). It is possible that many have an opinion (δοξάσαι) whether a thing is to be done, but not through reasoning (λογισμοῦ). For that part of the soul is deliberative which contemplates (θεωρητικὸν) a certain cause. For the 'for the sake of which' is one of the causes (ἡ γὰρ οὗ ἕνεκα μία τῶν αἰτιῶν ἐστίν)..., and that for the sake of which something is or comes to be, that we say is a cause, so the fetching of things is the cause of walking, if he is walking for the sake of this. Hence, those who do not have an aim [as a cause] are not deliberative" (Eudemian Ethics II.10.1226b).

"It is apparent that these two produce movement, desire (ὄρεξις) or intellect (νοῦς), if we set down that imagination (φαντασίαν) as a kind of intellect; for many follow their imaginations against their knowledge (ἐπιστήμην), and in the other animals intellect and reasoning do not exist (οὐ νόησις οὐδὲ λογισμὸς ἔστιν), although imagination does. So both can produce movement in respect of place, intellect and desire, but intellect in which there is reasoning for the sake of something is practical (πρακτικός); and it differs from the theoretical (θεωρητικοῦ) in respect of the end. Every desire too is for the sake of something; for the object of desire is the starting-point for practical intellect (πρακτικοῦ νοῦ), and the final step is the starting-point for action" (On the Soul III.10.433a9-17).

How, according to Aristotle, does purposeful behavior occur in animals if they lack reason?

Aristotle thought that a defining feature of animals is the capacity for perception and that perception implies the capacity for desire. Animals need to behave in certain ways in certain circumstances if they are to survive. Perception is the way they become aware of their particular circumstances, and desire moves them to engage in the appropriate behavior in these circumstances.

"If a living thing has the capacity for perception, it has the capacity for desire. For desire (ὄρεξις) comprises appetite (ἐπιθυμία), spirit (θυμὸς), and wish (βούλησις). All animals have at least one of the senses, touch. Where there is perception, there is pleasure and pain ..., and where there are these, there is appetite: for this is desire for what is pleasant" (On the Soul II.3.414b1-6).

Three Forms of Purposeful Behavior in Animals

1. In some animals, there are only perceptions tied to desires tied to behaviors.

In the History of Animals V.16.548b10-16, Aristotle reports that it is thought that sponges are animals and that they have a capacity for perception only in the form of touch. Touch in them is a stimulus for a certain behavior. A sponge controls its behavior in one way: it contracts when it is touched. It doesn't like being touched. It finds being touched painful, and when it is touched, it flees in the only way open to it. This behavior is supposed to be conducive to the sponge's survival because it helps prevent it from being dislodged from the place it is attached.

2. In other animals, the possible forms of behavior are much more complicated.

In the Nicomachean Ethics III.10, Aristotle says that hounds take pleasure not in scenting hares but in eating them and that the scent merely makes them aware of the hare. Aristotle does not provide the details, but he may have in mind a sequence like the following. If the hound has the desire to eat the hare, it must represent the state of affairs that is the object of this desire. Perception alone is not enough to account for this representation. Perception allows the hound to perceive the current state of its environment, but it needs to be able to envisage the prospective state of affairs of eating the hare. It is in terms of "imagination" (φαντασία) that the hound represents this prospective states of affairs. It has eaten a hare in the past and remembers this state of affairs as pleasant. Because it is hungry, the scent of the hare triggers an image in the hound of itself eating a hare. This image functions as the desire whose object is the state of affairs of the hound eating the hare. The hound needs to act so as to achieve the goal. Unlike the sponge, the hound can act in many different ways. So it needs something like a plan so that its actions result in it catching and eating the hare. It is in terms of "imagination" (φαντασία) that the hound forms the plan. It has chased down hares and eaten them in the past, and the hound remembers this sequence of events. The desire to eat the hare triggers in the hound an image of itself chasing down the hare. This image moves the hound to chase down the hare and to eat it.

3. In some animals, there is the cognition Aristotle calls "experience" (ἐμπειρία).

These animals who have acquired "experience" (ἐμπειρία) are better at discriminating among things in their environment in ways that benefit themselves. Aristotle illustrates the point with an example involving a medical practitioner who is more successful than the layman in treating certain diseases. It is clear, however, that he thinks that this cognitive ability, although less developed, is also present in some non-human animals. Consider, for example, an older dog who has chased down many hares over a long period of time. This dog may have gained "experience" (ἐμπειρία) with respect to the scent of the hare and its hiding place. This would allow the older dog to react to the scent in a more nuanced way and thus make it a more successful hunter.

"Animals are by nature born with perception (αἴσθησιν), and from this some come to have memory (μνήμη), whereas others do not. The former are more sensible (φρονιμώτερα) and capable of learning than those which cannot remember. ... The other animals live by impressions (φαντασίαις) and memories, and have but a [comparatively] small share of experience (ἐμπειρίας), but the human race lives also by art and reasoning (τέχνῃ καὶ λογισμοῖς). It is from memory that men acquire experience" Metaphysics I.1.980a).

The Origin of Movement Proper to Human Beings

As Aristotle says in the Metaphysics, "the human race lives also by ... reasoning (λογισμοῖς)." This is way of living is proper to human beings.

In human beings, some but not all desires belong to reason. The desire that belongs to reason is "wish." The other are "spirit" and "appetite." "Wish (βούλησις) is found in the reasoning part (λογιστικῷ) and appetite and spirit in the the part without reason (ἐν τῷ ἀλόγῳ ἡ ἐπιθυμία καὶ ὁ θυμός)" (On the Soul III.9. 432b5-6).

When a human being acts in a way that stems from "choice" (προαίρεσις) his motivation is a form of "wish" (βούλησις). Wish is a desire for what one believes is good in the circumstances. "Deliberation" (βούλευσις) is thinking about what to do to bring about this wished for end. So "choice" (προαίρεσις) for Aristotle is a form of the desire that stems from reason.

"Choice will be a deliberate desire of things in our power; for when we judge from deliberation, our desire is according to our wish (ἡ προαίρεσις ἂν εἴη βουλευτικὴ ὄρεξις τῶν ἐφ᾽ ἡμῖν: ἐκ τοῦ βουλεύσασθαι γὰρ κρίναντες ὀρεγόμεθα κατὰ τὴν βούλευσιν)" (Nicomachean Ethics III.3.1113a10-12). "Choice is not a wish (βούλησίς), though they appear closely akin. .... We wish for ends, but choose the means to our end; for example we wish to be healthy, but choose things to make us healthy.... In general, choice is concerned with things that are up to us (ἐφ᾽ ἡμῖν)" (Nicomachean Ethics III.2.1111b19-30). "It is preceded by consideration (προβεβουλευμένον), since choice involves reasoning and some process of thought (προαίρεσις μετὰ λόγου καὶ διανοίας)" (Nicomachean Ethics.III.2.1112a15-16). We deliberate about things that are up to us and practical (βουλευόμεθα δὲ περὶ τῶν ἐφ᾽ ἡμῖν καὶ πρακτῶν)" (Nicomachean Ethics III.3.1112a30-33).

Choices are "voluntary" because they stem from a wish, but the use of the word 'voluntary' can be misleading here.

The Latin noun voluntas is from the verb volo, which means "I wish." This is why βούλησις is translated as "wish" in Aristotle's discussions of the desire that belongs to reason, but Aristotle did not think that everything a human being does of his own accord is motivated by wish. A human being can, of his own accord, do something because he is motivated by the desires of "appetite" and "spirit." (This ancient understanding of what it is for an action to be "voluntary" shows itself in modern philosophical discussions. So, for example, in the "Tue Dec 16, 2014" entry in the Stanford Encyclopedia of Philosophy for "Voluntary Euthanasia," the author offers the following analysis of instances of "non-voluntary" euthanasia: "[t]here will be occasion to mention non-voluntary euthanasia — instances of euthanasia where a person is either not competent, or unable, at the time to express a wish about euthanasia and has not previously expressed a wish for it....")

"What comes about by force or because of ignorance seems to be ἀκούσια. What is forced has an external origin, the sort of origin in which the agent or victim contributes nothing--if, e.g., a wind or human beings who control him were to carry him off" (Nicomachean Ethics III.1.1109b35-1110a1). "What is ἑκούσιον seems to be what has its origin in the agent himself when he knows the particulars that the action consists in" (Nicomachean Ethics III.2.1110a22-24). "Choice (προαίρεσις) is something someone does of his own accord (ἑκούσιον). But they are not the same, the latter being the wider. Children and animals as well as men are capable of doing something of their own accord (ἑκουσίου), but they are not capable of choice" (Nicomachean Ethics III.2.1111b6-9).

An irrational form of purposeful behavior

On the relation between belief and desire, Aristotle follows Plato against Socrates. Plato and Aristotle think that not all desires stem from reason and that these desires can interfere with reason. For example, someone might have developed a habit of eating sweet foods. In a given circumstance, he might know that a certain food is the right one to eat but instead act on the basis of his desire for sweet food. To explain how this happens, Aristotle suggests that these desires interfere with reason and temporarily render the knowledge ineffective.

"The continent is the one who abides by his rational calculation (λογισμῷ), and the incontinent is one who abandons it. The incontinent person knows that his actions are base, but does them because of his feeling (πάθος), while the continent person knows that his appetites are base, but because of reason (λόγον) does not follow them" (Nicomachean Ethics VII.1.1145b10-14).

"We speak of knowing (ἐπίστασθαι) in two ways, and ascribe it both to someone who has it without using it and to someone who has and is using it. Hence it will matter whether someone has the knowledge that his action is wrong, without attending to his knowledge, or both has it and attends to it. For this second case seems extraordinary (δεινόν), but wrong action when he does not attend to his knowledge does not seem so" (Nicomachean Ethics VII.3.1146b31-36). "Some people, for example, those asleep or mad or drunk, both have knowledge in a way and do not have it. Moreover, this is the condition of those with passions (πάθεσιν). For anger and sexual appetite and some conditions of this sort disturb the body, and even produce fits of madness in some people. It is clear that we should say that incontinents (ἀκρατεῖς) have knowledge in a way similar to these people" (Nicomachean Ethics VII.3.1147a13-18).

"Spirit (θυμὸς) ... is like over-hasty servants who run out before they have heard all their instructions, and them carry them out wrongly, or dogs who bark at any noise at all, before investigating to see if it is a friend. In the same way, spirit, because the heat and swiftness of its nature, hears but does not the hear the instruction, and rushes off to exact penalty. For reason (λόγος) or imagination (φαντασία) has shown that we are being slighted or wantonly insulted, and spirit, as though it had inferred (ὥσπερ συλλογισάμενος) that is right to fight this sort of thing, is irritated at once. Appetite (ἐπιθυμία), however, only needs reason or perception (αἴσθησις) to say that this is pleasant, and it rushes off for gratification" (Nicomachean Ethics VII.6.1149a25-1149b1).

The Virtues of Character

A human being can makes choices well or badly. The virtues of character are necessary for making choices well.

In someone with the virtues of character, the part of his soul that does not have reason (but is capable of "listening to" and "obeying" reason) has developed dispositions to act in appropriate ways in the circumstances. A human being who is brave, for example, is disposed to act in appropriate ways with respect to frightening situations. He is not overcome by fear or excessive confidence, and he does what is appropriate in the situation. "Whoever stands firm against the right things and fears the right things, for the right end, in the right way, at the right time, and is correspondingly confident, is brave. The actions and feelings of a brave human being reflect what something is worth and what reason prescribes" (Nicomachean Ethics III.7.1115b17-19). He recognizes that the situation is frightening, but he nevertheless has appropriate nonrational desires ("appetite" and "spirit") and acts in appropriate ways to achieve the objects of these desires.

Human beings acquire the virtues of character by taking the actions that the virtuous would take in the situation. This behavior is a kind of practice. It trains the part of the soul that "listens to" and "obeys" reason (the part with "appetite" and "spirit") so that its desires are for the appropriate behavior in the circumstances.

"The nutritive part shares in reason (λόγου) not at all, the part with appetites (ἐπιθυμητικὸν) and generally desire (ὀρεκτικὸν) shares in reason in a way, in so far as it listens to and obeys reason. It listens in the way we are said to listen to reason from father or friends, not in the way we give reason in mathematics. The part without reason (ἄλογον) also obeys and is persuaded in some way by reason, as is shown by chastening, and by every sort of reproof and exhortation. ... [The part with reason has] two parts, one has authority in itself, and the other that has it by listening to reason as to a father. The distinction between virtues also reflects this difference. We say that some virtues are virtues of thought (διανοητικὰς) and that others are virtues of character (ἠθικάς). Wisdom (σοφίαν), quick comprehension, and practical wisdom (φρόνησιν) are virtues of thought. Generosity and temperance are virtues of character" (Nicomachean Ethics I.13.1102b29-1103a7).

"Virtue (ἀρετῆς), then, is of two sorts, virtue of thought and virtue of character. Virtue of thought arises and grows mostly from teaching... Virtue of character results from habit (ἔθους)" (Nicomachean Ethics II.1.1103a14-18). "A state of character arises from the repetition of similar activities. Hence we must display the right activities, since differences in these imply corresponding differences in the states. It is not unimportant, then, to acquire one sort of habit or another, right from our youth; rather, it is very important, indeed all-important" (Nicomachean Ethics II.1.1103b21-25).

The Life of Practical Wisdom

A human being who has "practical wisdom" (φρόνησις) has the virtues of character. He wishes for the right things in the circumstances, deliberates correctly about how to bring about these wished for ends, and has the part of his soul that obeys reason under control so that he acts in accordance with reason.

Plato thought that the soul is reason and that it exists both before and after its time in the body. In this way, the soul has two sets of concerns and interests. Its own concern is to exist in "contemplation" (θεωρία), but because it is temporarily in the body, it has to take on the practical problems associated with the body. In facing this problem, the soul should not forget its concerns but should take control of the body and makes it life in the body like the existence it enjoyed in "contemplation" (θεωρία) when it was outside the body.

Aristotle does not have this Platonic understanding of the soul and its relation to the body, but his view of reason is similar. He thinks that reason focuses on two kinds of matters. That which can be otherwise is the focus of the part of the soul with reason that Aristotle calls the λογιστικόν. This part of the soul figures out how to bring about the good.

"We said before that there are two parts of the soul, one with reason (λόγον) and one without reason (ἄλογον). Now we should divide in the same way the part with reason. Let us assume it has two parts, one with which we consider (θεωροῦμεν) beings whose origins do not admit of being otherwise, and one with which we consider beings whose origin do admit of being otherwise. For when the beings are of different kinds, the parts of the soul naturally suited to each are also of different kinds, since the parts possess awareness (γνῶσις) by being somehow similar and appropriate to their objects. Let us call one the part for knowledge (ἐπιστημονικὸν), and the other the part for reasoning (λογιστικόν), since deliberating (βουλεύεσθαι) is the same as reasoning, and no one deliberates about what cannot be otherwise. ... Hence we should find the best state of each part, for this is the virtue (ἀρετὴ) of each" (Nicomachean Ethics V1.2.1139a).

"[Practical wisdom (φρόνησιν)] is a state of reason (λόγου) attaining truth in relation to things that are good and bad for human beings" (Nicomachean Ethics VI.5.1140b5-6). "Of the two parts of the soul that have reason (λόγον), practical wisdom (φρόνησις) is a virtue of one of them, of the part that has belief (δοξαστικοῦ); for belief is concerned, as practical wisdom is, with what admits of being otherwise" (Nicomachean Ethics VI.5.1140b25-28). "It is not possible to be ... practically wise (φρόνιμον) without virtue of character (ἠθικῆς ἀρετῆς)" (Nicomachean Ethics VI.13.1144b31-32). Someone is not practically wise (φρόνιμος) simply by knowing (εἰδέναι); he must also act on his knowledge" (Nicomachean Ethics 1152a8-9).

The Life of Practical Wisdom is Happiest Secondarily

Why is the life of someone with practical wisdom secondary in happiness to the life of "contemplation" (θεωρία)?

The answer, it seems, is that the exercise of reason in practical wisdom is a less pure exercise of "intellect" (νοῦς) and "thinking" (νοεῖν) and so is less proper and hence is less pleasant.

"That which is proper to each thing is by nature the best and the most pleasant for it (τὸ γὰρ οἰκεῖον ἑκάστῳ τῇ φύσει κράτιστον καὶ ἥδιστόν ἐστιν ἑκάστῳ). For man this the life according to intellect (νοῦν), if the intellect more than anything else is man. This life therefore is also the happiest (εὐδαιμονέστατος)" (Nicomachean Ethics X.8.1178a).

Why is the exercise of reason in practical wisdom is a less pure exercise of "intellect" (νοῦς) and "thinking" (νοεῖν)? The answer is not very clear, but the suggestion seems to be that this exercise of reason involves desire and awareness of particulars whereas "intellect" (νοῦς) and "thinking" (νοεῖν) strictly is about universals only.

"Practical wisdom (φρόνησις) is not about universals (καθόλου) only. It must also come to know particulars, since it is concerned with action and action is about particulars. Hence in other areas also some people who lack knowledge but have experience (ἔμπειροι) are better in action than others who have knowledge. For someone who knows that light meats are digestble and healthy, but not which sort of meats are light, will not produce health; the one who knows that bird meats are healthy will be better a producing health" (Nicomachean Ethics VI.7.1141b14-21).

"Practically wise (φρόνιμος) young people do not seem to exist. The reason is that practical wisdom is concerned with particulars, and this comes to be known from experience (ἐμπειρίας), but a young person lacks experience, since some length of time is needed to produce it" (Nicomachean Ethics VI.8.1142a14-16).

Perseus Digital Library: Aristotle, Nicomachean Ethics, Eudemian Ethics
Henry George Liddell, Robert Scott, A Greek-English Lexicon: ἀεκούσιος, ἑκούσιος, ἀκράτεια, βουλεύω, βούλησις, προαίρεσις, φρόνησις