In Book 6 of NE, Aristotle deals with the problem of exercising “correct reason” in radically uncertain situations. This problem had been emerging in NE and is resolved in his discussion of phronesis (translated by Bartlett and Collins as “prudence”) in 6.5. Leading up to this, we have 6.3’s discussion of “science” (episteme) and 6.4’s discussion of the difference between “making” (poeisis) and “moral action” (praxis). “Correct reason” functions differently in each one of these situations, and the difference has to do with how much certainty one can seek in each undertaking.

To start out this discussion, we are told in 6.1 that reason is a separate faculty of the soul and that it can be further subdivided into two: “one part is that by which we contemplate all those sorts of beings whose principles do not admit of being otherwise, one part that by which we contemplate all those things that do admit of being otherwise” (1139a 7-9, emphasis added). From here, he goes on to align each subdivision of reason with ways of knowing — “the scientific” deals with “beings whose principles do not admit of being otherwise” and “the calculative” (which he equates with deliberation) deals with “those things that do admit of being otherwise.”

These admittedly awkward phrases recur frequently in the translation, and they are important. I have found them to be essential in being able to make sense of this difficult work. Things that cannot be otherwise are things that can be known for certain — that animals need to breathe to live, that the sky is blue, that rain is wet. No matter how hard you try, these facts will not change. These kinds of certainties are the province of science (episteme) as discussed in 6.3. Because there is a fundamental stability in scientific knowledge, its findings are teachable and subject to demonstration.

“Things that can be otherwise” refers to the subdivision of reason that deals with the desired outcomes. Because these “things” don’t yet exist, they “can be otherwise,” and it is human action that will bring them about. Aristotle’s typical examples are things like ships, houses, justice and military victory. These things are the result of knowledgeable human beings making decisions and taking action. Most of human life is about this use of reason and it is the essential topic of NE.

This kind of reason is further subdivided into reason that is related to “making” (poeisis) versus reason related to “moral action” (praxis). Aristotle seems to stop short of identifying two faculties of reason, but he does insist that there is a distinction within human reason. It can operate differently in different circumstances.

The main difference has to do with the level of certainty involved in one’s undertaking. Making houses is an art (techne), and as such there are some definite certainties — a weak foundation will cause the house to crumble; if you don’t build at least one door, you can’t get in or out. But what the house will look like, how big it will be and where it will be are uncertainties — they “can be otherwise” and are thus determined by the decisions made in the process of siting, designing and building. So an art is not a science because the things we make are up to us, but there are still some certainties that must be respected to be a good maker.

Aristotle is clear that “true reason” and “false reason” are the defining differences that determine whether or not one is good at the chosen craft (1140a 20ff). Here we clearly see that reason, while it is a distinct faculty of the human soul, is not ahistorical. When it comes to “things that can be otherwise,” reason is measured by its ability to bring about good outcomes. For shipbuilding, the ship must be fit for purpose — transporting troops, defending a coastline. The purposes and the techniques for attaining them can be relatively certain. Learning and practicing them leads to “true reason” as a ship builder.

When it comes to moral and political action (praxis), however, uncertainty is far more fundamental and pervasive. In the absence of certainty — I’ll call it radical uncertainty — reason has a different job to do. It cannot drive to scientific certainties, nor can it even rely on the established rules of an art form like carpentry, ship building or house making. Rather, it must rely on virtues — the values we bring to the deliberative process to try to reach a good outcome.

In particular, Aristotle singles out at this point in the discussion (6.5) one particular virtue — prudence (phronesis) — as the virtue that helps us manage good outcomes in the face of radical uncertainty. For Aristotle, “prudence is a certain virtue and not an art” (1140b 25). So prudence is not a science and not an art, but it is aligned with the kind of reason that deals with actions and desired outcomes when the predictable rules and techniques of an art are not available. Prudence, therefore, directs “correct reason” in these uncertain situations and not the other way around.

How does prudence work?

First, prudence is earned over time and is the result of experience and the building of one’s character. It is built into one’s self through prolonged experience and is therefore emphatically differentiated from “wisdom” (sophia) in 6.7, which is much more easily achieved because it is concerned with certainties that can be taught. In 6.8, he discusses how the young are generally lacking in prudence though they can certainly be knowledgeable through learning “abstractions” (scientific truths) that can be memorized and demonstrated. What is more important, is that prudence makes one’s knowledge useful because it is oriented to achieving human good. Anaxagoras and Thales are “wise” but not prudent. They know a lot, but had no idea how to translate that into good outcomes for others. In this respect, their knowledge was “useless.” In a different example, one can know with certainty that white meats are more easily digestible than dark meats and thus more conducive to health. But if you don’t have the practical knowledge of which ones are light and which ones are dark, your knowledge is utterly useless for the purposes of facilitating human health. (6.7 1141b 15)

Second, the fundamental skill of the prudent person is deliberation — the ability to lead oneself and others to the actions and outcomes that best promote the human good:

But prudence is concerned with the human things and with those about which it is possible to deliberate. For we assert this to be the work of the prudent person especially — deliberating well — and nobody deliberates about things that cannot be otherwise, or about so many things as are without some end, an end, moreover, that is a good attainable through action. He who is a good deliberator simply is skilled in aiming, in accord with calculation, at what is best for a human being in things attainable through action. (1141b 10, emphasis added)

Third, prudence is the ability to apply universals to particulars, but with privileged sensitivity to the uniqueness of the particulars. Aristotle continues from the previous passage cited:

And prudence is not concerned with universals alone but must also be acquainted with the particulars: it is bound up with action and action concerns the particulars… As a result, one ought to have [knowledge of] both [universals and particulars], but more so of the latter. (1141b 15-20)

Because prudence is the virtue that deals with radical uncertainty in morally and politically relevant situations, it cannot rely on universals (i.e., settled certainties of science or the relative certainties of making houses and ships). The prudent individual understands which universals are relevant, but does not let them overrun the details of the situation.

Fourth, because prudence is an aspect of character built up over time and is also the virtue that animates “good deliberation”, it is implicitly tied to Aristotle’s Art of Rhetoric. But, prudence gets short shrift in that work, and it’s worth asking why. I believe it’s simply because the Rhetoric is concerned with how one convinces others of a course of action about which the speaker has already come to his own deliberated conclusion. NE, particularly in Book 6, is about how to do that deliberation and reach that conclusion for oneself. The Rhetoric, then, is about how to stage that conclusion for an audience and lead them to your point of view — but only after you’ve reached it yourself. There is no public conversation in the Rhetoric. Rather, there are carefully crafted speeches that must be judged by the audience. In this sense, the Rhetoric can be seen as anchoring the lessons of character formation of NE in the existing political institutions of “the city” where speeches and voting are the essential political tools.

Finally, if prudence is not aligned with the demonstrable certainties of scientific knowledge nor with the predictable techniques of an art, it is mostly aligned with “management” and the ability to govern oneself and others. In 6.8, Aristotle turns from prudence as a personal virtue — the ability to decide and bring about what is most advantageous to oneself — to prudence as an art of governing others. Specifically, he defines three kinds of prudence: “one part is household management, another legislation, another the political art; and of this last, one part is deliberative, the other judicial” (1141b 31ff).

Prudence is thus inserted back into art (techne) — the art of politics, the art of legislating and the art of managing a household of wives, children and slaves. But now it is the animating virtue in arts that deal with radical uncertainty. Aristotle must therefore focus the discussion in 6.9 on defining “good deliberation”, which ends up being the fundamental technique of prudence. In other words, it is how prudence is demonstrated and enacted. Thus we end up back at an art — the art of politics (which is where NE started in the first place) — but an art that is fundamentally different than building ships and houses. Things are a lot less predictable and highly uncertain in politike. All you have is your experience-driven character, your ability to deliberate through complex situations, and your ability (in the Rhetoric) to convince others that your course of action is the best for all.

So what is good deliberation? It is the ability to see the whole picture in a radically uncertain but morally and politically relevant moment that one is facing and marshaling the virtue of prudence to get the best outcome in the circumstances: “it is the correctness that accords with what is beneficial and aims at what one ought, in the right manner and at the right time” (1142b 25).

So if having deliberated well belongs to those who are prudent, good deliberation would be a correctness that accords with what is advantageous in relation to the end, about which end prudence is a true conviction.

The prudent person is one who, through experience over a long period of time, has developed the ability to figure out what the best outcome is in any given morally and politically relevant situation and to enact and persuade others on that best course of action. She has a right respect for the particulars of any given situation and will not subordinate those particulars to the dogma of universals.