In the final two chapters of Nicomachean Ethics Book VI, Aristotle asks some probing questions about thrivings of mind and character.
First, although sagacity [sophia] provides understanding [epistēmē] and insight [nous] into the sources and causes of things, is it of any use in the pursuit of fulfillment [eudaimonia]? Actually, yes. Aristotle reasons that even if sagacity and wisdom did not have practical uses, still they would be valuable because they are excellences of their respective parts or tasks of the thinking soul: grasping the nature of what is in the case of sagacity, and deliberating about how to act in the case of wisdom. Eudaimonia is not merely a feeling (or even a series of positive emotional experiences extended over a lifetime), but the complete development and thriving of your core human capacities, i.e., not happiness in the modern sense but deep and true fulfillment.
Second, because excellences of character like courage and moderation are acquired traits [hexeis], can they function well enough simply with occasional external guidance from others, thus obviating the need to individually cultivate practical wisdom [phronēsis]? Well, no: the task of living a fully human life is brought to completion by one's own wisdom of mind and excellence of character. Specifically, virtue [aretē] establishes the correctness of the target [skopos] you're trying to hit in life, and wisdom establishes the correctness of what brings you closer to doing so.
To further explain the role of wisdom, Aristotle contrasts it with mere cleverness [deinotēs]. The clever person can figure out how to achieve any goal, no matter whether it's beautifully right [kalos] or repulsively wrong [aischros]. The wise person has this ability, too, but it operates in service of the ultimate source [archē] of action, which is the completion [telos] of human capacities and the best thing achievable in action. Whereas corruption [mochthēria] of character warps a person's insights into the source of human action and goodness, excellence [aretē] of character preserves and reinforces such insights, along with the actions that flow from them. Thus Aristotle maintains that it is impossible to be wise without being good.
A similar contrast can be drawn between virtue in the authoritative sense [kurios] and inborn [phusikos] virtue. Some people seem to be naturally courageous or temperate or generous - isn't that good enough? No, because the person who has such inborn virtues can easily go astray without insight [nous]. Indeed, these natural propensities to action merely resemble the excellences of character, whereas virtue in the authoritative sense comes about only through the direction of practical wisdom and the correct account [orthos logos] of one's activities. Yet Aristotle takes things even one step further than Socrates, who said that there is no virtue without wisdom: for he claims that virtue is utterly suffused with the correct account [meta tou orthou logou]. Thus Aristotle concludes not only that is it impossible to be wise without being good, but also that it is impossible to be good without being wise.
Notice that Aristotle formulates no rules for action, nor does he say exactly what the correct account or best form of practical reasoning [sullogismos] is. As I see it, that's because the person who takes life seriously - the spoudaios - uses both sagacity and wisdom to gain insight into the universal sources of the human good and into the particular opportunities for manifesting the good in specific situations. Although it certainly helps to grasp some general patterns of human behavior and principles for action (that's what the excellences of character are all about), there are no hard-and-fast rules for bridging the gap because each situation is unique. This is especially true in human relationships, which are fundamental to the good life because we are social animals; we'll see this come to fruition in Books VIII and IX, a little farther along in our walk with Aristotle.
(Cross-posted at philosopher.coach.)
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