The following is an excerpt from Stoicism as a Warrior Philosophy: Insights on the Morality of Military Service, by Commander William C. Spears, USN, adapted for publication at The Stoic magazine.

The central claim of the Stoic philosophy is “virtue is the sole good.” With clarity and force, it provides the keystone in a vast arc of Stoic moral reasoning, without which the system collapses into a heap of motivational quotes and folk wisdom. Stoicism cannot stand as a coherent philosophy without it. And yet, in most portrayals of Stoicism, virtue receives little attention, crowded out by preoccupations with emotional resilience and self-control— qualities that, as we shall see, are simply specific expressions of virtue. When virtue is discussed at all, it is typically assumed everyone understands what it means. But is that a safe assumption?

We would do well to clarify what the Stoics mean when they say virtue is the sole good.

First, we must recognize we are relying on translations, and some meaning may inevitably be lost in that process. The Greek word we render as virtue is aretē, which refers broadly to qualities of goodness, excellence, or perfection. However, we must bear in mind this concept is not solely a human quality; for instance, a horse can have virtue if it runs well and a knife can have virtue if it cuts well.

Virtue, then, must be understood broadly as goodness in a descriptive sense, and it is well to have clarified this point. With this understanding in hand, we return to the keystone concept, which can now be rephrased with a straightforward substitution. We arrive at the profound claim that… goodness is the sole good?

Now, that is not helpful at all. Something must be missing. Aretē, or virtue, must refer to something a bit more specific than goodness. We may say it is goodness, but goodness at what? Goodness to what end? Let us return to our examples: a horse could demonstrate virtue if it runs well and a knife if it cuts well. On the other hand, let us imagine a horse that produces excellent milk. This would not be a reason to say it is a good horse. Likewise, a particular knife may be very effective in striking blunt objects, but that would not make it a good knife. Virtue, as befits our examples, appears to mean something like goodness toward a specific mission, or goodness at being what something is supposed to be.

The next question practically leaps out at us: by what criteria can we say a human is being what one is supposed to be? Stoics would say we can start by ruling out anything a human cannot control. For example, physical attributes, like height or skin colour, are not really up to us, so they can have no bearing on whether or not we are being what we are supposed to be.

Extending this reasoning, we can rule out wealth, reputation, companionship, and anything else not really up to us. Our actions may influence such things, but in the end they are external to us; they can be taken away at any moment for any reason. Because our virtue refers to us, and not these features external to us, what remains as the virtue of a human are internal factors, or what we might otherwise call moral factors.

The word moral warrants further clarification. In popular perception, morality might call to mind values such as forgiveness or chastity, a reflection of the deep influence religious traditions have had in shaping social values. While such priorities are not without merit, some individuals may associate morality with a kind of ‘softness’ or naivety, reminiscent of the lessons we teach to children. As a result, some readers may be inclined to dismiss discussions of morality as an irrelevant or even undesirable regression.

However, there is much about morality that is not taught in children’s books. In the sense that I use it, morality refers to all traits of character that make up who we are and who we aspire to be. It captures every kind of ‘hardness’ an individual might wish to cultivate, excepting perhaps the literal density of muscle tissue, but not excepting the personal discipline required to achieve it. Qualities like fortitude, work ethic, wisdom, and reliability under stress are moral factors, and insofar as Stoicism is useful or interesting at all for application within the modern world, it is as a moral philosophy.

Virtue, as befits a human being, is moral perfection. In the language of the Stoics, then, moral perfection is the sole good, and this is what it means to live “in harmony with nature.”

Commander William C. Spears is a submarine warfare officer in the United States Navy and author of Stoicism as a Warrior Philosophy: Insights on the Morality of Military Service. All opinions expressed in this article are his alone and do not constitute an official position of the United States Government or any government organization.

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