“Of all inquiry most beautiful,” Socrates affirmed in the Gorgias, is inquiry “about what sort of man one should be.” Both in the classical world and in the later intellectual traditions that absorbed its influence, successive generations of thinkers have shared Socrates’s sense of significance and made it a central part of their ethical task to articulate a vision of the highest human character. For some, especially in religious traditions, ideals of character have taken their place in a more complex understanding of the mode of life to which the revealed word summons—a mode of life in which, at its most rigorous, every action, thought, and feeling has its measure and norm. The modern novel brought to us the imagined possibility of an all-knowing introspection into the privileged space of another’s mind. But that possibility had been imagined far earlier by thinkers working out the consequences of their religious convictions. God is closer to people than the jugular vein, the Qur’an says (50:16). He “perceives your inmost notions and the deepest thoughts that streak through you,” as Abū Ĥāmid al-Ghazālī put it in his spiritual masterpiece, The Revival of the Religious Sciences. Or again, in an arresting image that appears throughout the same book: God sees the black ant that creeps over a dark stone in the dead of night—and the things that creep in the soul are no less pernicious for being exquisitely hard to detect. The human mind is always permeable by the mind of God and answerable to its measures.
“Measure” is a good word with which to ease into some of the most interesting questions this vision of the moral life raises. If what we should care about is to become a certain “sort of man,” in Socrates’s words, just how exactly is the right sort decided? What sets its measure? Philosophers approaching these topics have sometimes parsed this point laconically as the question “What makes a character trait a virtue?” To some, the question may seem idle: many of the qualities we value are so obviously important that doubt can only look contrived. Who would doubt, for example, that temperance, compassion, or justice are qualities that it is good for human beings to have? It is a question that takes its edge, to be sure, from disagreement—the kind of disagreement that Hume ignited when he denied that humility is a virtue, or Nietzsche when he denounced compassion. Yet it is rare for the question “why?” to be asked without profit. Even without such polemical starting points, asking about the measure of human virtue can tell us volumes about the larger moral universe that gives meaning to its pursuit. Even where there is broad convergence about which traits are virtues—and the existence of such convergence is one of the more remarkable facts about character-based ethics, grounding precious possibilities of cross-cultural and inter-religious moral conversation—different schemes may incorporate such varying conceptions of the nature of reality, and of human nature, that what divides them may seem almost as important as what unites them.
For many philosophers, ancient and modern, this question “why?” has opened out to a very particular response, and conception of measure. The measure of the virtues, on this view, is nothing less than human nature. This is a view that has sometimes been read out of Aristotle, whose celebrated argument about the human “function” in the Nicomachean Ethics shadows his account of the specific virtues. The function of human beings, in Aristotle’s account, lies in the actualization of their rational capacities. On one plausible interpretation of the progress of Aristotle’s discussion, qualities like temperance, courage, or justice are thus virtues taken as actualizations of reason across certain domains of universal experience that human beings must inescapably negotiate. No human being could go through life without learning to handle bodily appetites and pleasures (cue temperance). No human being could go through life without learning to handle fear (cue courage).