In my review of Hadley Arkes’ book Constitutional Illusions I criticized Arkes’ account of natural law ethics. My main complaint was that Arkes’ aspirations for what natural law ethics could accomplish were unrealistic, and that in particular his argument for grounding morality in “laws of reason” such as the principle of non-contradiction was unsuccessful. Now Professor Arkes has issued a friendly challenge to me in reply: If he is wrong, then what’s the alternative? And in a healthy Socratic spirit, Arkes wants examples. How would I demonstrate the wrongfulness of racial discrimination, for instance, if not by showing that racists necessarily contradict themselves?

Before taking this question on directly, I want to address some general themes in natural law ethics. I should also emphasize some important points of agreement between us. Both Arkes and I agree that the source of morality is human nature, that human nature is essentially a rational nature, and that moral truths are discoverable through reason apart from revelation. We also agree that if a basic moral principle is true, then it’s necessarily true. So if knowledge, for example, is a basic constituent of a good human life then knowledge is a constituent necessarily. Somebody who neglects to cultivate knowledge lives a more impoverished, shallower life than somebody who does.

Now to the general themes. In Arkes’ reply he makes an important and very un-Kantian aside that needs to be fleshed out, because it’s in tension with the ambitions of his book. In discussing the formal character of moral laws he remarks,

I should point out that nothing in this apparatus of reasoning could tell us what counts as hurt or harm among human beings. For that we need to be aware of life as lived. But once we are aware of a harm that calls out for justification, the principles of justification kick in with their real force.

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Being “aware of life as lived” strikes me as indeed the only way to learn about human welfare and harm, but if this is true, then much else of what Arkes says about the natural law rings hollow. Let me explain. In the aside, Arkes seems to be conceding the Aristotelian observation that knowledge about human welfare and harm depends upon having achieved a certain reflective maturity, having had the right breadth of experience, and having cultivated the right habits of feeling and acting. But these prerequisites to moral knowledge make moral argument limited and highly contingent in what it can produce, because it means that many moral failures will consist in people failing to perceive the bad in what they do, since they haven’t rooted out certain vices by acquiring their contrary virtues.

There is no reason to think that such failures of moral sensibility must include errors of self-contradiction as well. The Kantian aspiration, shared by many modern moral philosophers, is to abstract from such troublesome contingency by relocating the source of moral knowledge to, in Kant’s words, “the general concept of a rational being as such,” so that moral rules can be shown to anybody to compel compliance on pain of formal contradiction. From the outset, the expectation is for answers that will convict an immoralist of self-contradiction; if you can’t produce answers in this way, then you haven’t given a properly moral argument. In chapter two of Constitutional Illusions, which is the heart of Arkes’ account of natural law, Arkes unmistakably shares this aspiration. After all, it’s a quite understandable one to have, since it would be extremely helpful if moral philosophy could demonstrate to any average adult the logical incoherence of acting immorally.

Arkes claims that the natural law “does not depend on religious beliefs, ever evading the test of reason” because the “natural law has ever been bound up with ‘the laws of reason’ and the laws of reason find their own touchstone, or their anchoring ground, in the law of contradiction” (63). He argues that moral principles are genuine moral laws and

…what we mean by the ‘moral laws’ is nothing more than those laws of reason themselves. They are the laws of reason, the canons of logic, that command our judgment in the domain of freedom…. [Moral laws] are ‘laws’ only if they have about them the quality of necessity. And they can have that quality only if they find their ground indeed in the ‘law of reason’ strictly understood—in propositions we cannot deny without falling into contradiction (64).

Now there is some wiggle room in phrases like “find their own touchstone” and “ever been bound up with,” but Arkes’ claim seems to be this: Insofar as somebody is a rational agent, then he is by definition free and responsible, and his chosen actions will be subject to those norms that are constitutive of rational agency. These norms, which are the laws of reason, just are the moral laws for creatures whose nature is rational.

The problem is that all this apparatus is idle, even when supplemented with an Aristotelian moral sensibility. There’s no reason to think that the wrongfulness of unjust actions, for example, will be demonstrable through “principles of justification” that are generated from whatever norms are constitutive of rational agency. For pace Arkes, many qualities of people that are deeply significant for determining how we should treat them in justice and friendship are arbitrary and unchosen. There’s at best a negligible sense in which I chose to be an American, and no sense at all in which I chose my sex or to have the relations of kin that I do. Even my chosen friends were first my unchosen acquaintances, since who these were was mostly beyond my control. But all these arbitrary features of and relations to me determine what justice and friendship require of me, and in turn what I am owed by others. A “rational being as such,” on the contrary, doesn’t have a mother, father, siblings or a wife, friends or a nationality, and so the “morality” of a purely rational being will be unable to express a whole swath of human moral concerns.

I doubt that Arkes will want to deny much of what I’m arguing for, but I fear that his theory forces him to—so long as he maintains the Kantian aspiration to generate moral justification from rational consistency and requires moral arguments to apply with the force of necessity. I’m not making a pedantic complaint that Arkes has misconstrued the historical Kant or Aristotle. Rather, I’m suggesting that his version of natural law is at cross-purposes with itself. I’m also not just making a point about the limits of persuasion, because my argument is about what a moral demonstration could be, even under ideal conditions.

Let me sketch an alternative approach. The way to begin reflecting on morality is not with a question like, what must I do and what must I avoid? Rather, we should begin with the question, what do people need in order to live? Next, we should ask, what do people need in order to live well? Beginning with these questions encourages us to translate talk about moral right and moral wrong into talk about specific virtues and vices. This is felicitous, because morality is primarily about choosing good actions that express virtues of character and only secondarily about conforming to juridical categories of the morally right and permissible. The term “natural law” points to these two facets of morality: the naturalness of the natural law consists in the virtues that fulfill our nature as rational animals and the legality of the natural law consists in the social character of how that fulfillment plays out. When the order of these two idioms gets inverted, then people are prone to ask sensible-sounding but incoherent questions such as: “Granted that depriving Jones of care would be unjust, might we be morally obliged sometimes to do what is unjust?”

The legality of the natural law—what makes the natural law to be law—is the fact that human flourishing is a common enterprise among people living together. Common enterprises need coordination in order to be sustained and law is the instrument of coordination par excellence. But law, as Thomas Aquinas recognized, needs a lawgiver to legislate and promulgate it. Otherwise a “law” is just an ordinary rule, and an ordinary rule may be good or bad to follow, but in either case is not rationally obligatory. When a traditional Jewish, Christian, or Stoic God is in the picture, it is very easy to see how the natural law is really law that applies with the force of obligation, because God’s role as the legislator of nature’s lawfulness is unmistakable.

Without God in the picture, however, the obliging force of morality is much less evident. Therefore, it is not true to say that knowledge of the natural law is independent of theology, as Arkes implies, because knowledge of the natural law as law requires knowing its authoritative source in God. This is a point that natural law theorists would do well to consider when making political arguments in the public square. The obliging force of morality, if not its content, depends upon whether or not you think God commands us to acquire the virtues. In other words, it depends upon whether or not you think that the common enterprise of living well together includes as chief member God himself.

To return now to Arkes’ first challenge: how do we demonstrate the viciousness in racist discrimination or of deliberate neglect of the disabled? There is no quick and easy argument. We demonstrate this by carefully reflecting upon our personal and social history, the consequences of racism and neglect, the nature of human animality, and the unspoken ways in which every one of us is dependent upon other people for our happiness. By sifting through this data we can produce an argument, which will ring true for the person who has cultivated the right sensibility, for the proposition that all human beings have an inalienable moral dignity.