Putting the “Natural” in Natural Law

– by Carlton Patrick

When Clarence Thomas was nominated to serve on the United States Supreme Court, it was Joe Biden, then a Senator from Delaware, who chaired the Senate Judiciary Committee and oversaw the confirmation process. During the hearing, Biden questioned Thomas at length on his views on natural law, saying that while the discussion might “confound the people…whether someone applies natural law is of phenomenal significance, and there is not a single legal scholar you can question who would not tell you that is not true.”

To understand why Senator Biden was so invested in this line of questioning, it is helpful to consider the category of legal disputes that the philosopher Ronald Dworkin calls hard cases. These are instances where a judge must decide a novel controversy that isn’t determined by an existing statute or case law and so the judge must therefore make new law herself. There are countless variations of what principle the judge could use to decide the case. She could decide the case in a way that produces the most equitable or egalitarian result. She could make law that would maximize economic efficiency. Or she could make law that would emphasize conflict reduction, or safety maximization, for example.

But adherents to the natural law philosophy—a list that not only includes Justice Thomas, but also Aristotle, St. Thomas Aquinas, Hugo Grotius, and John Locke—posit that a true, objective set of moral principles exists out in the universe and that laws are only valid to the extent that they conform to this set of principles. Thus, in the face of a hard case, the judge cannot choose among orthogonal principles, and instead must make the positive (or man-made) law accord with the objective natural law that wafts through the ether. Otherwise, the law is simply not valid.

Where do we look to determine these objective principles of natural law? For a long time the dominant theory was that these principles emanate from God(s). Modern defenders of the natural law approach point to a variety sources including Gods, the universe, moral truths, and other metaphysical sources. Regardless of the source, though, most natural law proponents agree that there are certain universal values that are revealed to us through instinct and intuition, and that, as the legal philosopher Jonthan Crowe phrases it “we are characteristically disposed to pursue…and regard them as normatively worthwhile.” Justice Thomas phrases it this way: “the thesis of natural law is that human nature provides the key to how men ought to live their lives.”

What I argue in my article Evolution is the Source, and the Undoing, of Natural Law, is that there is danger in this sort of thinking. Rather than automatically deferring to our gut intuitions, we should investigate where they come from, and use that as the jumping off point for policy discussions about how to make law.

The natural law philosophy derives much of its momentum from the fact that our moral intuitions seem immutable. They are often widely shared, instinctual, robust to temporal and cultural differences. They emerge early in childhood, and are impervious to counter-argument. And it is true that legal codes from vastly different cultures and from different millennia have common features, lending credence to  Cicero’s assertion that the law is “not one thing at Rome, and another thing at Athens” but is instead “universal…unchanging and everlasting.”

But these phenomena can be explained without resorting to superstition. Thirty years of empirically validated evolutionary studies have provided us with a scientific framework for explaining that the reason we share so many moral intuitions, that they show up early in development, and that take on a deontological force is that they are part of our species-wide psychological architecture. They helped to navigate the conflicts inherent in the highly social world of our ancestors where censuring certain actions while praising others would have had significant social consequences. For example, our moral conscience—the intuition that personally taking an action would be the “right” or “wrong” thing to do—helps us accrue praise and reputational clout while avoiding condemnation and punishment. Likewise, our intuitions of justice facilitate the proactive condemnation (and reactive punishment) of certain behaviors by marking those behaviors as ‘wrong’ and attaching an intuitive degree of severity to their wrongness.

Cast in this light, the rubber-stamping of intuition into law urged by the natural law philosophy begins to take on a different view, and many will immediately recognize this as a version of the naturalistic fallacy. By automatically incorporating our moral intuitions into law, we are saying that simply because something evolved, it is per se good, and per se worth institutionalizing. But these intuitions—like all of our intuitions—exist not because they were passed down from a divine arbiter of truth, but instead because they likely granted some fitness advantage to their holder. And, as a result, these intuitions—like all of our intuitions—have the potential to lead us in a wayward direction.

Just as our folk intuitions of physics, economics, or probability can lead us to irrational, inaccurate, or counter-productive conclusions, our moral intuitions can be similarly flawed. They can be selfish, nepotistic, myopic, and capricious. We think the same action is more wrong when it’s done by someone outside of our political group, and less wrong when it’s one of our comrades. We are mortified at the thought of our neighbor’s child dying of hunger but are unmoved when it routinely happens to children living in a Cambodian slum. We flip-flop our moral positions when there is money or reputational benefit associated with doing so. In other words, when consistency in moral judgments runs up against the self-interest of the person making the moral judgment, it is self-interest that often prevails.

In evolutionary terms, these quirks of our moral intuitions are features, not bugs. They would have likely been quite advantageous in terms of navigating the types of recurrent conflicts of interests our ancestors faced. There are no doubt evolutionary advantages to favoring our political allies and our neighbors, or to endorsing different moral positions when doing so would result in a greater economic or coalitional position for us. But, I argue, the fact that our moral intuitions are skewed in these directions is reason enough to give us pause, and to require an argument why (as opposed to a presumption that) they should be used in lawmaking.

Read the original article: Patrick, C. (2023). Evolution is the source, and the undoing, of natural law. Evolution & Human Behavior, 44(3), 175-183.

This article is part of a special issue of Evolution & Human Behavior on Evolution, Justice and Law, edited by Debra Lieberman & Keelah Williams.