Harold Berman, the late Harvard law professor and author of the great book, Law and Revolution, captured children’s innate understanding of law: A child says, ‘It’s my toy.’ That’s property law,” he said. “A child says, ‘You promised me.’ That’s contract law. A child says, ‘He hit me first.’ That’s criminal law. A child says, ‘Daddy said I could.’ That’s constitutional law.”  Thus, the law has categories that appear to map on to inborn modules of our nature.

As my daughter turns two this week, nothing has been more remarkable to this law professor than her already intense relation with rules, vindicating Berman. Over a year ago, I made a deal with her in the playground: if she got in the stroller when I told her to, I would give her a pacifier. Occasionally, I forget my side of the bargain, and the response is completely different in tone and sharpness than when she simply wants a pacifier.  It is the natural cry of natural justice. A sense of property was present from the earliest times. I think “mine” was the second word we heard after “no.”

It is not only that children have a natural grasp of the justice of certain legal concepts, they also have a sense of the difficulty of drawing lines. Toddlers test rules because they recognize without training that rules can have certain vaguenesses and ambiguities. What exactly constitutes sitting on a chair can be a matter of inches and opinion.

More generally, having a child makes me appreciate all the more the reality of a given human nature that has evolved through millions of years. Madison asked “what is government but the greatest reflection of human nature.” He and the other founders tried to create a Constitution that worked with the grain of human nature. Thus, for instance, its provisions encourage a commercial republic so that the ineradicable self-interest of man becomes an engine of trade and prosperity. But its provisions also impose many checks on government so as to prevent that same self-interest from becoming a source of division and oppression in politics.  Individuals will spend time and money exploiting the vague and ambiguities in even the best rules, just as children do.

The most fundamental divide in politics today is that between those who think that government can change the fundamental nature of man rather than working within the very substantial constraints given by his nature and the environment he inherits at any particular time.  The number of people in the West who never have children is growing. This is unfortunate for many cultural and economic reasons. But perhaps the worse result is that people lose their best opportunity to learn first hand about human nature and its constraints. The more people are childless, the more the impulse to utopianism may grow.