Whatever else it may be, crime is mostly neither glamorous nor mysterious. A quotient of antisocial behavior has figured in every known society. In the Denmark of the human soul there is something eternally rotten. Some have peered into the dark heart of criminality and found, not inscrutable evil or anguished reaction to an oppressive system, but untrammeled self-interest. “All the lofty talk about the ‘root causes’ of crime,” writes social thinker Thomas Sowell, “fail[s] to notice the obvious: People commit crimes because they are people—because they are innately selfish and do not care how their behavior affects other people, unless they have been raised to behave otherwise or unless they fear the criminal justice system.”

This reads, plausibly, as a kind of rational actor theory: inasmuch as we all pursue private gain, only inner scruples about the suffering of others or a sensible fear of the consequences can reliably keep our selfish desires from running over, and inundating—as Emerson put it, though thinking of health, not moral sickness—“the neighborhoods and creeks of other men’s necessities.” The idea neatly explains both white-collar crime and street-level offenses. As a corollary to the banality of evil, the mundanity of crime. That something so basic could be so intractable seems perplexing. That it is elemental in us, however, is precisely what has made it a permanent feature of human life.

In his 1987 book A Conflict of Visions, Sowell identified this outlook as part of the “constrained vision” of society and human nature, in contrast with the “unconstrained vision,” whose adherents find it hard to fathom how anyone could commit a crime “without some special cause at work, if only blindness.” But perpetrators always have causes aplenty: profit, prestige, revenge, assertion of self. In the true-crime classic In Cold Blood, a quadruple murder in Kansas baffles local law enforcement: the heinous crime seems to have no motive. In fact, the motive is simple. The killers break in because they believe the man of the house has a safe holding $10,000 or more; finding none, they murder him and his family in anger, and to leave no witnesses.