In the NYT, the philosopher Jeff McMahan argues that torture is almost always morally wrong, but he believes that in certain cases–when it is used to prevent a greater evil like killing or mass killing–it is morally permissible or even morally obligatory. Yet he believes that torture should be banned even then. That doesn’t seem to follow. If McMahan’s moral position is correct, shouldn’t the law permit torture just in those conditions when it is morally permissible, and otherwise ban it?

As far as I can tell, his answer is that morally justified torture may be so rare that it can be safely ruled out by an absolute ban. That may well be right; maybe that is the lesson of the Bush torture debacle. But it does seem puzzling. Consider shooting-to-kill. Shooting-to-kill is also a horrible thing to do to people (worse than all but the most extreme forms of torture), and it is rarely justified. Yet police officers are permitted to shoot-to-kill in order to prevent greater evils. Even after recent events suggesting abuse  and discrimination in police shootings, no one wants to impose an absolute ban on them.

McMahan, like other philosophers (such as Henry Shue, who is mentioned in the piece) who both want to ban torture but believe that it is sometimes morally justified, can’t bring himself to enforce the absolute ban with absolute strictness. Instead, courts should be allowed to exercise leniency. Yet McMahan appears to believe that the agent cannot be excused. Some punishment (a very light punishment?) must be imposed.

But why exactly? Why would you punish (even lightly, as in this famous German case) someone for engaging in a (by hypothesis) morally permissible or even morally obligatory act of torture? The answer seems to be that if you don’t, then other agents will engage in torture that is morally wrong. I confess I have never understood this argument. Doesn’t the logic of it suggest that we should prohibit the police from morally justified shootings because if we don’t, police will engage in morally unjustified shootings?

Or taken from the other side, if leniency is permitted, why shouldn’t we worry that the prospect of leniency will encourage agents to engage in wrongful acts of torture? After all, if non-punishment of morally justified torture will encourage wrongful torture, as McMahan claims, why wouldn’t lenient punishment of morally justified torture also encourage wrongful torture? The effort to split the difference by banning torture but providing for leniency seems arbitrary.

Let’s go back to police shootings. Possibly, torture can be distinguished. One distinction is that police shootings are usually (almost always?) morally justified, whereas acts of torture are almost never morally justified. But do we actually know this? The reason that police shootings are usually morally justified, or seem to be, is that the police are given training, and police shootings are always investigated carefully. There is no comparable institutional infrastructure for torture. Maybe if there were, acts of torture would seem as morally justified as police shootings (although no doubt much rarer).

Arguments like McMahan’s, which are scattered throughout the philosophy literature, always seem to be based on psychological (about how people respond to incentives) and institutional assumptions (about how organizations operate) that are not articulated.