When I was an undergrad at UC Berkeley, there was an informal norm about professors dating their students: Just wait until after the final exam.  Professors dating their current students?  A recipe for corruption.  Professors dating their recent students?  Only the prudish could object.

You might dismiss this as a weird Berkeley norm, but it’s also ubiquitous in American politics.  Consider:

If a major corporation gives a U.S. Senator a ten-million-dollar “gift,” it’s likely to be punished as corruption.  It doesn’t matter if the corporation protests, “We’re only expressing our affection for this fine Senator” or if the Senator bellows, “How dare you claim my vote is for sale!”  However, if the same Senator retires, and the major corporation gives him a ten-million-dollar sinecure on its Board of Directors, it’s perfectly legal – and few demur.

The painfully obvious flaw with both norms: Intertemporal corruption is a wonderful substitute for ordinary corruption.  A professor is unlikely to give an F to his current girlfriend; but he’s also unlikely to give an F to his future girlfriend.  A Senator is unlikely to vote against a corporation that gives him millions of dollars; but he’s also unlikely to vote against a corporation that’s going to give him millions of dollars.  What comes around, goes around.

You could object that intertemporal corruption is less reliable than ordinary corruption.  True, but the magnitude of this reliability difference is probably small.  Gratitude and resentment are deeply-rooted human emotions.  We like to repay kindness with kindness, affront with affront.  And whenever emotions fall short, reputation picks up the slack.  How hard can it really be for corporations to predictably hand out sinecures to their retired political cronies?

An alternate objection is that punishing ordinary corruption is much easier than punishing intertemporal corruption.  But if we learn anything from the economics of crime, we learn that the severity of punishment should go up when the probability of detection goes down.  So instead of throwing up their hands about intertemporal bribery, crusaders against corruption should sharpen their pitchforks.

There is one last intellectual escape route: Say that anti-corruption efforts are misguided in the first place.  Quit your bellyaching; it doesn’t really matter if professors date their students, or if corporations have politicians in their pockets.  But few will want to bite this bullet, at least publicly.

Other attempts to explain our puzzling tolerance for intertemporal corruption?