Obama’s already breaking his campaign promises.  But you don’t really need to read the news to know that, do you?  Virtually all successful politicians break their promises.

When you think about it, though, politicians’ penchant for promise-breaking is puzzling.  If making a promise causes voters to like you, wouldn’t breaking the same promise cause voters to dislike you?  Even from a naive perspective, it seems like breaking a promise would cost you all the votes the promise won, and lose you some more votes from people who don’t care about the issue but do care about honesty.

If you’re familiar with the economics of crime and punishment, however, promise-breaking is even more peculiar.  After all, one of the standard conclusions of this literature is that rational victims compensate for imperfect detection of offenses with harsher punishment; they impose “probability multipliers.”  The upshot is that if voters wanted politicians to keep their promises, but had trouble detecting politicians’ betrayals, then any observed broken promise would provoke a shrill – if not hysterical – public outcry: “I will NEVER vote for you again!”

If this sounds hyper-intellectual, let me point out that the public does occasionally use this strategy.  The funny thing, though, is that minor symbolic offenses – a slur, an affair, picayune financial abuse – are much more likely to provoke hysterical outcry than broken promises.

The lesson: The public is already familiar with a strategy it could use to keep politicians on the straight and narrow.  However, the public is too irrational to use this strategy for issues of substance.  In a deep sense, then, politicians break their promises because the public tolerates dishonesty.  Yes, you can blame politicians for lying; but as a wise, old saying goes, “Fool me once, shame on you.  Fool me twice, shame on me.”

OK, I think that explains how politicians get away with breaking promises.  But another question is still open: Why do politicians want to break promises in the first place?  I’ll give my answer later this week.