I think Will Wilkinson failed to understand Matt Zwolinski’s argument about the significance of the miniscule level of voluntary donations to the U.S. government.  But this is also an ideal time to defend a related, underrated argument.  I call it the Argument from Hypocrisy.  It goes something like this:

1. Lots of people say that X is wrong.

2. But these people almost always do X.

3. Therefore, even the opponents of X don’t really believe X is wrong.

4. So X probably isn’t really wrong.

As stated, I freely admit that the Argument from Hypocrisy seems laughable.  But it’s stronger than it looks.  We just need to add a some extra steps to the argument.  Here’s my fleshed-out version:

1. Lots of people say that X is wrong.

2. But these people almost always do X.

2.1. An individual’s sincere moral beliefs have some effect on the individual’s behavior.  All else equal, the probability of doing X increases as the moral evaluation of X rises from morally unthinkable to morally impermissible to morally permissible to morally good to morally right to morally obligatory.

2.2. People are pretty selfish, but they’re rarely self-conscious villains.  So an extreme disparity between behavior and moral beliefs usually indicates an absolutely low level of confidence in the moral beliefs.  Consider people who claim that we are morally obliged to give all our surplus wealth to the poor.   If, on average, they give just 3% of their surplus wealth to the poor, this is a strong sign that few sincerely find their official position convincing.

3. Therefore, even the opponents of X don’t really believe X is wrong.

3.1. If even the opponents of X have little confidence that X is wrong, X probably isn’t wrong.  Why?  For starters, because humans have strong “myside bias.”  If even the faithful can’t talk themselves and each other into believing that X is wrong, X is probably isn’t wrong.

4. So X probably isn’t really wrong.

This fleshed-out Argument from Hypocrisy is hardly airtight.  But it’s not supposed to be.  Like most good arguments, the point of Argument from Hypocrisy is not to evoke absolute certainty, but to tilt your probabilities.  Widespread hypocrisy about X really is a reason to disbelieve X.  A pretty good reason, in fact.

P.S. If you don’t buy the Argument from Hypocrisy in general terms, how about the subset of hypocrites who habitually commit actions they claim to believe will be punished with eternal suffering?