Prof Mankiw claims, piously:

Sin taxes try to correct for behavior that some social planner deems as not sufficiently virtuous

in the process of trying to make a distinction between "sin taxes" and "pigovian taxes". Apparently, pigovian taxes try to correct for behavior which some economist finds to be an offense against economic morality. Oh, I'm sorry, he says "negative externalities", as if that means something other than an economist's notion of virtue.

I'll just note that no legislature has ever enacted a law in favor of the actions of gravity, but there are many which have tried to repeal the laws of thermodynamics.