Andrew Sullivan views a vote for Ron Paul as a protest against everything the Republican Party has become. Bryan Caplan says that even if he were elected, he couldn't enact the crazier parts of his agenda.
That's fair, but if I'm going to cast a protest vote, I need to know: what elements of Ron Paul's agenda am I going to empower? The problem with expressive voting is that politicians may not actually get the message you're trying to send.
If I vote for Ron Paul, am I ratifying his views on foreign policy, only a small part of which I agree with? Or am I telling Republicans that they should tack to the right on immigration and abortion? And if, in some alternate universe, Dr. Paul got elected, it is true that he would not be able to put the country on the gold standard--but what parts of his agenda might he enact? And who would he appoint to key jobs? One doesn't like to imagine who his nominee for the position of Chairman of the Federal Reserve might be.