By any objective measure, it’s of course unjust to fire a man for one errant remark. Politics, however, isn’t fair, and neither is the presidency. Mr. Romney’s problem is not his policies or programs; his problem is his credibility: many people just don’t believe he really believes what he is telling us. Firing Mr. Fehrnstrom would be a welcome signal that Mr. Romney is offended by any suggestion, no matter how much it might be later explained away, that he does not really believe what he says — and is ready, willing, and able to erase it away when he thinks he needs to. The worst part is that Mr. Fehrnstrom does not appear to have chosen unfortunate words that distort what he ways trying to say. To the contrary, his problem is that he appears to have inadvertently expressed what he, and by extension the Romney campaign, really does think.