And therein lies the reason Mr. Romney acts the way he does, why he is running a campaign of almost pathological dishonesty.

For he is. Every one of the Romney campaign’s major themes, from the attacks on President Obama for going around the world apologizing for America (he didn’t), to the insistence that Romneycare and Obamacare are very different (they’re virtually identical), to the claim that Mr. Obama has lost millions of jobs (which is only true if you count the first few months of his administration, before any of his policies had taken effect), is either an outright falsehood or deeply deceptive. Why the nonstop mendacity?

As I see it, it comes down to the cynicism underlying the whole enterprise. Once you’ve decided to hide your beliefs and say whatever you think will get you the nomination, to pretend to agree with people you privately believe are fools, why worry at all about truth?

What this diagnosis implies, of course, is that the many people on the right who don’t trust Mr. Romney, who don’t believe that he’s truly committed to their political faith, are correct in their suspicions. He’s playing a role, and it’s anyone’s guess what lies beneath the mask.

So should those who don’t share the right’s faith be comforted by the evidence that Mr. Romney doesn’t believe anything he’s saying? Should we, in particular, assume that, once elected, he would actually follow sensible economic policies? Alas, no.

For the cynicism and lack of moral courage that have been so evident in the campaign wouldn’t suddenly vanish once Mr. Romney entered the Oval Office. If he doesn’t dare disagree with economic nonsense now, why imagine that he would become willing to challenge that nonsense later? And bear in mind that if elected, he would be watched like a hawk for signs of apostasy by the very people he’s trying so desperately to appease right now.

The truth is that Mr. Romney is so deeply committed to insincerity that neither side can trust him to do what it considers to be the right thing.