Some public figures get defined by a single image, or a single statement ("Ask not what your country can do for you"; "I am not a crook"). Others have a characteristic linguistic tic or hand gesture that through repetition come to embody them; think of Ronald Reagan's head shake, George W. Bush's shoulder-shimmy, or that closed-fist-with-thumb-on-top thing Bill Clinton used to do.
For Mitt Romney, it's the laugh. I'm sure that at times Romney laughs with genuine mirth, but you know the laugh I'm talking about. It's the one he delivers when he gets asked a question he doesn't want to answer, or is confronted with a demand to explain a flip-flop or a lie. It's the phoniest laugh in the world, the one New York Times reporter Ashley Parker wrote "sounds like someone stating the sounds of laughter, a staccato 'Ha. Ha. Ha.'" Everything Mitt Romney is as a candidate is distilled within that laugh—his insincerity, his ambition, his awkwardness, and above all his fear. When Mitt laughs that way, he is not amused. He is terrified. Because he knows that what he's saying is utter baloney, and he knows that we know it.
So he pretends to find it hilarious that an interviewer wants him to explain why, say, Romneycare was great for Massachusetts but the nearly identical Obamacare is a Stalinist horror for America. Perhaps it is the pain of enacting this facsimile of delight so many times that has hardened Mitt's heart and allowed him to run what has become a campaign of truly singular dishonesty. But whatever moral calculation underlies the decisions he makes, this is the place we have arrived: There may have never been a more dishonest presidential candidate than Mitt Romney.