If you start from the conviction that you’re standing up for the underdog, you will naturally assume that your political opponents are for the powerful. You will subliminally screen out evidence that challenges that view. As Danusha Goska put it in American Thinker not long ago, “Never, in all my years of leftist activism, did I ever hear anyone articulate accurately the position of anyone to our right. In fact, I did not even know those positions when I was a leftist.”

Do rightists also caricature their opponents? Yes, but not to anything like the same extent. A 2012 study by Jesse Graham, Brian A. Nosek and Jonathan Haidt asked conservatives and liberals to answer a series of questions as themselves, and then to answer them in the imagined personae of a typical conservative and a typical liberal. It found that the liberals were the least able to accurately to guess their opponents’ views, seeing conservatism as a kind of moral failure.

They’re not playing to the gallery. They’re not sloganizing. They genuinely believe that we conservatives went into politics because we hate the poor. Their conviction is so solid that facts crash against it as waves against a rock. Again and again, leftists will line up behind policies that hurt the general population in order to reward vested interests: the bailouts and the TARP boondoggle, the alternative energy scams, the trade barriers that favor privileged industries, the regulations that drive up prices. The practical consequences of these policies matter far less to their advocates than the opportunity to signal their good intentions. And if their intentions are good, ours must be bad. Psychologists call it “self-serving bias”.