The problem is not that the electorate is polarized, siloed into self-reinforcing media echo chambers and mutually contemptuous — that’s the cause. The problem is that neither the partisans of the left nor those of the right can imagine themselves, for even a second, on the other side of the ideological divide.             This phenomenon is perfectly illustrated by the spectacular rise of Donald Trump’s Republican primary poll numbers, first following his indictment for business fraud by Manhattan district attorney Alvin Bragg, and then after Florida Governor Ron DeSantis announced his run. According to conventional (liberal) wisdom, both these events should have hurt Trump politically. What the heck, Democrats wondered, is going on with those wacky GOP voters?             Donald Trump thinks, at least he claims he does, that the deep state and the media are out to get him. Judging the long list of congressional investigations, Justice Department inquiries (which were subsequently determined to have been unjustified), multiple…