As we watch the left of the Democratic Party press its case to return to the top of the heap in American politics, or at least evade the fate of the Dodo, we have ever more evidence validating an insight on which I stake my reputation as a political seer. To wit: partisan politics more often falls under the professional expertise of the psychiatrist than that of the political scientist. A learned shrink can often tell us more about a political issue than any other professional, not excluding a swami or a voodoo priest. Consider the ongoing controversy over Sen....