President Trump’s victory in Iowa — where he won an absolute majority in a four-person race — will certainly put a spring in his step. It might not be, history suggests, a reliable predictor of who will emerge as the party nominee. The landslide by which he trounced two strong Republicans, though, is remarkable. It goes a long way in putting paid to the notion that, as Conrad Black puts it, the 45th president is a spent political force.