Donald J. Trump won the white working-class vote over Hillary Clinton by a larger margin than any major-party nominee since World War II. Instead of this considerable achievement inspiring introspection, figures from the heights of journalism, entertainment, literature and the Clinton campaign continue to suggest that Mr. Trump won the presidency by appealing to the bigotry of his supporters. As Bill Clinton recently said, the one thing Mr. Trump knows “is how to get angry white men to vote for him.” This stereotyping of Trump voters is not only illiberal, it falsely presumes Mr. Trump won because of his worst...