Welcome to what I've called "the politics of self-esteem." By this, I mean that increasing numbers of people, on both the right and left and most with good intentions, have become politically engaged because it makes them feel better. It raises their self-esteem. This phenomenon predates Donald Trump's candidacy, but it helps explain a Trump puzzle that baffles many observers.

By now, the puzzle is familiar. Trump repeatedly says things that seem (by conventional wisdom) hateful, offensive, stupid or simply wrong. But instead of these apparent missteps backfiring — sowing doubt about his competence and moral values — just the opposite happens. The more Trump flouts prevailing norms, the more popular he becomes among Republicans. The latest example: After proposing a widely criticized ban on all Muslims entering the country, his support among Republicans jumped to 38 percent in December from 32 percent in November, according to a Washington Post-ABC News survey.

Trump has not redefined politics, but he has exploited a fundamental change of recent decades. Since World War II, much of national politics has involved a struggle for economic benefits. In 1940, the government transferred about 7 percent of national income from some groups to others. Now, that share is nearly 20 percent. This remains a huge part of politics, as debates over highway spending, farm subsidies, taxes and so much more remind us. But spending decisions are incremental; sweeping shifts are unlikely. We're not going to abolish Social Security.