Nothing comes from nowhere:
The Donald and the Decider, by Paul Krugman, Commentary, NY Times: Almost six months have passed since Donald Trump overtook Jeb Bush in polls of Republican voters. At the time, most pundits dismissed the Trump phenomenon as a blip... Instead, however, his lead just kept widening. Even more striking, the triumvirate of trash-talk — Mr. Trump, Ben Carson, and Ted Cruz — now commands the support of roughly 60 percent of the primary electorate.
But how can this be happening? After all, the antiestablishment candidates now dominating the field, aside from being deeply ignorant about policy, have a habit of making false claims, then refusing to acknowledge error. Why don’t Republican voters seem to care?
Well, part of the answer has to be that the party taught them not to care. Bluster and belligerence as substitutes for analysis, disdain for any kind of measured response, dismissal of inconvenient facts reported by the “liberal media” didn’t suddenly arrive on the Republican scene last summer. On the contrary, they have long been key elements of the party brand. So how are voters supposed to know where to draw the line?. ...
Donald Trump as a political phenomenon is very much in a line of succession that runs from W. through Mrs. Palin, and in many ways he’s entirely representative of the Republican mainstream. For example, were you shocked when Mr. Trump revealed his admiration for Vladimir Putin? He was only articulating a feeling that was already widespread in his party.
Meanwhile, what do the establishment candidates have to offer as an alternative? On policy substance, not much. Remember, back when he was the presumed front-runner, Jeb Bush assembled a team of foreign-policy “experts,” ... dominated by neoconservative hard-liners, people committed, despite past failures, to the belief that shock and awe solve all problems.
In other words, Mr. Bush wasn’t articulating a notably different policy than what we’re now hearing from Trump et al...
In case you’re wondering, nothing like this process has happened on the Democratic side. When Hillary Clinton and Bernie Sanders debate..., it’s a real discussion... American political discourse as a whole hasn’t been dumbed down, just its conservative wing.
Going back to Republicans, does this mean that Mr. Trump will actually be the nominee? I have no idea. But it’s important to realize that he isn’t someone who suddenly intruded into Republican politics from an alternative universe. He, or someone like him, is where the party has been headed for a long time.