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, predicting that voters would soon return to more conventional candidates. 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?

Let’s talk first about the legacy of He Who Must Not Be Named.

I don’t know how many readers remember the 2000 election, but during the campaign Republicans tried — largely successfully — to make the election about likability, not policy. George W. Bush was supposed to get your vote because he was someone you’d enjoy having a beer with, unlike that stiff, boring guy Al Gore with all his facts and figures.