The big story going into tonight’s primetime debate in Cleveland is Donald Trump. Right now he’s the frontrunner. Whether that lasts or not remains to be seen, but for now, he’s riding high. And he’s doing so in part because some people on the right are rallying to his side — speaking favorably of him, defending him, holding him up as a model.

In that sense, Mr. Trump is performing a useful service. For years, there have been figures on the right who have presented themselves as people of deep philosophical convictions. They portray themselves as champions of limited government, willing to take unpopular stands in the effort to advance their ideology, utterly fearless in their pursuit of conservatism. They were true believers — the heirs of Reagan — willing to call out the RINOs (Republican In Name Only).

Then came along Donald Trump, a true RINO — Trump was a registered Democrat for most of the last decade and has given money to Hillary Clinton, Harry Reid, Ted Kennedy and John Kerry — who has demonstrated the intellectual confusion that characterizes some on the right. I say that because as I and others have repeatedly pointed out, Mr. Trump has held left-wing views over the years on (among other things) health care, taxes, abortion, drugs, and immigration. He is no one’s idea of a limited government conservative, to the point of attacking those who want to reform entitlements programs (the sine qua non of rolling back the modern state).

But for those on the right who believe conservatism is synonymous with grievances, resentment, and rage — who don’t appear to want conservatism associated with a political philosophy or a governing agenda, but with attitude (the cruder the better) — Trump is the man of the hour. He’s insulting, erratic and conspiracy-minded. (He was the nation’s most prominent birther and believes “massive vaccinations” cause autism.) Most of all, for his well-wishers on the right like the radio talk show host Laura Ingraham, Trump is an “outsider” and “anti-establishment.” He knows how to “school” the establishment and has their “number.” What matters isn’t conservatism; what matters is someone who is as obsessively anti-establishment as they are — even if that someone has held liberal views that would be disqualifying in every other instance. (The irony and interesting psychological aspect of this is that those who claim to most hate the establishment are themselves pillars of it.)

Donald Trump won’t be the Republican nominee. But his candidacy will succeed to this extent: It will have exposed how little some on the right care about conservative ideas and how much they are devoted to political burlesque. They have every right to put on their show. But they don’t have the right to disfigure conservatism in the process.