Olsen: Bannon’s economic populism really consists of two things: restrict trade and restrict immigration. That’s got loads of problems, not the last of which is that trade helps many workers, too. And it takes the business-conservative faction inside the G.O.P. head on without sufficient support from the broader Tea Party wing, at least on trade. So he was always going to have a terrible time on that unless Trump was willing to tell aides who don’t agree with him to just do something specific that Trump probably doesn’t know enough to describe. The G.O.P. will become a workers’ party only when enough people within it see both the justice and the necessity of it becoming so — and that is still a ways off.

Douthat: But Bannon did fight a bunch of battles on your territory, Dan — taking the less interventionist line on a range of issues, from Syria to Afghanistan to maybe North Korea. And he lost most of those battles, not to the ideological neoconservative types, but mostly just to Trump’s generals. So we’ve ended up with a foreign policy in which the generals are the custodians of the foreign policy status quo, right?

McCarthy: You’re right that Bannon is serious about policy, Ross, in his way. When it comes to blurring the line, I should emphasize I don’t mean that Bannonism is “fake politics.” It’s real, but it’s radically different from the politics we’re used to. It’s a new hybrid: a media-political entity. Democrats thought that Ronald Reagan was such a thing, but this time it’s come true. As for the generals, they’re not advancing a grand ideological program in foreign policy, although they may be loyal to the ghost of one simply by force of inertia. They’re keeping up a degree of surface continuity, but the foundations of our policy have been called into question. You’re right that that’s not enough, but it’s where deep change has to start.

Douthat: O.K. — but then who follows it through? Trump is president, we assume, for another three years, and then he (presumably) will run for re-election. As long as he’s bestriding the Republican world, it seems that no G.O.P. politician is going to emerge as a clear champion of the next Republicanism, whatever it might be. Or maybe that’s wrong. But it seems to me that he has only a few figures right now who are even would-be heirs — Tom Cotton certainly (whose foreign policy views I suspect you strongly dislike, Dan) and maybe even Ivanka Trump, depending on her ambitions, but beyond them nobody obvious at all.

Olsen: True, but it takes only one to start something. Fear, and a lack of policy-specific work in a host of specific areas, are the major things holding back the next iteration of conservatism, and fear is by far the largest. Once pols start taking the leap, however, and see they get cheers from voters, the numbers will start to swell. The fact is there are very few Republican voters who really care about the issues the party’s donors and the Wall Street Journal editorial board are pushing. Had any establishment Republican — say, Scott Walker or John Kasich — been willing to explore these themes, they would have pre-empted Trump and the rest of the field. There is a large market for a conservative-populist party, which is exactly what Reagan tried to create during his lifetime.

McCarthy: What Trump has done is to re-politicize basic questions of policy, including foreign policy, that for a long time had been the domain of a narrow range of expert opinion. When it comes to who follows through, I don’t think we should be looking for a single figure, we should be looking rather for a national discussion, a political discussion, throughout our institutions. There’s no blueprint, as some of my realist friends in the academy sometimes seem to believe, that can be smoothly applied to create a new foreign policy. There has to be political give and take — ”political” in the broad sense, in the media as well as in Congress, and among the public. Once Trump no longer personally bestrides the Republican scene, there will be a whole host of squirming and wriggling new mutations evolving their way out of the new environment — I just couldn’t guess what’ll they look like when they’ve all grown up.

Douthat: But do you worry at all, Dan (and this goes for you too, Henry), that if Trump is perceived as a crashing failure — or for that matter if he’s somehow ejected from office — that the ideas that you think he’s tacitly championed will be seen as inherently tainted and discredited as well, even or especially among the people who might otherwise be interested in taking them up, in having the kind of conversation you envision?