For more than one month now, the Republican presidential contest has been a virtual forum for a debate about the extent to which U.S. security policy should be rooted in suspicion of foreign and domestic Muslims.

That debate has been defined by a strong consensus among most candidates not named Donald Trump that domestic Muslims deserve extraordinary scrutiny, and that Muslims seeking refuge from civil war should be directed elsewhere—but that Trump’s slightly more aggressive proposal to suspend all Muslim in-migration to the U.S. is somehow excessive. (By what principle is freezing settlement of Muslim refugees prudent, but freezing Muslim immigration altogether is not? They do not say.) 

Trump may be technically isolated, but he’s thrived in isolation. He set the debate on these terms for a reason. And it is appropriate in a way that a party caught in the grip of xenophobic panic should face extended scrutiny for its increasingly hostile, exclusionary views.

Yet this debate over Muslim immigrants and citizens—much like the larger, Trump-driven debate over U.S. immigration policy that preceded it—has, in its smothering enormity and persistence, done the public (and the candidates themselves) a disservice.

There is value, of course, in assessing the merits and feasibility of deporting 11 million undocumented immigrants against the non-Trump candidates’ counteroffer of leaving those immigrants in the shadows indefinitely. It’s also important to assert the view that Trump-esque hostility to outsiders is in line with the country’s worst traditions. But these arguments have frozen a world’s worth of news and substance out of its appropriate place in this campaign. It would be to everyone’s benefit if the candidates were pulled back into that world during the second CNN primary debate on Tuesday. Alas, that is probably expecting too much.

The Republican contest in 2012 was in no way characterized by high-mindedness, but it’s worth remembering that at this point in the cycle four years ago, the field had dedicated weeks and weeks to a substantive (if not entirely honest) debate over the merits of their tax plans. These plans ranged from outlandishly regressive and dishonestly described proposals like Mitt Romney’s huge, uniform reduction of every income bracket, to widely mocked, cruel proposals like Herman Cain’s tortured national sales tax (9-9-9) and Michele Bachmann’s call for poor people with negative liability to have their refunds eliminated and be required to pay at least one dollar in net tax every year.

At the time, the candidates were disgruntled by the extended focus on and skepticism of their tax plans. But as we’re learning by watching this year’s race, things could’ve been much worse. By contrast to 2012, the 2016 candidates’ tax plans have come in for little scrutiny, despite the fact that by most measures they are far more irresponsible. According to the Tax Policy Center, which kept the tax debate relatively well moored in 2011 and 2012, Jeb Bush’s tax plan would increase increase deficits by $6.8 trillion over its first decade. Trump’s plan is a more irresponsible version of Bush’s. Marco Rubio’s plan is too vague to even score, but is more profligate than Bush’s and, according to one left-of-center analysis, would reduce federal revenue by almost $12 trillion within a decade. Ted Cruz’s plan, while perhaps less fiscally irresponsible, would, by pairing a flat tax with a value-added tax, be dramatically more regressive.

Meanwhile, Republicans briefly decompressed from their Trump-related stress this weekend to mock and decry the global climate change agreement, struck between 196 countries in Paris on Saturday, as flimsy and unlikely to hold. The incoherent consensus within the party is that the climate deal will never stop global warming, which probably isn’t real anyhow. Outside of its closed information ecosystem, the political upshot of the Paris agreement was to throw the GOP’s uniqueness—as the only major political party in the world to reject both solutions to climate change and the science underlying it—into stark relief.

If moderators were to ask the candidates to grapple with that dishonorable distinction, or to explain how they would go about extracting the United States from the agreement, they would inject more realism into the debate than they ever will if they allow Trump to set the terms. And they would be doing the Republican party—especially the eventual nominee—a great favor. By virtue of the fact that it will include a Democrat, the general election debate will not be confined to right-wing fever swamps. Candidates will have to grapple with the fact that their policies will have stakeholders outside the conservative voting base, and even in other countries. 

If Trump loses the nomination, the winning candidate will be hampered by the extent to which he has debased the primary campaign. The sooner the Republicans break out of this cycle, the better off they will be. Tuesday night is one of their last decent opportunities to do so.