A provocative what-if — actually, two provocative what-ifs — from Jonathan Last.

Obama voters: If you could go back to 2012, knowing what you know now, would you still vote for Obama?

Because we now know that the timeline created by Obama’s 2012 election meant handing unified control of government to a Republican party with Donald Trump as president. So net-net, would you rather have had Mitt Romney as president and the Republican party kept in a moderate place? Or would you still take an extra four years of Obama, even though it means getting Trump?

Trump voters: If Bernie Sanders is elected president and he is given unified Democratic control of Congress (which is what he’ll likely have if he were to win), will the Trump presidency still have been worth it? Net-net, would you rather have had Hillary Clinton constrained by a Republican Congress in 2017? Or would you still take four years of Trump, even though it means handing the country over to a socialist?

If we could poll this, I’d guess that something like 75 percent of Obama voters would reaffirm their 2012 vote for him whereas 95 percent of Trump voters would reaffirm their 2016 vote for him. Not because Trump fans are so much more devoted than Obama fans but because of the sunk-cost fallacy. Obama voters have had their commitment to O severed by his passage from the political scene so they don’t feel the same pressure to protect their emotional “investment” in him as Trump voters do with a sitting president. If in fact we do end up with President Bernie, some of the Trumpers who claim today that they’re okay with a Sanders presidency as the inevitable result of a Trump presidency will say otherwise a few years from now when they’re getting a snoutful of socialism daily.

Last is making a point about the old canard that elections are binary choices. There’s Trump and there’s Hillary, we were told in 2016; however much you dislike the former, the only alternative is the latter. That’s technically true but largely false, counters Last. If it was a foreseeable consequence that the left would further radicalize as a result of a Trump victory, then the choice in 2016 was more like Trump or Hillary plus an increased probability of a far-left nominee in 2020 plus an even greater probability of a far-left nominee in 2024 if Trump wins a second term and Democrats go insane from their rage. There are more than two variables to the alleged “binary choice.” If you elect a candidate strongly favored by, and inclined to pander to, his own party’s base you need to account for the fact that the other party is likely to respond in kind in future election. If in fact Trumpism ends up making socialism a viable electoral force in national elections, would we have been better off with Marco Rubio, say, as nominee in 2016?

I’m a fatalist so I tend to cope with arguments like that by retreating into the assumption that the two party’s bases will find excuses to radicalize no matter what’s actually going on in politics. For instance, if Last got his wish and Democrats agreed that we should go back in time and make Romney president in 2012, would the Republican Party’s trend towards reactionary populism have been stopped? It would have slowed down for sure: The impulse to back the president on everything he does would have made some of the people we know today as Trump loyalists into Romney loyalists. Sean Hannity would have been a stalwart advocate for Romney’s policies on Fox every night for the past seven years. Certainly the GOP under Romney would be less populist right now than it is under Trump.

But what about five years from now?

Last wants us to look at longer time horizons so let’s look. Imagine that Romney was facing the same sort of circumstances at the border that Trump is right now — no wall, a huge crush of illegals seeking entry in the guise of asylum claims. How would the right-wing populists who worship Trump feel about that? My guess is they’d cite it as the inevitable failures of a weak establishmentarian from the business class who’s not nearly as concerned about illegal immigration as he pretends to be. What we need is a politically incorrect authoritarian, they’d say, a guy who sounds like Donald Trump does when he calls into “Fox & Friends” every Friday morning. Meanwhile, it’s anyone’s guess what Romney’s white-collar pedigree and free-trade policies would have done to affect the Democrats’ drift towards democratic socialism. Would it have given Bernie Sanders extra traction against Hillary in 2016? If not, would Hillary have lost to the incumbent Romney (incumbents are famously hard to beat), further convincing socialists that centrist liberalism is a dead force nationally? What would Romney’s racial legacy have been as the patrician traditionalist from a very white state who ousted the first black president in 2012?

Neither lefties nor righties would have abandoned their efforts to radicalize their parties just because the president was different. Their tactics would have differed dramatically and the time horizons would have differed to some extent but I’m not so sure that the odds of Trump delivering us a Bernie Sanders presidency are necessarily greater than the odds of Romney delivering us a Bernie Sanders presidency. Just like I’m not so sure that it’s not the financial crisis, rather than partisan backlashes to Obama and Trump, that have gifted us with a raft of suddenly viable radical populist politicians.

I think the strongest argument for Last’s position is that an outside presidency like Trump’s has changed people’s perceptions of what’s possible in national elections in ways that having Romney or Hillary in charge simply wouldn’t have. With Romney and/or Hillary as president you’d have people in each side’s base convinced to their chagrin that American politics at the highest level really is limited to a narrow centrist-y ideological band. You can’t be a game-show host chattering excitedly about a “Muslim ban” and expect to get elected in America. We choose our leaders from the same pool of technocratic elites. With Trump’s victory, that’s out the window. Anyone can be president now — the geriatric socialist Bernie, Alexandria Ocasio-Cortez, anyone. Even in this scenario, where there’s no Trump, I think the Overton window would have moved eventually for other reasons, like hyper-polarization in the age of the Internet and 24/7 news. But certainly Trump hastened its movement. That’s the real extra-binary choice in presidential elections: “Do you want the Republican or the Democrat, and do you want many more American voters open to radical possibilities for leading the country going forward?”