Photo: Jane Flavell Collins/epa/Corbis

When I saw that Dzhokhar Tsarnaev had been sentenced to death, a cold, queasy feeling settled in my gut, and I got very sad. From a certain perspective, this doesn’t make much sense — Tsarnaev murdered people in cold blood, and if anyone deserves the death penalty, it’s him. And yet I couldn’t — can’t — shake the feeling that the U.S. government is going to commit a barbaric wrong. And I’m far from the only Bostonian who feels this way — most of us don’t want to kill Tsarnaev.

Between now and the execution (assuming it occurs), at dinner tables and bars and anywhere else people gather to argue, there will be endless debates over both the righteousness of capital punishment in general and whether it should be administered in this particular case. But these debates will go nowhere, because this is, at its base level, a gut issue, one of the best examples of how some of our political beliefs come not from lofty reason and careful weighing of evidence, but from impulses we can never fully understand or explain.

To see what I mean, try not to get too emotionally caught up in the next death-penalty argument you have, whatever your views. Instead, zoom out a bit; track where the debate goes. You’ll inevitably find that the debate splinters into a number of sub-debates. And most of these sub-debates end up veering into the realm of instinct.

This gut-centric view of political psychology isn’t a new idea — researchers like Jonathan Haidt have been doing fascinating work that argues, at its core, that people don’t weigh evidence and then decide where they stand on an issue. Instead, moral impulses embedded deeply within them — impulses that vary widely across exactly the political divisions you’d expect — stack the deck beforehand. To Haidt and other researchers, the stories we tell ourselves and others about why we believe what we believe are mostly window dressing, forms of ex post facto justification for decisions really made at a baser level.

Take my own arguments, for example: I happen to think Tsarnaev wasn’t fully morally responsible for his act, given his age and the pernicious influence his older brother wielded over him. I also don’t think killing him will relieve the suffering of his victims — or, at least, that it won’t do so any more than letting him rot in a Supermax. I also think there’s a chance that someone, somewhere will be inspired by his “martyrdom” — America is killing yet another Muslim! — to do something terrible. Finally, I think that even if I felt differently on all of these points, it wouldn’t change the fact that flaws in the legal system, including cases in which states appear to have executed innocent people, suggest the death penalty should be abolished.

What all these arguments have in common is that they’re more or less dead ends for compromise and understanding. I can’t pull data for you showing that Tsarnaev (or anyone) isn’t morally responsible, or that there’s no net gain in happiness and consolation from killing him. There isn’t a study that can prove the martyrdom threat is an actual one. And people who support the death penalty can easily say that it should be reformed, not abolished. It’s very hard to prove any of these points in a meaningful way, in other words.

And, sure enough, people are already starting to make the exact opposite points. There are people for whom it’s beyond obvious that Tsarnaev was morally responsible for what he did, that it will help society heal to kill him, that the terrorists out there want to kill us anyway, regardless of whether or not they have a martyr figure to fire them up. Debate won’t sway them, just like it won’t sway me.

That doesn’t mean our gut-level responses should dictate these issues to the extent that they do, of course — one can try to figure out whether introducing the death penalty serves as a deterrent (though doing so involves pulling a tiny signal out of an ocean of noise), or use brain-imaging to learn more about impulsive behavior in young people (though there’s a pretty wide gap between observing a neural pattern and making simple claims about moral culpability), and then act accordingly. But by now there’s a huge amount of evidence that people don’t really change their minds in response to evidence, or not usually at least. When people feel their gut beliefs getting attacked, in fact, the opposite often occurs: If anything, they’re more likely to harden their position.

Where does this leave us on Tsarnaev? With a depressing gulf. It’s sad to me that people will never be able to understand exactly why I feel so strongly about this; it’s also sad to me, in a less visceral way, that I’ll never be able to walk around in the heads (or guts?) of people who strongly want him put to death, or who oppose gay marriage, or who are ardent libertarians. That’s the problem with being such a gut-centric species — minds can be changed, but guts are less malleable.