Superhero movies are often dismissed as teen adventure flicks writ large. But for my money, Marvel Studios has been downright daring in raising difficult, and very adult, moral dilemmas.

The Marvel Cinematic Universe’s latest entry, Avengers: Infinity War, raises a question familiar to hero stories — what is the worth of one life relative to many? — but avoids offering the usual easy answer. Instead, it asks audiences to sit with failure and doubt, in a way very few blockbusters do (and much more successfully than the recent Star Wars movie).

In doing so, it raises itself into the upper ranks of Marvel movies, maybe even of blockbusters generally. The more I’ve thought about it (and after seeing it twice), the more I like it.

But it also sets a bar that will be extremely difficult for 2019’s sequel to clear. The very intractability of the moral dilemma that’s been set up is going to tempt writers to cheap answers.

[Yes, this post is going to contain spoilers for Infinity War. You’ve been warned.]

The moral question of “trading lives” haunts the fight against Thanos

Early on, it becomes clear that Thanos has a few Infinity Stones, wants them all, and intends to wipe out half the living beings in the universe if he gets them. The stakes could scarcely be any higher or more clear.

One of the Infinity Stones is in Vision’s head. But when he suggests that Scarlet Witch destroy it, and likely kill him in the process, Captain America says, “We don’t trade lives.”

Within that one line of dialogue lies one of the oldest disputes in moral philosophy.

On one side, you have Captain America’s deontological perspective, typically associated with philosopher Immanuel Kant, which says (to, uh, simplify considerably) that every human being is an end in themselves, a basic moral unit due basic moral consideration, not a means to other ends. Kant said that you should act toward others only in a way that you would be willing to make a universal principle for all moral beings. You couldn’t make “sacrifice others for the greater good” a universal principle, lest everyone end up sacrificed.

On the other side, you have Thanos’s utilitarian perspective, typically associated with philosophers Jeremy Bentham and John Stuart Mill, which says that the goal should be the most good (happiness, well-being, utility, what have you) for the most people. The greater good, not the individual, is the primary moral consideration.

Both these positions can be made to seem ridiculous if taken to their logical extremes. Kant not only says you can’t kill one person to save two people, he says you can’t lie to one person to save two people. Contemporary philosopher Peter Singer has been outraging people for years by pushing utilitarianism to its limits, reaching conclusions many find abhorrent (like his position that it is justifiable to kill babies with severe disabilities).

But both positions also appeal to some of our intuitions. And their contrasting attractions are drawn with particular clarity in Infinity War.

Captain America won’t sacrifice lives; that’s all Thanos does

Thanos’s plan is fairly crude utilitarianism, but not so crude that it can be dismissed out of hand.

As World War II showed in the US, Japan, and Germany, the aftermath of a mass casualty event can be a period of sustained economic growth. If Thanos succeeds, there will be half as many people, but (once they recover from their shock and grief, presumably) they will have access to twice as many resources and will end up twice as happy. Their children will be happier too. Over the succeeding few generations, the total amount of well-being in the universe will increase relative to the no-Thanos baseline.

Of course, life being what it is, it would eventually overpopulate again and Thanos would have to do his thing again. But if he’s willing to cull every few centuries, he could theoretically achieve a gargantuan boost in net welfare over the fullness of time. He would be hated, but he would have produced more net utility than any being in history. He would be a utilitarian god!

Notably, nobody ever really argues with Thanos. When he lays out his plan to Gamora, she just replies, “You’re insane.” Well, but is he?

It’s not a question that troubles Steve Rogers. He cannot countenance the sacrifice of half of sentient life. A staunch Kantian, he can’t countenance the sacrifice of anyone. “We don’t trade lives.”

But that’s just the problem: He’s such a Kantian that he can’t sacrifice Vision, even though it would have saved countless Wakandan lives even before Thanos snapped his fingers. He can’t sacrifice anyone else, even when they want to be sacrificed, even when it would obviously help. (He can sacrifice himself — more on that later — but that’s a different moral calculus.)

This is a familiar tension in hero movies of all kinds: the dilemma of whether to sacrifice lives for the greater good.

Superheroes are typically Kantian, but they win anyway

Superheroes typically prize the individual life; that is said to be what makes them superheroes. That’s why fans were so outraged when Superman made the brutal utilitarian decision to snap General Zod’s neck at the end of Zack Snyder’s 2013 Man of Steel. Superman doesn’t kill; he’s a Kantian.

It is “antiheroes” who make those ugly decisions to sacrifice others, who are willing to be reviled to serve the greater good. One reason Batman has been so intriguing for so long is that he hovers unpredictably on that line between superhero and antihero. You never quite know how far he’s willing to go.

The problem is that if you set up the situation right, it can start to look pretty ridiculous to preserve the individual life at the cost of many lives. I mean, can anyone argue, as things currently stand, that Captain America made the right decisions? If he and his friends had destroyed the Mind Stone and killed Vision the second they learned about Thanos’s plan, they could potentially have saved billions, maybe trillions of lives.

Was Vision worth it? Actually, Vision died anyway. Was the principle of not trading lives worth it?

We’ve seen similar dilemmas in dozens of movies: the one for the many. It’s a great way to create narrative tension. Morally speaking, though, there’s not really a satisfactory resolution. Sacrificing the many rubs our utilitarian intuitions the wrong way. Sacrificing the individual rubs our Kantian intuitions — our sense of what a “superhero” is — the wrong way. Either way, there’s potential for disappointment.

That’s why the most common resolution to the dilemma is some last-minute narrative twist that allows the hero to save both the individual and the many, some clever (or often not-so-clever) way of avoiding the dilemma altogether.

Daring to let superheroes fail puts the Avengers sequel in a narrative corner

What’s remarkable about Infinity War is that there’s no last-minute twist, only failure. Steve Rogers and his friends make the typical heroic Kantian decision not to trade lives ... and it is a disaster. An unfathomable number of lives are lost. The movie ends with Captain America sitting on the ground, devastated, saying simply, “Oh, god.”

Movies rarely do that. Blockbuster superhero movies never do that. By cutting one giant story abruptly in two, ending after the conventional third-act crisis, the low point, Infinity War is able to do something genuinely novel in the superhero genre. And not with special effects — emotionally novel.

Still. Infinity War shows the Kantian approach failing spectacularly, but as many people have noted, it fails so spectacularly that it can’t be real. It’s got to be undone, if for no other reason than the people demand more T’Challa.

Directors Joe and Anthony Russo and screenwriters Christopher Markus and Stephen McFeely (who will all return for the 2019 sequel) have not escaped their narrative dilemma. They’ve only pushed it back. They made a great movie by leaning into it, making heroes suffer real consequences and failure as a result of their choices, but by doing so, they underscored it, highlighted it, and have millions of people around the world watching intensely for its resolution.

That sets an extremely high bar. It’s going to be difficult to clear it in a way that’s emotionally and morally satisfying.

The usual ways of resolving Kantian/utilitarian dilemmas

As I said, for writers trapped in a corner, the first resort is some sort of twist or scheme that allows the tough choice to be avoided — allows the hero to save the one and the many both, like when Spider-Man saves MJ and the falling bus full of children.

In the case of Infinity War, that will amount to someone getting ahold of the Infinity Gauntlet and reversing Thanos’s snap. The two-movie story will almost certainly culminate as such stories typically do, with the heroes triumphant, their foes defeated, and all their sacrifices (and avoided sacrifices) retroactively justified.

That can feel cheap, though, unless the twist through which the heroes escape the dilemma is truly clever, something that was planned and hinted at all along. Infinity War did drop a hint to that effect: Doctor Strange surveyed 14 million ways the future could unfold and saw only one in which the heroes win; he subsequently surrendered the Time Stone to Thanos.

However the heroes win, the path runs through Thanos finding all the stones and snapping his fingers. Perhaps Strange saw that the act somehow contains the seeds of its own reversal. Or perhaps he corrupted/ensorcelled the Time Stone in some way.

The other way to give that narrative twist some heft is self-sacrifice, which satisfies our Kantian instincts without running afoul of utilitarian consequences. Superheroes may not sacrifice another, even to save many, but they may sacrifice themselves, and all agree it is good. (Here’s a listicle of great acts of self-sacrifice in comic book movies. RIP, Groot.)

That’s what I’d bet on, were I a gambling man: There will be a way to reverse what Thanos did, but it will require one or more of the old-school Avengers — my guess is Cap and Tony, whose contracts are up — to sacrifice themselves. There’s a reason the original Avengers were the ones left behind by the snapocalypse.

The MCU is under serious pressure as it resolves this dilemma

In Infinity War, all the lofty talk of “not trading lives” was exposed as moral vanity, with disastrous consequences. The ones who refused to trade lives suffered death and loss; the one who traded lives got what he wanted. Utilitarianism in its crudest and cruelest form won out over Kantianism at its most noble.

It was a bold choice for the film to make. But it can’t stand. And backing out of it, without cheapening the whole thing, still holding on to a sense of consequence, will be an extraordinarily difficult narrative feat.

Marvel keeps raising the stakes, and it keeps executing. Now the stakes basically can’t get any higher, financially or emotionally. The 2019 Avengers sequel — the end of Marvel’s Phase Three and the launch of its Phase Four (god, I feel old) — will carry unbelievable weight. Even for some of us adults.