Wednesday, June 10, 2026

When utilitarianism turns monstrous: The Pope vs. Peter Singer

On May 25, Pope Leo XIV released his first encyclical, Magnifica Humanitas, a long meditation on how to protect the human person in the age of artificial intelligence. Its central conviction is that human beings possess a dignity that does not depend on what they can do, a worth that holds whether a person is brilliant or impaired, productive or helpless, and that this dignity is precisely what the new technologies threaten to erode. The document warns against a culture that measures people by output and against the transhumanist dream of editing humanity into something it considers an upgrade. Against all of it the Pope sets a single insistence, that being human is itself the ground of a worth no machine can claim and no circumstance can revoke.

Peter Singer disagreed. Singer is the Princeton philosopher who, more than any living thinker, made the modern case for utilitarian bioethics, the view that the right act is the one that produces the most good measured across everyone affected, and that questions of life and death should be settled by that calculation rather than by tradition or sentiment. He is best known for Animal Liberation, the book that launched the modern animal rights movement by arguing that the capacity to suffer, and nothing else, determines whether a creature's interests count. Applied to the encyclical, his position is exactly what you would expect. Human dignity, in his view, is a piece of unearned favoritism. What matters is not whether a being belongs to our species but whether it has the mental capacities, above all the capacity to suffer and to want, that give a life its value. Being human, for Singer, is morally irrelevant.

The premise leads somewhere terrible. Singer defines a "person" as a being that is self-aware, that understands itself as existing through time, that holds preferences about its own future. An infant has none of these. Neither does an anencephalic baby, born without the brain structures that thought requires, nor a patient in a deep and irreversible coma. From this Singer draws the conclusion his critics quote with disbelief, that the life of a newborn is of less value than the life of a pig, a dog, or a chimpanzee, and that the painless killing of a severely disabled infant can be morally permissible. When Princeton appointed him in 1999, activists for the disabled protested that very view.

Most people who locate moral worth in mental capacity quietly stop applying the rule the moment it threatens a human being they love. They invoke intelligence to elevate humans over animals, then fall silent when reminded that a grown dog out-reasons a newborn. Singer took the capacity criterion that the Western tradition had always applied with a thumb on the scale and he applied it honestly in every direction, letting the clever animal in and letting the incapable human fall out. His monstrous conclusion is not the product of bad logic. It is the product of good logic resting on a false foundation, which is the more dangerous thing, because a philosophy is never redeemed by its internal consistency. When flawless reasoning arrives at the disposability of the most defenseless human beings, the consistency stops being a defense and becomes the diagnosis.

The criterion Singer trusts in determining the value of a being has a history, and the history is a record of one question receiving a series of failing answers. The question is old and constant: "What makes human beings different from the animals?" For most of the Western tradition the answer was reason. Aristotle's human was the rational animal, and the rational soul was the thing the beasts lacked, which conveniently set humanity on one side of the line and everything else on the other.

The word "consciousness" entered the argument as a newer and more sophisticated answer to that same old question. It did not exist as a term of art until the Cambridge Platonist Ralph Cudworth coined it in 1678, translating a Greek word of Plotinus, and he coined it expressly to attack the materialism of Thomas Hobbes, treating consciousness as something immaterial that mere matter could not produce. John Locke then built it into the foundation of the self, defining personal identity as a thread of continuous self-awareness, the mind's presence to itself across time. The very word was machined out of conscientia, the Latin root of "conscience," a term about moral standing and the soul's knowledge of right, and it carried that moral freight into its new life. Consciousness was not a neutral discovery about minds that later got drafted into moral service. It was forged, by men defending the immaterial soul against materialism, as a fresh way to mark the human as a being apart.

The new answer failed the same way the old one had, because the boundary kept moving every time someone made a new discovery about animals. Tool use was ours until the crows used tools. Language was ours until the apes began to sign. Self-recognition in a mirror was ours until elephants and magpies passed the test. Each retreat carried the boundary to a new faculty, and each new faculty failed in turn, which is the signature of a definition tracking a conclusion fixed in advance rather than a fact discovered in the world.

The deepest break came in 1789, in a single footnote in Jeremy Bentham's Introduction to the Principles of Morals and Legislation. Bentham asked what could possibly trace the insuperable line between the beings that count and the beings that do not, considered reason and speech as candidates, and threw both out saying that the question is not whether they can reason, nor whether they can talk, but whether they can suffer. He justified the switch with the very counterexample that breaks the old criterion at the human margin, observing that a full-grown horse or dog is more rational and more conversable than a human infant of a day or a week or a month old. The rationality standard was abandoned because it failed to protect the newborn, and the capacity to suffer was installed in its place.

Bentham meant this generously. He set his argument beside the abolitionist cause, holding that the number of a creature's legs or the texture of its skin are as poor a reason to abandon a sensitive being to a tormentor as the color of a man's skin had been, and he looked forward to the day humanity would extend its protection over everything that breathes. The switch from reason to suffering widened the circle, and for animals it genuinely did. What Bentham never pressed was the edge hidden inside his own move, because a criterion that admits beings according to a capacity must, if it is honest, expel the beings who lack that capacity. Bentham flinched from that edge, which is why his marginal case is always the infant who will grow into reason, drawn with sympathy. Singer does not flinch. He inherited Bentham's criterion and ran it in the direction Bentham declined to look, and the contracting edge did its work on the newborn, the disabled infant, the comatose patient. The same blade that widened the mantle to cover the animal cut the most vulnerable humans out from under it.

Stand back from the whole receding history and it confesses something its participants never admitted. The concept of consciousness, in its long career as the mark of the morally significant, was built to answer the question of what makes human beings different. It kept failing at that job, so it kept being redefined, until it arrived at a form that can no longer be checked at all. Philosopher David Chalmers named the "hard problem of consciousness," the observation that subjective experience, the inner feel of pain or the redness of red, cannot be derived from any description of the brain's machinery, however complete. The inner fact is real and it is sealed off from outside verification. An ethics that grounds moral standing in that inner fact has therefore built its foundation on the one thing no observer can ever confirm. Singer's confident rankings of who suffers and how much are confident readings of behavior standing in for an interior he cannot reach and cannot possibly know. This is the same proxy game every earlier fence-builder played, now speaking the vocabulary of cognitive science.

The error was never which faculty to choose. The error was treating the faculty as the answer when it was only ever a guess at the answer. Consciousness was the wrong reply to the right question, and because the reply was wrong, a brilliant mind could fixate on the consciousness and lose the humanity entirely. Singer is the result of that mistake.

We need to reframe the question that started this whole thing: what makes a human unique, different from animals and from AI?

Mental capacity is not the answer. The anencephalic baby is undoubtedly human. Yet she will never think, never suffer in a way she can register, and never form a preference about her own future. By every capacity test ever devised she fails, and the Pope is still right that she carries inherent dignity, because her worth was never housed in a faculty.

But the Pope didn't define what makes a human unique, either.

A human being is a member of a a covenantal community, a web of relationships and obligations. The anencephalic baby still is part of that web even if she can only take and not give. Moreover, a human being has a single finite life that cannot be copied, backed up, restored, or replaced, which is what makes it always more valuable than an AI or a robot.

When an ant dies mid-task another ant fills the gap and the colony never notices. When an artificial intelligence is deleted it can be restored from a saved copy, identical, with nothing lost that a backup cannot return. A human being has no backup, and the relationships she anchors collapse into absence when she is gone, with no replacement able to reconstitute them. Worth lives there, in the non-fungible place inside a relational structure, and not in the thinking or the feeling that the structure happens to support in those of us equipped for it.

A dog may be beloved, and part of a web of relationships, but as a species it cannot be considered part of a covenant. That doesn't mean that a dog is not respected and that its life is not meaningful, but it is never as valuable to humans as other humans are. There is no obligation for a dog to save another dog's life, even though it might do so. Even service dogs may be trained to act that way but it is not an obligation. But there is such an obligation for humans.

The worst humans get trials precisely because they are part of the covenant. An animal that kills a human is put down without that presumption.

Singer might object that the distinction is arbitrary. But noticing that people aren't dogs or chimpanzees is not arbitrary. Our obligations are first to family, then community, country, and mankind, and only then to pets. Singer rejects that, but this is how people naturally act. Obligations come from relationships, and relationships cannot be waved away. A father who chooses to save the lives of others and let his children die is not acting as a father and is not fulfilling his obligations. Singer flattens all relationships to a single value, and the end result is horrific. Trivializing all relationships — marriage, motherhood, comrade in arms — is not serious ethics.

The reframing also dissolves the puzzle Singer leans on. We can never confirm that another's pain matches our own, and we never needed to. The human brain is built for language, empathy, and social coordination because reading other minds well enough to act decently toward them is how social creatures build something against the universe's general slide into disorder. The model in my head of your suffering does not have to be metaphysically exact. It has to be close enough to let me respond, cooperate, and refrain from harming you, and close enough is the whole specification. This is engineering, where a tolerance that works is the goal, against physics, where the exact value is the goal. Ethics has always run on the engineering tolerance. Singer mistook it for a physics problem and built a moral order on a quantity no instrument can measure.

Consistency is a virtue, and Singer has it in abundance. But it is one virtue among many, and not even among the most important ones. It ranks far below the protection of human dignity, which his consistency dismantles. A single axiom applied with doctrinal rigor and held immune to the counterexamples that ought to falsify it is not the profile of a science but the profile of a faith, and the faith Singer keeps does not describe how the world works or how human beings actually reason about the people in front of them. He can sketch a future in which persons are interchangeable and the incapable are surplus, but it is not a world anyone wants to wake into, least of all the vulnerable people whose lives his thought experiments quietly spend. The stated aim of his tradition is to enlarge human happiness, and the destination he reaches is a permission to kill the helpless. To call that ethics mocks the word. It is a thought experiment that escaped the seminar room and went looking for real people to endanger, and the right response is to send it back and ask the question again, correctly this time.

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