Home / A. Sentience and moral status / Part DIR
"Human babies have the potential to be rational."
having the potential for something doesn't confer the rights of those who already have it. A future president doesn't command the army today. The argument also leaves out the humans who will never have that potential, and ignores that what demands protection now is present sentience, not future capacity.
Note: this chapter doesn't enter the abortion debate, where the same argument appears. The focus is the logical structure as applied to animals
Short answer
Potential doesn't transfer rights. As the philosopher Joel Feinberg wrote, a potential president of the United States is not on that account commander-in-chief. Potential capacity generates, at most, potential rights.
Besides, the argument doesn't cover all humans: someone with anencephaly, advanced dementia or in a permanent vegetative state doesn't have that potential, and remains protected. In other words, potential isn't doing the work. What protects any of them is the present capacity to feel.
For children
Can a boy who wants to be a pilot fly a plane today? No. He'll be able to when he grows up and learns. Being able to be something in the future isn't the same as being it now. And look: what stops us from hurting the baby isn't what they'll be one day. It's that they feel pain today. And the little pig feels it today too.
"And a person who will never have that potential? Do they lose protection? If not, what protects them?"
Como pode aparecer
"The baby grows into a grown-up, the pig grows into bacon."
"A child has a future, an animal doesn't."
"A cow will never be a doctor."
"Bad comparison: a baby becomes an adult, a chicken stays a chicken."
"Do you think a pig will ever write a book?"
"The potential to become a person confers moral status from the start."
"Killing a baby takes away a much bigger future than killing an animal."
"They're different trajectories; you can't compare them."
The strongest version
"The baby will grow up and think; the cow never will."
Strongest version (steelman):
- P1Having the potential to develop a morally relevant capacity confers, from now on, the status of those who already have it.
- P2Human babies have the potential to become rational and self-aware.
- P3No animal has that potential.
- CBabies have full moral status and animals don't.
The argument comes in after A1 fails: since babies aren't rational, it appeals to what they will be. It's the second attempt to keep babies in and animals out, A11 being the first.
There's a stronger version that speaks not of status but of harm: killing a baby deprives them of a whole future of experiences, and that future would be richer than an animal's. That version is dealt with in (d) and (e), and it leads straight to A16.
The argument is valid. Its soundness fails at P1, which commits the logical error pointed out by Joel Feinberg, and at P3, which treats "potential" selectively. P2 is true for most babies, but not for all, and that detail brings down the rest.
Full answer
- a
Reconstruction and diagnosis
The core of the problem is P1, and the classic diagnosis is Joel Feinberg's: potential capacity generates potential rights, not actual rights. A potential president of the United States is not, for that reason, commander-in-chief.
Case Potential Current status Medical student Will be a doctor Can't operate today 16-year-old Will be able to vote and, in many countries, drive at 18 Doesn't vote today Candidate May become president Commands nothing today Baby Will be rational Isn't rational today, and is protected anyway The last row is the decisive one. If the baby is protected now, and potential doesn't transfer status now, then the protection comes from something else. That something else is present sentience, which the baby has and the animal has too.
- b
Where the argument breaks
1. The logical error of potentiality.
From "X will be Y" it doesn't follow that "X now has the rights of Y". Otherwise every law student could try cases.
2. It doesn't cover all humans.
Anencephaly, advanced dementia and a permanent vegetative state are cases with no potential for future rationality. Since these humans remain protected, potential isn't the source of protection. The argument repeats the failure it was trying to fix, and species overlap returns.
3. Animals have potential too.
A piglet has the potential for a complex social life, bonds, exploring the environment and years of experiences. Whoever holds P3 has to say that only the potential for rationality counts, and explain why that specific capacity decides questions of pain and death. It's A1 again, now in the future tense.
4. The cut-off is arbitrary in another sense.
If potential matters, how far does it go? With technology, somatic cells can be reprogrammed, and animals can be genetically modified. The concept of potential doesn't carry a natural limit with it, and whoever uses it has to stipulate one, usually in the way that produces the desired result.
5. Present protection answers a present harm.
When someone feels pain, the harm is now. Talking about the future changes the subject: it turns a question about present suffering into a bet about biographies.
6. Confusing two debates.
The harm version (killing deprives of a future) isn't about moral status but about the gravity of death. It can support the claim that killing a human is worse than killing a fish, but not that killing a fish is permitted, nor that confining and mutilating are acceptable. That thread continues in A16.
- c
Data and sources
Source What it offers Note Feinberg, "Abortion" A potential president of the United States is not on that account commander-in-chief; potential qualification generates potential rights, not actual ones The text is about abortion, but the logical point is general, and that's what matters here Singer, Practical Ethics A potential X doesn't have the rights of an X Cambridge University Press McMahan, The Ethics of Killing (2002) The time-relative interest account: the gravity of death depends on how much the individual loses relative to the future they would have had Oxford University Press; basis of the harm version Naconecy, Ética e animais (2006) (in Portuguese) Systematizes the ways out of the argument from species overlap, potential among them This is a chapter about logic, not data. There's no relevant empirical controversy: no one doubts that human babies usually become rational adults, nor that some humans never will.
- d
The strongest counter-reply: it's not status, it's deprivation
The serious counter-reply abandons P1 and changes ground. It says: forget status, look at harm. Killing a healthy baby destroys decades of experiences, projects and relationships they would have had. Killing an animal destroys a real but less dense future. So the baby's death would be worse, and the difference would lie in the lost future, not in the species. This is Jeff McMahan's time-relative interest account, and it's the philosophically respectable version of A12.
- e
Why the counter-reply doesn't reach the conclusion
It already concedes the essential point.
It now compares lost futures, not species. On that ground, a six-month-old pig killed at slaughter loses years of life they would have had: the harm stops being zero and becomes large.
It grades death; it doesn't authorize killing.
That A's death is worse than B's doesn't make B's death permitted, much less in exchange for taste.
It says nothing about suffering.
Confinement, mutilations, separation from offspring and fear have nothing to do with a lost future. The counter-reply, even if accepted, leaves the entire critique of industrial farming intact.
It leads to conclusions the speaker rejects.
Taken seriously, the deprivation account implies that a young person's death is worse than an old person's, and that the death of a human with a short life expectancy would be less serious. Few accept these consequences without qualifications.
Potential can increase the duty, not dispense with it.
If the future a being would have matters, then cutting short the future of a young, healthy animal is exactly what farming does, billions of times a year.
Reasoning errors
Logical
Is the form valid?
The potentiality error
Proves too much
Selective criterion
Temporal shift
Epistemological
Does the evidence support it?
Concept without a defined limit
Moral
Is the criterion coherent?
Confusing gravity with permission
Silence about suffering
Biases
Psychological essentialism
Makes "potential" seem an essence already present in the individual
Medin and Ortony, 1989; Gelman, 2003
Narrative thinking
Human biographies are easy to imagine, and a pig's life is rarely narrated
The known identifiable victim effect
Motivated reasoning
The criterion shifts from present capacity to future capacity exactly when that saves the conclusion
General literature on motivated cognition
In-group bias
The relevant potential is always the typically human one
Motivated denial of mind
Imagining the animal's future would require recognizing their life as a life
Bastian et al., 2012; replicated by Jacobs et al., 2024
Extrapolations
The principle being tested is: "having the potential for a capacity already confers the rights of those who have it".
If it applied to…Rights that depend on capacityTap to see
Teenagers could drive and vote, students could operate on patients, candidates could govern. If potential transfers rights, it transfers all of them
This is Feinberg's logical point: potential generates, at most, potential rights
If it applied to…Humans with no potential for rationalityTap to see
They would lose protection. Someone with anencephaly, advanced dementia or in a permanent vegetative state won't have that capacity
They remain protected, which shows the real criterion is something else
If it applied to…Young animalsTap to see
They should be protected for the future they would lose. A piglet slaughtered at six months loses years of social and sensory life
Farming mostly kills young animals, which worsens the case by the argument's own criterion
If it applied to…An adult with few years left to liveTap to see
Their death would be less serious than a young person's, and their protection could be lower
Few accept this consequence without qualifications
If it applied to…Genetically modified animalsTap to see
If it were one day possible to give an animal human cognitive capacities, they would gain "potential" and change status, without anything in them changing today
Shows that the concept of potential has no boundary of its own and depends on stipulation
Contradictions
No one lets a teenager drive because they'll be a driver, or lets a student operate on patients because they'll be a surgeon.
People in a permanent vegetative state and with advanced dementia remain fully protected, which shows the protection comes from somewhere else.
The same person recognizes that a puppy "has its whole life ahead of it" when it's their own dog.
Farming slaughters animals long before the end of their lives: if the lost future matters, that's the worst possible case, not the most acceptable one.
In debates about the beginning of human life, many people reject the argument from potential; here, the same argument comes back as obvious.
What the argument gets right
What is true
Two things. First, the future really matters: part of what's bad about death lies in what it prevents from happening, and an ethics that ignored this would be poor. Second, there are real differences between biographies: a typical human life contains long-term projects, promises, unfinished work, and losing that is losing something specific.
But
The error lies in two steps. The first is logical: potential isn't actuality. The second is moral: recognizing that one death is worse than another doesn't make the second permitted. And since the argument itself puts the lost future at the center, it ends up condemning the practice it set out to defend, because farming lives off cutting futures short at the start.
Connections
Usually comes before
Usually comes after
Go deeper in Questão de Ética
Chapters from the open-access collection A Journey Through Animal Ethics that discuss this argument in more detail:
- Could Humans' Supposed Potential Justify Speciesism? Vol. I, ch. 5
References
Provisional author-date format. The links indicate the sources checked in writing this chapter.
Philosophy
- "Abortion", section on the logical point about potentiality.
- The Ethics of Killing. Oxford University Press.
- Ética e animais: um guia de argumentação filosófica (in Portuguese).
- Practical Ethics.
- Abortion and infanticide. Philosophy & Public Affairs, 2(1).
Psychology
- The moral standing of animals. *Journal of Personality and Social Psychology*, 116(6).
- The Essential Child; Psychological essentialism.
- Replication of Bastian et al. (2012). *International Review of Social Psychology*.