QuestionsDo animals matter as much as we do?Can they suffer? The only question that matters
Do animals matter as much as we do?Their suffering counts equally

Can they suffer? The only question that matters

"Can they suffer?"; sentience as the test; Bentham on animals

Jeremy Bentham 1748 · 1832The good is the greatest happiness of the greatest number: pleasures and pains can be calculated.
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What it claims

Animals' suffering counts morally, and neither law nor morality has any reason to let us torment them. Bentham does not conclude that their suffering counts exactly as much as ours: allowance must be made for the difference in sensibility.

Why

What counts morally is the capacity to suffer, not to reason or talk: many animals can suffer, as we do.

The same idea through history
Jeremy Bentham1789In the Introduction to the Principles of Morals and Legislation, morality aims at the greatest happiness of all beings capable of happiness. Chapter XVII counts animals among them, which the ancient jurists had degraded into the class of things. It is the principle of utility applied to animals.
Jeremy Bentham1789In a note to chapter XVII, he asks the question that became famous: not "Can they reason?" nor "Can they talk?", but "Can they suffer?". He compares the lot of animals to that of slaves, whom the law treated in the same way.
Peter Singer1974In "All Animals Are Equal", Singer quotes this passage in full and makes it the starting point of his critique of speciesism: the capacity to suffer is the only defensible boundary for counting a being's interests.
In short

"Can they suffer? The only question that matters" is an argument by Jeremy Bentham (Bentham, An Introduction to the Principles of Morals and Legislation (1789), ch. XVII, § 4, note, 1789) on the question "Do animals matter as much as we do?" (answer: their suffering counts equally). Its claim: Animals' suffering counts morally, and neither law nor morality has any reason to let us torment them. Bentham does not conclude that their suffering counts exactly as much as ours: allowance must be made for the difference in sensibility. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P1, P5). AskPhilosophy presents 3 objections, 3 of them with a documented reply, and the original text behind each premise, checked word for word.

Bentham, An Introduction to the Principles of Morals and Legislation (1789), ch. XVII, § 4, note
Valid with an implicit premise

In the eighteenth century, the law treats animals as things: one may do what one likes with them. Jeremy Bentham, an English legal thinker, asks a question hardly anyone was asking. Why should these beings not count? The usual answer: because they cannot reason, because they cannot talk. Bentham says this is the wrong question. A full-grown horse or dog reasons and converses far better than a baby a few days old, and nobody concludes that the baby may be tormented. The question is: can they suffer? If so, their suffering is a reason to act or to refrain, as ours is. He adds, with a caution people often forget, that this does not mean animals are our equals in everything, nor that we may never eat them: what cannot be justified is tormenting them.

P1 · implicit premiseMany animals can suffer: they are sentient beings, capable of pain and pleasure.
P2What decides whether a being counts morally is its capacity to suffer, not its capacity to reason or to talk: a being that suffers has an interest in not suffering, and that interest is a reason.
P3Reason and speech cannot be the dividing line: a full-grown horse or dog is far more rational and conversable than an infant, and yet we do not treat the infant's suffering as negligible.
P4Differences of body, such as skin colour, hairiness or the number of legs, are not sufficient reasons to abandon a sensitive being to the caprice of those who torment it. This has already been recognised for the skin colour of humans.
P5 · implicit premiseThere is no other difference that justifies not counting animals' suffering. Bentham asks: "What else is it that should trace the insuperable line?" and sees no answer.
So animals' suffering counts morally, and neither law nor morality has any reason to let us torment them. Bentham does not conclude that their suffering counts exactly as much as ours: allowance must be made for the difference in sensibility.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P5, the computer finds a world where animals suffer and neither reason, nor speech, nor body justifies setting them aside, but where another difference (for example belonging to the human species, or having a soul) is judged relevant: their suffering would not count.
Valid with P1 and P5. P2 says a sentient being counts unless a relevant difference (reason, speech, body or anything else) can set it aside. P3 and P4 rule out reason, speech and body. P5 rules out any other difference, and P1 says animals are sentient.
Analogy.

Objections

3

Each objection is a conversation: click to see who replies and where the debate stands.

Immanuel Kant 1797 · attacks the conclusion

Summary: for Kant, only rational beings, able to give themselves a moral law, are ends in themselves. Animals are not: we have no duties to them, only duties concerning them. Being cruel to an animal is wrong because it smothers in us the compassion that helps us treat humans well. Its suffering, then, grounds no direct duty.

a defender replies
see the argument
We have not yet found a direct reply by Bentham in the texts.
Peter Singer defender of the argument · 1974
If direct duties are reserved for rational beings, some humans are left out: a baby, or an adult with severe brain damage, is no more rational than an adult mammal. Singer sees no capacity that human infants have and adult mammals lack to the same or a higher degree. If we refuse to exclude those humans, we must also count animals.
C
Carl Cohen 1986
Cohen answers that reason is not a test given to each human being one by one. It is a trait of the kind: a human being is of a kind capable of moral judgement, even when a given individual lacks it through disability. "The issue is one of kind." What disabled humans have retained, animals have never had.
Where the debate stands (our summary)Our summary: the disagreement is about what makes a being the object of direct duties, the individual's own capacity (Singer) or the nature of its kind (Cohen, in Kant's line). Each camp charges the other with inconsistency: one leaves some humans out, the other judges an individual by its kind's average. An open point.
René Descartes 1637 · attacks premise 1

For Descartes, animals have no mind: it is nature that acts in them according to the disposition of their organs, like a clock that tells the hour without knowing anything about time. Their cries and gestures do not prove that they feel anything. If they are machines, Bentham's question, "Can they suffer?", gets the answer no.

a defender replies
see the argument
No reply possible: objection raised in 1637, after the author's death (1832).
T
The Cambridge Declaration on Consciousness defender of the argument · 2012
A group of neuroscientists gathered in Cambridge declares that non-human animals have the neural substrates of conscious states. In their words, humans are not unique in possessing what generates consciousness: this holds for all mammals and birds and for other creatures such as octopuses. This is not proof in the strict sense, but the hypothesis of a machine without feeling is much weakened.
Peter Carruthers 1989
Summary: Carruthers grants that animals perceive and have mental states, but holds that their experiences are not conscious in the strong sense: there is nothing it is like to be them, at least not as there is something it is like to be us. Their pain would then not be felt suffering. Evidence about brains does not settle this question of principle.
Where the debate stands (our summary)Our summary: hardly anyone today defends the animal-machine thesis for mammals and birds, but the basic disagreement remains over what it takes for a pain to be lived, and over what evidence about the brain can establish.
Jeremy Bentham himself 1789 · attacks the conclusion

In the same note Bentham writes that if being eaten were all, we have very good reason to eat those we like to eat: we are the better for it, and they are never the worse. They have none of our long anticipations of misery, and their death at our hands is often quicker than the one nature has in store. His question "Can they suffer?" does not, by itself, condemn painlessly killing animals to eat them.

a defender replies
No reply possible: objection raised in 1789, after the author's death (1832).
Peter Singer defender of the argument · 1974
Singer follows Bentham here: the suffering we inflict on living animals shows our speciesism perhaps even more clearly than the fact that we kill them. He also notes that one might argue that part of what is wrong with killing a human is that humans have plans and desires reaching into the future. The argument therefore bears first on suffering.
Tom Regan 2004
Regan refuses to stop at suffering. For him, using animals for fashion, research, entertainment or the pleasure of eating treats them as resources, and this violates their right to respect even if their welfare is looked after. Reform is not enough, for example by raising only "happy" cows: "abolition is required".
Where the debate stands (our summary)Our summary: this is the basic disagreement among defenders of animals. For Bentham and Singer, what is wrong is chiefly suffering, so a farm without suffering would be less serious. For Regan, the wrong is treating the animal as a means, so only abolition will do.
What today's voices say
Defend it
Peter SingerHe takes Bentham's test, the capacity to suffer, as the basis of animals' moral standing.