Animal Ethics

Bentham's question

In a 1789 footnote that nobody read for nearly two hundred years, Jeremy Bentham proposed the criterion that would eventually reorganise the field. After observing that French law had recently extended legal protection to enslaved persons of colour, he wrote: "The day may come when the rest of the animal creation may acquire those rights which never could have been withholden from them but by the hand of tyranny… The question is not, Can they reason? nor, Can they talk? but, Can they suffer?"

The Cartesian view dominant before Bentham — that animals are unfeeling automata, machines made of meat — has been comprehensively retired by neuroscience. The 2012 Cambridge Declaration on Consciousness, signed by leading neuroscientists at a conference attended by Stephen Hawking, affirmed that all mammals, birds, and many other species "possess the neurological substrates that generate consciousness." The empirical question Bentham raised has an answer: yes, they can suffer. The remaining question is what that fact morally requires.

Peter Singer and Animal Liberation

The book that detonated the field was Animal Liberation, published in 1975 by an Australian philosopher then at NYU. Singer's argument is structurally simple. The principle of equal consideration of interests — central to all serious ethical theories — requires that like interests be weighed alike, regardless of who has them. The interest in not suffering is a like interest. Therefore, weighing a human's pain more heavily than an animal's pain just because the sufferer is human is a bare prejudice. Richard Ryder had named this prejudice speciesism in 1970; Singer made the term famous.

The empirical sections of Animal Liberation documented in unsparing detail what factory farming and laboratory research do to animals. Singer's claim was not that animals matter equally in every respect — he agreed that you may rescue a drowning child before a drowning dog because the child has a richer set of interests — but that like interests must be counted alike. By that standard, an industry that confines hundreds of millions of pigs in gestation crates to save pennies on bacon cannot be morally justified.

Tom Regan and animal rights

Singer is a utilitarian: any practice can in principle be redeemed by the right balance of consequences. Tom Regan rejected this. In The Case for Animal Rights (1983), he argued that mammals at least one year old are "subjects-of-a-life": they have beliefs, desires, memory, an emotional life, and a welfare that can go better or worse for them as individuals. Beings of this kind possess inherent value — the same kind of value Kant claimed for rational humans — and may not be treated as mere means.

The practical difference matters. Singer can in principle accept some animal experimentation if the human benefit is enormous and the animal suffering small. Regan cannot: rights are not bargaining chips. He defended the abolition (not the reform) of commercial animal agriculture, sport hunting and trapping, and almost all animal experimentation.

Singer's utilitarianism vs Regan's rights view

	Singer (1975)	Regan (1983)
Underlying theory	Preference utilitarianism	Deontological rights
Criterion for moral status	Sentience (capacity to suffer)	Subject-of-a-life
Range of beings included	All sentient creatures	Mammals/birds ≥ 1 year (paradigm)
Trade-offs allowed?	Yes — interests can be aggregated	No — rights cannot be traded for utility
Verdict on factory farming	Wrong (suffering >> benefit)	Wrong (treats subjects as means)
Verdict on lifesaving experiments	Possibly permissible	Impermissible
Verdict on humane meat	Possibly permissible	Impermissible
Closest opponent	Bentham-style speciesists	Welfare-only reformers

Other key philosophers

• Christine Korsgaard, Fellow Creatures (2018). Argues from inside Kant's own framework that animals are ends in themselves: their good is a "final good," and Kant's principle of humanity properly extends to them.
• Martha Nussbaum, Frontiers of Justice (2006) and Justice for Animals (2022). Applies the capabilities approach: each sentient species has a characteristic set of capabilities — flourishing-relevant doings and beings — that justice requires the basic political structure to protect.
• Gary Francione, Introduction to Animal Rights (2000). Abolitionist: any "humane" use of animals is incoherent; the only consistent position is veganism. Animal-welfare reform entrenches use.
• Sue Donaldson and Will Kymlicka, Zoopolis (2011). Political-theory turn: domesticated animals are co-citizens, wild animals enjoy sovereignty, liminal animals (urban wildlife) are denizens. Rejects negative-rights-only frameworks.
• Rosalind Hursthouse, Ethics, Humans and Other Animals (2000). Virtue-ethical approach: a temperate, just, and compassionate person could not endorse modern industrial animal use.
• Carol Adams, The Sexual Politics of Meat (1990). Ecofeminist: the same conceptual structure that turns women into bodies turns animals into "absent referents" behind cuts of meat.

Worked example: factory-farmed pork

A modern industrial sow spends most of her life in a gestation crate roughly her own body size. She cannot turn around. Her piglets are taken from her at three weeks. The system exists because confinement reduces feed costs by perhaps 5–8%.

Singer's calculation. Sows are intelligent, social, and unambiguously sentient. The aggregate suffering across hundreds of millions of animals dwarfs the marginal human gain (cheaper bacon). The institution fails utilitarian justification.

Regan's verdict. Sows are subjects-of-a-life. Crating treats them as production units, not as ends. The institution violates inherent value and is wrong regardless of any aggregate benefit.

Korsgaard. The sow's good is a final good for her, not for us. Treating her as a mere means contradicts the formula of humanity even before any utilitarian arithmetic.

Nussbaum. The capability "to enjoy bodily integrity and characteristic activity" is denied. Justice forbids the basic structure of food production from organising around such denial.

Hursthouse. No one becomes a more virtuous person by participating; cheap pork is incompatible with the practical wisdom of a compassionate agent.

Five very different theories converge on the verdict. That convergence is one of the strongest arguments in applied ethics.

Counterarguments and replies

Objection: humans are special. We have language, culture, complex projects; animals do not. Reply (argument from marginal cases): human infants and severely cognitively impaired adults lack these capacities at the relevant level, yet rightly retain full moral status. So the special-property argument either downgrades them too — which we reject — or fails to exclude animals.

Objection: animals eat each other. Predation is natural. Reply: "natural" does not entail "morally permissible for humans" (consider violence against children). Wild predation involves agents we cannot reason with; industrial agriculture involves agents who can recognise an argument. The two cases are categorically different.

Objection: animals are necessary for nutrition. Reply: the American Dietetic Association and the British Dietetic Association have found well-planned vegan diets nutritionally adequate at all life stages. The empirical premise has been retired.

Objection: contractualism excludes animals. Contracts require parties who can negotiate. Reply (Rowlands, Korsgaard): contractualism's force comes from impartiality, and impartial reasoners would not accept being arbitrarily relegated to the production class. Even on its own logic, the theory has trouble excluding animals.

Objection: religious dominion. Scripture authorises human use. Reply: theological readings vary — Christian thinkers from Andrew Linzey to Pope Francis have argued the dominion concept implies stewardship, not unlimited use.

Variants and adjacent positions

• Welfarism. Reform animal industries; reduce suffering at the margin. Compatible with continued use.
• Abolitionism (Francione). All animal use is wrong; reform entrenches the system.
• Capabilities approach (Nussbaum). Justice protects species-typical flourishing.
• Political turn (Donaldson and Kymlicka). Animals as citizens, denizens, and sovereigns.
• Wild animal welfare (Pearce, Horta). Suffering in nature is a moral problem; intervention may be required.
• Religious animal ethics (Linzey). Christian theology of compassionate dominion.

Common confusions

• Animal ethics is not animal welfare. Welfare is one possible policy stance; ethics asks what stance is correct.
• Equal consideration is not equal treatment. Singer's principle says like interests count alike, not that mice and humans deserve the same things.
• Speciesism is structural, not personal. The charge is about how a practice or institution distributes weight, not about whether you happen to like dogs.
• Singer is not Regan. "Animal liberation" and "animal rights" are distinct theoretical programmes that often agree in conclusion and disagree in foundation.
• Sentience is the criterion most often used, but not the only one. Subject-of-a-life, capabilities, and being-a-Kantian-end are all on the table.