RR2
1
All Animals Are Equal (1974)*
PETER SINGER
*Adapted from the original version in Peter Singer’s 1974 “All Animals Are
Equal,” Philosophic Exchange: Vol. 5: No. 1, Article 6. Note that the current
version has been updated to replace antiquated language around mental
disability and references to “blacks and whites” used in the 1974 version.
* * *
In recent years a number of oppressed groups have campaigned vigorously for
equality. The classic instance is the Black Liberation movement, which
demands an end to the prejudice and discrimination that has made Black
people second-class citizens. The immediate appeal of the Black Liberation
movement and its initial, if limited, success made it a model for other
oppressed groups to follow. We became familiar with liberation movements for
Latinos, gay people, and a variety of other minorities. When a majority group—
women—began their campaign, some thought we had come to the end of the
road. Discrimination on the basis of sex, it has been said, is the last universally
accepted form of discrimination, practiced without secrecy or pretense even in
those liberal circles that have long prided themselves on their freedom from
prejudice against racial minorities. One should always be wary of talking of “the
last remaining form of discrimination.” If we have learnt anything from the
liberation movements, we should have learnt how difficult it is to be aware of
latent prejudice in our attitudes to particular groups until this prejudice is
forcefully pointed out.
A liberation movement demands an expansion of our moral horizons and an
extension or reinterpretation of the basic moral principle of equality. Practices
that were previously regarded as natural and inevitable come to be seen as the
result of an unjustifiable prejudice. Who can say with confidence that all his or
her attitudes and practices are beyond criticism? If we wish to avoid being
numbered amongst the oppressors, we must be prepared to re-think even our
most fundamental attitudes. We need to consider them from the point of view of
those most disadvantaged by our attitudes, and the practices that follow from
these attitudes. If we can make this unaccustomed mental switch we may
discover a pattern in our attitudes and practices that consistently operates so
as to benefit one group—usually the one to which we ourselves belong—at the
expense of another. In this way we may come to see that there is a case for a
new liberation movement. My aim is to advocate that we make this mental
switch in respect of our attitudes and practices towards a very large group of
beings: members of species other than our own—or, as we popularly though
misleadingly call them, animals. In other words, I am urging that we extend to
other species the basic principle of equality that most of us recognize should be
extended to all members of our own species.
2
All this may sound a little far-fetched, more like a parody of other liberation
movements than a serious objective. In fact, in the past the idea of “The Rights
of Animals” really has been used to parody the case for women’s rights. When
Mary Wollstonecraft, a forerunner of later feminists, published her Vindication
of the Rights of Women in 1792, her ideas were widely regarded as absurd,
and they were satirized in an anonymous publication entitled A Vindication of
the Rights of Brutes. The author of this satire (actually Thomas Taylor, a
distinguished Cambridge philosopher) tried to refute Wollstonecraft’s
reasonings by showing that they could be carried one stage further. If sound
when applied to women, why should the arguments not be applied to dogs,
cats, and horses? They seemed to hold equally well for these “brutes”; yet to
hold that brutes had rights was manifestly absurd; therefore the reasoning by
which this conclusion had been reached must be unsound, and if unsound
when applied to brutes, it must also be unsound when applied to women, since
the very same arguments had been used in each case.
One way in which we might reply to this argument is by saying that the case for
equality between men and women cannot validly be extended to nonhuman
animals. Women have a right to vote, for instance, because they are just as
capable of making rational decisions as men are; dogs, on the other hand, are
incapable of understanding the significance of voting, so they cannot have the
right to vote. There are many other obvious ways in which men and women
resemble each other closely, while humans and other animals differ greatly.
So, it might be said, men and women are similar beings and should have equal
rights, while humans and nonhumans are different and should not have equal
rights.
The thought behind this reply to Taylor’s analogy is correct up to a point, but it
does not go far enough. There are important differences between humans and
other animals, and these differences must give rise to some differences in the
rights that each have. Recognizing this obvious fact, however, is no barrier to
the case for extending the basic principle of equality to nonhuman animals. The
differences that exist between men and women are equally undeniable, and the
supporters of Women’s Liberation are aware that these differences may give
rise to different rights. Many feminists hold that women have the right to an
abortion on request. It does not follow that since these same people are
campaigning for equality between men and women they must support the right
of men to have abortions too. Since a man cannot have an abortion, it is
meaningless to talk of his right to have one. Since a pig can’t vote, it is
meaningless to talk of its right to vote. There is no reason why either Women’s
Liberation or Animal Liberation should get involved in such nonsense. The
extension of the basic principle of equality from one group to another does not
imply that we must treat both groups in exactly the same way, or grant exactly
the same rights to both groups. Whether we should do so will depend on the
nature of the members of the two groups. The basic principle of equality, I shall
3
argue, is equality of consideration; and equal consideration for different beings
may lead to different treatment and different rights.
So there is a different way of replying to Taylor’s attempt to parody
Wollstonecraft’s arguments, a way which does not deny the differences
between humans and nonhumans, but goes more deeply into the question of
equality and concludes by finding nothing absurd in the idea that the basic
principle of equality applies to so-called “brutes.” I believe that we reach this
conclusion if we examine the basis on which our opposition to discrimination on
grounds of race or sex ultimately rests. We will then see that we would be on
shaky ground if we were to demand equality for Black people, women, and
other groups of oppressed humans while denying equal consideration to
nonhumans.
When we say that all human beings, whatever their race, creed, or sex, are
equal, what is it that we are asserting? Those who wish to defend a
hierarchical, inegalitarian society have often pointed out that by whatever test
we choose, it simply is not true that all humans are equal. Like it or not, we
must face the fact that humans come in different shapes and sizes; they come
with differing moral capacities, differing intellectual abilities, differing amounts
of benevolent feeling and sensitivity to the needs of others, differing abilities to
communicate effectively, and differing capacities to experience pleasure and
pain. In short, if the demand for equality were based on the actual equality of all
human beings, we would have to stop demanding equality. It would be an
unjustifiable demand.
Still, one might cling to the view that the demand for equality among human
beings is based on the actual equality of the different races and sexes.
Although humans differ as individuals in various ways, there are no differences
between the races and sexes as such. From the mere fact that a person is
Black, or a woman, we cannot infer anything else about that person. This, it
may be said, is what is wrong with racism and sexism. The white racist claims
that white people are superior to Black people, but this is false—although there
are differences between individuals, some Black people are superior to some
white people in all of the capacities and abilities that could conceivably be
relevant. The opponent of sexism would say the same: a person’s sex is no
guide to his or her abilities, and this is why it is unjustifiable to discriminate on
the basis of sex.
This is a possible line of objection to racial and sexual discrimination. It is not,
however, the way that someone really concerned about equality would choose,
because taking this line could, in some circumstances, force one to accept a
most inegalitarian society. The fact that humans differ as individuals, rather
than as races or sexes, is a valid reply to someone who defends a hierarchical
society like, say, South Africa, in which all white people are deemed superior in
4
status to all Black people.1 The existence of individual variations that cut across
the lines of race or sex, however, provides us with no defense at all against a
more sophisticated opponent of equality, one who proposes that, say, the
interests of those with I.Q. ratings above 100 be preferred to the interests of
those with I.Q.s below 100. Would a hierarchical society of this sort really be so
much better than one based on race or sex? I think not. But if we tie the moral
principle of equality to the factual equality of the different races or sexes, taken
as a whole, our opposition to racism and sexism does not provide us with any
basis for objecting to this kind of inegalitarianism.
There is a second important reason why we ought not to base our opposition to
racism and sexism on any kind of factual equality, even the limited kind which
asserts that variations in capacities and abilities are spread evenly between the
different races and sexes: we can have no absolute guarantee that these
abilities and capacities really are distributed evenly, without regard to race or
sex, among human beings. So far as actual abilities are concerned, there do
seem to be certain measurable differences between both races and sexes.
These differences do not, of course, appear in each case, but only when
averages are taken. More important still, we do not yet know how much of
these differences is really due to [biological differences among] various races
and sexes, and how much is due to social/environmental differences that are
the result of past and continuing discrimination. Perhaps all of the important
differences will eventually prove to be social/environmental rather than genetic.
Anyone opposed to racism and sexism will certainly hope that this will be so,
for it will make the task of ending discrimination a lot easier; nevertheless it
would be dangerous to rest the case against racism and sexism on the belief
that all significant differences are environmental in origin. The opponent of, say,
racism who takes this line will be unable to avoid conceding that if differences
in ability did after all prove to have some genetic connection with race, racism
would in some way be defensible.
It would be folly for the opponent of racism to stake [their] whole case on a
dogmatic commitment to one particular outcome of a difficult scientific issue
which is still a long way from being settled. While attempts to prove that
differences in certain selected abilities between races and sexes are primarily
genetic in origin have certainly not been conclusive, the same must be said of
attempts to prove that these differences are largely the result of environment.
At this stage of the investigation we cannot be certain which view is correct,
however much we may hope it is the latter.
Fortunately, there is no need to pin the case for equality to one particular
outcome of this scientific investigation. The appropriate response to those who
claim to have found evidence of genetically-based differences in ability
between the races or sexes is not to stick to the belief that the genetic
1 Apartheid remained in effect in South Africa when this essay was published in 1974.
5
explanation must be wrong, whatever evidence to the contrary may turn up:
instead we should make it quite clear that the claim to equality does not
depend on intelligence, moral capacity, physical strength, or similar matters of
fact. Equality is a moral ideal, not a simple assertion of fact. There is no
logically compelling reason for assuming that a factual difference in ability
between two people justifies any difference in the amount of consideration we
give to satisfying their needs and interests. The principle of the equality of
human beings is not a description of an alleged actual equality among humans:
it is a prescription of how we should treat humans.
Jeremy Bentham incorporated the essential basis of moral equality into his
utilitarian system of ethics in the formula: “Each to count for one and none for
more than one.” In other words, the interests of every being affected by an
action are to be taken into account and given the same weight as the like
interests of any other being. A later utilitarian, Henry Sidgwick, put the point in
this way: “The good of any one individual is of no more importance, from the
point of view (if I may say so) of the Universe, than the good of any other”.2
More recently, the leading figures in contemporary moral philosophy have
shown a great deal of agreement in specifying as a fundamental presupposition
of their moral theories some similar requirement which operates so as to give
everyone’s interests equal consideration—although they cannot agree on how
this requirement is best formulated.3
It is an implication of this principle of equality that our concern for others ought
not to depend on what they are like, or what abilities they possess—although
precisely what this concern requires us to do may vary according to the
characteristics of those affected by what we do. It is on this basis that the case
against racism and the case against sexism must both ultimately rest; and it is
in accordance with this principle that speciesism is also to be condemned. If
possessing a higher degree of intelligence does not entitle one human to use
another for his own ends, how can it entitle humans to exploit nonhumans?
Many philosophers have proposed the principle of equal consideration of
interests, in some form or other, as a basic moral principle; but, as we shall see
in more detail shortly, not many of them have recognized that this principle
applies to members of other species as well as to our own. Bentham was one
of the few who did realize this. In a forward-looking passage, written at a time
when Black slaves in the British dominions were still being treated much as we
now treat nonhuman animals, Bentham wrote:
The day may come when the rest of the animal creation may acquire
those rights which never could have been witholden from them but by
2 The Methods of Ethics (7th Ed.), p. 382.
3 For example, R. M. Hare, Freedom and Reason (Oxford, 1963) and J. Rawls, A Theory of Justice (Harvard, 1972);
for a brief account of the essential agreement on this issue between these and other positions, see R. M. Hare,
“Rules of War and Moral Reasoning,” Philosophy and Public Affairs, vol. 1, no. 2 (1972).
6
the hand of tyranny. The French have already discovered that the
blackness of the skin is no reason why a human being should be
abandoned without redress to the caprice of a tormentor. It may one
day come to be recognized that the number of the legs, the villosity of
the skin, or the termination of the os sacrum, are reasons equally
insufficient for abandoning a sensitive being to the same fate. What
else is it that should trace the insuperable line? Is it the faculty of
reason, or perhaps the faculty of discourse? But a full-grown horse or
dog is beyond comparison a more rational, as well as a more
conversable animal, than an infant of a day, or a week, or even a
month, old. But suppose they were otherwise, what would it avail? The
question is not, Can they reason? nor, Can they talk? but, Can they
suffer?4
In this passage Bentham points to the capacity for suffering as the vital
characteristic that gives a being the right to equal consideration. The capacity
for suffering—or more strictly, for suffering and/or enjoyment or happiness—is
not just another characteristic like the capacity for language, or for higher
mathematics. Bentham is not saying that those who try to mark “the
insuperable line” that determines whether the interests of a being should be
considered happen to have selected the wrong characteristic. The capacity for
suffering and enjoying things is a prerequisite for having interests at all, a
condition that must be satisfied before we can speak of interests in any
meaningful way. It would be nonsense to say that it was not in the interests of a
stone to be kicked along the road by a schoolboy. A stone does not have
interests because it cannot suffer. Nothing that we can do to it could possibly
make any difference to its welfare. A mouse, on the other hand, does have an
interest in not being tormented, because it will suffer if it is.
If a being suffers, there can be no moral justification for refusing to take that
suffering into consideration. No matter what the nature of the being, the
principle of equality requires that its suffering be counted equally with the like
suffering—in so far as rough comparisons can be made—of any other being. If
a being is not capable of suffering, or of experiencing enjoyment or happiness,
there is nothing to be taken into account. This is why the limit of sentience
(using the term as a convenient, if not strictly accurate, shorthand for the
capacity to suffer or experience enjoyment or happiness) is the only defensible
boundary of concern for the interests of others. To mark this boundary by some
characteristic like intelligence or rationality would be to mark it in an arbitrary
way. Why not choose some other characteristic, like skin color?
The racist violates the principle of equality by giving greater weight to the
interests of members of his own race, when there is a clash between their
interests and the interests of those of another race. Similarly the speciesist
4 Introduction to the Principles of Morals and Legislation, ch. XVII
7
allows the interests of his own species to override the greater interests of
members of other species.5 The pattern is the same in each case. Most human
beings are speciesists. l shall now very briefly describe some of the practices
that show this.
For the great majority of human beings, especially in urban, industrialized
societies, the most direct form of contact with members of other species is at
mealtimes: we eat them. In doing so we treat them purely as means to our
ends. We regard their life and well-being as subordinate to our taste for a
particular kind of dish. l say “taste” deliberately—this is purely a matter of
pleasing our palate. There can be no defense of eating flesh in terms of
satisfying nutritional needs, since it has been established beyond doubt that we
could satisfy our need for protein and other essential nutrients far more
efficiently with a diet that replaced animal flesh by soy beans, or products
derived from soy beans, and other high-protein vegetable products.6
It is not merely the act of killing that indicates what we are ready to do to other
species in order to gratify our tastes. The suffering we inflict on the animals
while they are alive is perhaps an even clearer indication of our speciesism
than the fact that we are prepared to kill them.7 In order to have meat on the
table at a price that people can afford, our society tolerates methods of meat
production that confine sentient animals in cramped, unsuitable conditions for
the entire durations of their lives. Animals are treated like machines that
convert fodder into flesh, and any innovation that results in a higher
“conversion ratio” is liable to be adopted. As one authority on the subject has
said, “cruelty is acknowledged only when profitability ceases.”8 . . .
Since, as l have said, none of these practices cater for anything more than our
pleasures of taste, our practice of rearing and killing other animals in order to
eat them is a clear instance of the sacrifice of the most important interests of
other beings in order to satisfy trivial interests of our own. To avoid speciesism
we must stop this practice, and each of us has a moral obligation to cease
supporting the practice. Our custom is all the support that the meat industry
5 I owe the term speciesism to Richard Ryder.
6 In order to produce 1 lb. of protein in the form of beef or veal, we must feed 21 Ibs. of protein to the animal. Other
forms of livestock are slightly less inefficient, but the average ratio in the United States is still 1:8. It has been
estimated that the amount of protein lost to humans in this way is equivalent to 90 percent of the annual world protein
deficit. For a brief account, see Frances Moore Lappe, Diet for a Small Planet (Friends of The Earth/Ballantine, New
York 1971), pp. 4—11
7 Although one might think that killing a being is obviously the ultimate wrong one can do to it, l think that the infliction
of suffering is a clearer indication of speciesism because it might be argued that at least part of what is wrong with
killing a human is that most humans are conscious of their existence over time and have desires and purposes that
extend into the future see, for instance, M. Tooley, “Abortion and Infanticide,” Philosophy and Public Affairs, vol . 2,
no. I (1972). Of course, if one took this view one would have to hold—as Tooley does—that killing a human infant or
mental defective is not in itself wrong and is less serious than killing certain higher mammals that probably do have a
sense of their own existence over time
8 Ruth Harrison, Animal Machines (Stuart, London, 1964). For an account of farming conditions, see my Animal
Liberation (New York Review Company, 1975) from which “Down on the Factory Farm,” is reprinted in this volume
[Animal Rights and Human Obligations].
8
needs. The decision to cease giving it that support may be difficult, but it is no
more difficult than it would have been for a white Southerner to go against the
traditions of his society and free his slaves: if we do not change our dietary
habits, how can we censure those slaveholders who would not change their
own way of living?
The same form of discrimination may be observed in the widespread practice
of experimenting on other species in order to see if certain substances are safe
for human beings, or to test some psychological theory about the effect of
severe punishment on learning, or to try out various new compounds just in
case something turns up….
In the past, argument about vivisection has often missed the point, because it
has been put in absolutist terms: Would the abolitionist be prepared to let
thousands die if they could be saved by experimenting on a single animal? The
way to reply to this purely hypothetical question is to pose another: Would the
experimenter be prepared to perform his experiment on an orphaned human
infant, if that were the only way to save many lives? (I say “orphan” to avoid the
complication of parental feelings, although in doing so l am being overfair to the
experimenter, since the nonhuman subjects of experiments are not orphans.) If
the experimenter is not prepared to use an orphaned human infant, then his
readiness to use nonhumans is simple discrimination, since adult apes, cats,
mice, and other mammals are more aware of what is happening to them, more
self-directing and, so far as we can tell, at least as sensitive to pain, as any
human infant. There seems to be no relevant characteristic that human infants
possess that adult mammals do not have to the same or a higher degree.
(Someone might try to argue that what makes it wrong to experiment on a
human infant is that the infant will, in time and if left alone, develop into more
than the nonhuman, but one would then, to be consistent, have to oppose
abortion, since the fetus has the same potential as the infant—indeed, even
contraception and abstinence might be wrong on this ground, since the egg
and sperm, considered jointly, also have the same potential. In any case, this
argument still gives us no reason for selecting a nonhuman, rather than a
human with severe and irreversible brain damage, as the subject for our
experiments).
The experimenter, then, shows a bias in favor of his own species whenever he
carries out an experiment on a nonhuman for a purpose that he would not think
justified him in using a human being at an equal or lower level of sentience,
awareness, ability to be self-directing, etc. No one familiar with the kind of
results yielded by most experiments on animals can have the slightest doubt
that if this bias were eliminated the number of experiments performed would be
a minute fraction of the number performed today.
Experimenting on animals, and eating their flesh, are perhaps the two major
forms of speciesism in our society. By comparison, the third and last form of
9
speciesism is so minor as to be insignificant, but it is perhaps of some special
interest to those for whom this article was written. I am referring to speciesism
in contemporary philosophy.
Philosophy ought to question the basic assumptions of the age. Thinking
through, critically and carefully, what most people take for granted is, I believe,
the chief task of philosophy, and it is this task that makes philosophy a
worthwhile activity. Regrettably, philosophy does not always live up to its
historic role. Philosophers are human beings, and they are subject to all the
preconceptions of the society to which they belong. Sometimes they succeed in
breaking free of the prevailing ideology: more often they become its most
sophisticated defenders. So, in this case, philosophy as practiced in the
universities today does not challenge anyone’s preconceptions about our
relations with other species. By their writings, those philosophers who tackle
problems that touch upon the issue reveal that they make the same
unquestioned assumptions as most other humans, and what they say tends to
confirm the reader in his or her comfortable speciesist habits.
I could illustrate this claim by referring to the writings of philosophers in various
fields—for instance, the attempts that have been made by those interested in
rights to draw the boundary of the sphere of rights so that it runs parallel to the
biological boundaries of the species homo sapiens, including infants and even
mental defectives, but excluding those other beings of equal or greater capacity
who are so useful to us at mealtimes and in our laboratories. l think it would be
a more appropriate conclusion to this article, however, if I concentrated on the
problem with which we have been centrally concerned, the problem of equality.
It is significant that the problem of equality, in moral and political philosophy, is
invariably formulated in terms of human equality. The effect of this is that the
question of the equality of other animals does not confront the philosopher, or
student, as an issue itself—and this is already an indication of the failure of
philosophy to challenge accepted beliefs. Still, philosophers have found it
difficult to discuss the issue of human equality without raising, in a paragraph or
two, the question of the status of other animals. The reason for this, which
should be apparent from what I have said already, is that if humans are to be
regarded as equal to one another, we need some sense of “equal” that does
not require any actual, descriptive equality of capacities, talents or other
qualities. If equality is to be related to any actual characteristics of humans,
these characteristics must be some lowest common denominator, pitched so
low that no human lacks them—but then the philosopher comes up against the
catch that any such set of characteristics which covers all humans will not be
possessed only by humans. In other words, it turns out that in the only sense in
which we can truly say, as an assertion of fact, that all humans are equal, at
least some members of other species are also equal—equal, that is, to each
other and to humans. If, on the other hand, we regard the statement “All
humans are equal” in some non-factual way, perhaps as a prescription, then,
10
as I have already argued, it is even more difficult to exclude non-humans from
the sphere of equality.
This result is not what the egalitarian philosopher originally intended to assert.
Instead of accepting the radical outcome to which their own reasonings
naturally point, however, most philosophers try to reconcile their beliefs in
human equality and animal inequality by arguments that can only be described
as devious.
As a first example, I take William Frankena’s well-known article “The Concept
of Social Justice.” Frankena opposes the idea of basing justice on merit,
because he sees that this could lead to highly inegalitarian results. Instead he
proposes the principle that:
all men are to be treated as equals, not because they are equal, in any
respect, but simply because they are human. They are human because
they have emotions and desires, and are able to think, and hence are
capable of enjoying a good life in a sense in which other animals are
not.9
But what is this capacity to enjoy the good life which all humans have, but no
other animals? Other animals have emotions and desires and appear to be
capable of enjoying a good life. We may doubt that they can think—although
the behavior of some apes, dolphins, and even dogs suggests that some of
them can—but what is the relevance of thinking? Frankena goes on to admit
that by “the good life” he means “not so much the morally good life as the
happy or satisfactory life,” so thought would appear to be unnecessary for
enjoying the good life; in fact to emphasize the need for thought would make
difficulties for the egalitarian since only some people are capable of leading
intellectually satisfying lives, or morally good lives. This makes it difficult to see
what Frankena’s principle of equality has to do with simply being human.
Surely every sentient being is capable of leading a life that is happier or less
miserable than some alternative life, and hence has a claim to be taken into
account. In this respect the distinction between humans and nonhumans is not
a sharp division, but rather a continuum along which we move gradually, and
with overlaps between the species, from simple capacities for enjoyment and
satisfaction, or pain and suffering, to more complex ones.
Faced with a situation in which they see a need for some basis for the moral
gulf that is commonly thought to separate humans and animals, but can find no
concrete difference that will do the job without undermining the equality of
humans, philosophers tend to waffle. They resort to highs sounding phrases
like “the intrinsic dignity of the human individual”;10 they talk of the “intrinsic
9 In R. Brandt (ed.), Social Justice (Prentice Hall, Englewood Cliffs, 1962), p. 19
10 Frankena, op. cit. p. 23
11
worth of all men” as if men (humans?) had some worth that other beings did.
not,11 or they say that humans, and only humans, are “ends in themselves,”
while “everything other than a person can only have value for a person.”12
This idea of a distin