The Declaration on Great Apes states that chimpanzees, gorillas and orang-utans, as well as human beings, should be granted the rights to life, liberty and the absence of deliberately inflicted pain. The argument on which this statement is founded consists of the following premises and conclusions:
P1 Beings who are equal in the moral sense ought to be treated equally.
P2 Beings are equal in the moral sense if their mental capacities and emotional lives are roughly at the same level.
P3 The mental capacities and emotional lives of human beings and other great apes are roughly at the same level.
C1 Therefore, human beings and other great apes ought to be treated equally.
P4 Human beings ought not to be killed, imprisoned or tortured unless certain specific conditions prevail.
C2 Therefore, other great apes ought not to be killed, imprisoned or tortured unless the same specific conditions prevail.
We believe that this argument is essentially sound, at least in the sense that those human beings who imprison, torture and kill chimpanzees, gorillas and orang-utans for scientific (or allegedly scientific) or commercial purposes are acting wrongly and should be stopped. (We say ‘at least’ since one might feel uneasy about bringing human law and order to the orang-utans, gorillas and chimpanzees themselves, i.e. to intervene coercively if orang-utans, gorillas and chimpanzees within their own natural communities act violently towards each other. Cultural toleration can perhaps be argued for by referring to the probable harm that human interventions would inflict on individuals within these communities.)
But what about those scientists, philosophers and lay persons who disagree with us? Obviously, they must claim that one of the premises of the argument is false, or that the logical inference from the premises to the conclusion is somehow invalid. Let us see how such claims could be defended.
Equal Treatment for Equals
In the first premise of the argument (P1) the words ‘equal’ and ‘equally’ should not be taken to mean ‘similar’ and ‘similarly’, as those opposing equality between races, species and the sexes frequently suggest. Beings who are equal in the moral sense need not be exactly like one another. The obvious individuality of male adult human beings, for instance, has never deterred those who have declared that all men should be treated equally. The idea is, rather, that there are certain relevantly similar features in all beings who belong to the same category of moral equals which make them members of the category.
The same point applies, with necessary changes, to the equal treatment of beings who are relevantly similar. Consider certain advanced medical procedures performed on humans. At any given moment, for example, there are a number of people all around the world who ought to be given blood transfusions. But even though all people are presumably equal in the moral sense, it does not follow that blood transfusions ought to be given to everybody. There are those who do not need additional blood at the present, and there are those who do not wish alien blood to circulate in their veins. Equal treatment in this case does not mean that perfectly healthy individuals should be seized in the street and provided with blood transfusions. Nor does it mean that blood or blood products should be forcibly injected into the veins of competent adults who, due to their religious beliefs, oppose the idea. Equal treatment implies that every being in a category of moral equals ought to be treated according to its or her or his needs and desires. Some theorists have called this type of equality ‘equality of consideration’, stating that the interests of all members of the community of equals should be taken equally into account.
Given these qualifications, P1 can hardly be attacked from any quarter. Almost all substantial theories of justice and equality can be founded on the general principle that relevantly similar beings ought to be treated in a relevantly similar manner. The principle in this form is a tautology rather than an action-guiding moral statement, and additional premises are therefore needed to give the argument its normative content.
The Community of Equals
The second premise of the argument (P2) states the criteria which divides beings into different moral categories. According to the premise, communities of moral equals consist of beings who are approximately at the same level as regards their mental capacities and emotional lives. For instance, assuming that trees have no thoughts or feelings or social contacts with each other, they belong to the same moral category as stones and raindrops. (The assumption can be false in some sense, but this does not influence the following argument, which is hypothetical.) This similarity means that if one can justifiably kick a stone or capture a raindrop, one can also legitimately kick trees and build fences around them. Irrelevant differences, like the fact that trees are living organisms while stones and raindrops are inanimate objects, do not count in the matter.
There are a number of competing views which state that psychological and social abilities are not the proper basis for assessing how different beings ought to be treated. The alternative criteria which have been suggested range from species membership, through merit and the ability to claim one’s due, to general utility. We shall argue below that all these alternative solutions are either unsound or yield the same normative conclusions as the original premise on which the Declaration is founded.
But whatever the status of the Declaration’s approach to equality, the third premise of the argument (P3) can also be independently challenged. Many scientists and philosophers have repeatedly argued that the mental capacities and emotional lives of chimpanzees, gorillas and orang-utans are not sufficiently developed to justify the comparison with human cognition and feelings. The falsification or verification of such claims is, of course, mainly a matter for empirical scientists. There are, however, two conceptual points which seem to support the view expressed in the Declaration. First, most scientists who maintain that human beings and other great apes are too unlike each other to be counted as moral equals also hold the view that experimentation on chimpanzees, due to the striking similarities between the species, is the only way to ensure that new medical procedures are safe for humans. Second, although it may be true that adult chimpanzees, gorillas and orang-utans are, as a rule, less intelligent and sensitive than average adult human beings, it should be remembered that the same remark also applies to many humans, including very young children and people with a mental handicap. Assuming that the general principle stated in premise P2 is valid, it is difficult to refute the argument by attacking its third premise (P3).
Basic Moral Principles
The fourth premise of the argument states the qualified moral principle that human beings ought not to be killed, imprisoned or tortured unless certain specific conditions prevail. By these ‘specific conditions’ different theorists have meant slightly different things. In the Declaration it is stated that killing human beings may be justifiable in self-defence, and that their imprisonment can be legitimate only if it is the result of adequate legal processes. According to the Declaration, an adequate legal process should not lead to the imprisonment of human beings (or other great apes) unless they have been convicted of a crime, or their continued detention is in their own best interest, or they constitute a threat to the safety of others. The deliberate infliction of severe pain is rejected in the Declaration without exceptions.
All these qualifications can in fact be contested. As for the clause on taking lives, there are those who believe that killing is always wrong and should not be sanctioned even in self-defence. There are also those who assert that actions which are condemned as criminal in modern societies do not justify imprisonment. Crime, they hold, is created and maintained by society itself, and the rules of crime prevention are defined so as to benefit the rich and the powerful and to oppress the poor and the powerless. Besides, they argue, confinement neither cures criminality nor protects the safety of ordinary citizens, since prisons promote violent and antisocial behaviour instead of eradicating it.
In addition to these pacifist and abolitionist objections, the qualifications stated in the Declaration can also be challenged from a more self-centred point of view. Not everybody believes that the individual’s own best interest can be served by restricting his or her liberty. And some of us may find it theoretically unsound to condemn the infliction of pain under all circumstances while condoning, at the same time, killing in self-defence.
But although there may be differences of opinion when it comes to applying the moral principles stated in the Declaration, this does not in any way undermine the validity of those principles themselves. Details aside, most people surely believe that human beings ought not to be killed, imprisoned or tortured unless there are some exceptionally weighty reasons for doing so. Consequently, assuming that human beings and other great apes are to be treated equally, as the first conclusion of the argument (Cl) affirms, chimpanzees, gorillas and orang-utans should be similarly protected against death, constraint and deliberately inflicted pain. The preferential treatment of one species at the expense of the other three can only be justified by showing that Cl is invalid. And since the first premise of the argument was found to be noncontroversial and the third premise beyond conceptual proof, the only way in which philosophers can argue that human beings ought to be treated differently from other great apes is to attack the second premise (P2).
Against the Mental Criteria of Moral Equality
There are two ways in which the psychological and social criteria for moral equality are usually interpreted, and both interpretations introduce their own difficulties. First, it is possible to define the sufficient ‘mental capacities and emotional life’ referred to in the Declaration strictly, so as to ensure that beings who fulfil the criteria cannot fail to deserve equal consideration and treatment. Seen from the viewpoint of adult human beings, it would be natural to include, for instance, vivid self-awareness and mutual verbal communication among the necessary requirements. The problem with this solution is, however, that it would exclude human infants and intellectually disabled human beings as well as most other animals from the community of moral equals. Many people seem to feel that this would be an unacceptable conclusion, especially as regards the human beings who do not meet the standards. Second, it is possible to define the criteria broadly, and state that even rudimentary self-awareness, combined with the ability to suffer pain and distress, is sufficient for membership in the community of equals. This, manifestly, is the view taken in the Declaration. Those who criticise the mental approach can argue, however, that the solution would extend the community of equals beyond all reasonable limits. If the ability to suffer is used as the decisive criterion for equal treatment, then most ‘higher’ animals — dolphins, pigs and the rest — would have to be granted the rights to life, liberty and the absence of deliberately inflicted pain. And such a result would, according to the opponents of the mental approach, be patently absurd.
This challenge can be met in two ways without rejecting the mentalistic view. On the one hand, the extension of the community of equals beyond great apes does not necessarily deter those who find the Declaration defensible in the first place. Although further expansions in the category of equals would lead to drastic changes in the views and lifestyles of humans, this does not prove that the expansions would be absurd. The abolition of slavery presumably altered the way of life in the Southern states of the USA, but few people today would regard this as an argument for slave-holding. The Declaration does not rule out the possibility that other animals besides great apes may have to be granted equal rights.
On the other hand, it is also possible to meet the challenge by analysing in more detail the relationship between the rights and mental abilities of different beings. There are animals, including great apes like ourselves, who, in addition to their ability to suffer from constraint and physical pain, are aware of themselves as distinct entities whose existence is temporally continuous. Only these individuals can suffer from their own demise, or the thought of their own nonbeing in the future, and only they possess the right to life in the strict sense. There are also animals who lack self-awareness but who are sentient and capable of being distressed if they are imprisoned – they have the rights to liberty and the avoidance of torture. Finally, beings who are merely sentient, i.e. only sensitive to physical suffering, are entitled to protection against deliberately inflicted pain.
The definition of these three subcategories of moral equals is, ultimately, an empirical issue. Even without further empirical scrutiny, however, the division shows that whatever difficulties there may be within the mentalistic view, these do not constitute compelling reasons for rejecting it. This is not to say that the approach is universally accepted. But unless an alternative theory can be found which clearly supersedes the psychological criteria, the foundation of the Declaration cannot be effectively criticised.
Membership in a Species
One of the most popular alternatives to the mentalistic approach is the employment of biological criteria. At the core of the view is the claim that the community of moral equals can be extended only to human beings, i.e. to the members of the species Homo sapiens. When the theory is presented in its orthodox form, no reference is made to the abilities, achievements or opinions of individual human beings. What is considered focal is that humankind as a whole is entitled to preferential treatment among the species.
The view that a species is morally important can be defended by two methods, neither of which leads to tenable results. First, some proponents of the view argue that it is God’s will that human beings use animals to satisfy their needs. Second, others argue that the creation of law and society sets human beings apart from other animals. It would be absurd to burden chimpanzees, gorillas and orang-utans with legal or social duties, and it would therefore also be absurd to provide them with the corresponding rights.
Unfortunately for theistic speciesism, the Bible does not in fact give any unequivocal grounds for killing, imprisoning or torturing non-human animals. What Genesis claims is that human beings ought to be the rulers of Creation, not that they should use other animals as a means to their own ends. It is not, after all, part of the ruler’s duties to eat his or her subjects nor imprison them without adequate grounds. Even assuming that Judeo-Christian beliefs are relevant to critical morality, the Declaration cannot be attacked by appeals to God’s will.
The humanistic view, in its turn, is based on facts but it falls short of applying these facts consistently. Chimpanzees, gorillas and orangutans have not participated in the making of prevailing laws and social policies, but the same observation applies to the majority of humans. The ‘mankind’ which is responsible for most modern regulations and political procedures consists mostly of white male adult humans, not of all human beings without distinction of age, race, sex or social position. Subsequently, the humanist should not draw the boundary of moral equality between human and nonhuman beings, but between white male adult humans and other human and nonhuman animals.
Other criteria for determining how different beings ought to be treated include merit, the ability to claim one’s due and general utility. None of these approaches fares, however, any better than pure speciesism.
Those moralists who believe that theories of justice and equality should centre on the concept of merit state that all beings, regardless of their natural features or social background, should be treated according to their merits, or should be ‘given their just deserts’. Hardworking people and productive domestic animals deserve the full respect and consideration of others, whereas beings who do not earn their dues deserve considerably less. When this view is applied to laboratory animals, including chimpanzees, gorillas and orang-utans, the moral is two-fold. On the one hand, the beasts who ‘serve well’ as experimental subjects also deserve to be treated well by their examiners. On the other hand, however, laboratory animals are by definition exposed to many hazards and indignities. Chimpanzees, gorillas and orang-utans who are supposed to further scientific progress often live their entire lives in captivity, and they are frequently subjected to physical pain. Moreover, even if senseless cruelty towards these human-like apes may be rare, their lives are in many cases shortened and abruptly terminated as a result of the experiments.
Even those who do not find it disquieting to think about imprisoned chimpanzees, gorillas and orang-utans have to admit, however, that the theory of merits and deserts is, in the last analysis, untenable in the present context. There are many human beings who, like other great apes, are unable to earn their dues by productive work as understood by the able-bodied and able-minded section of the human community. Yet most people would, and rightly, hesitate to cast these unfortunate individuals in the role of experimental animals. When it comes to members of our own biological species, we tend to complement the ethics of deserts with the ethics of compassion or rights. But the theory of just deserts gives no adequate grounds for limiting the application of these moral safeguards to humans. The theory assumes rather than argues that chimpanzees, gorillas and orang-utans should be treated differently from the other great ape.
The Ability to Claim One’s Due
One argument which is frequently employed to defend speciesism is based on the fact that chimpanzees, gorillas and orang-utans do not have the ability to claim their dues, whatever the criteria for measuring those dues may be. The proponents of the argument seem to presume that beings can only have rights if they have themselves formulated these rights, and if they have successfully fought to achieve them. This is the way, the proponents say, in which factory workers, women, and racial minorities have managed to secure their political rights in many countries, and this is the way in which rights ought to be achieved.
There are several critiques to be voiced against the view. First, the rights of factory workers, women and various racial groups have not been recognised in all parts of the world. Should we infer from this that members of these groups are not entitled to life, liberty and the absence of deliberately inflicted pain if they happen to live in countries which do not acknowledge these rights? Second, in many affluent countries children and people with a mental handicap are protected by legal rights which they have not achieved for themselves. Should all these rights be abrogated? Third, the ability to claim one’s due may have some relevance in the context of legal and political rights. But as the foregoing examples show, the criterion cannot be employed in ethical arguments.
Protection and compassion cannot with good conscience be restricted to those who know how to earn them.
The final argument for speciesism is an appeal to the general utility of imprisoning and studying chimpanzees, gorillas, orang-utans and other nonhuman animals for scientific purposes. Animal experimentation is the cornerstone of modern biomedicine, and the foundation of many technological advances in health care. Its discontinuation would indirectly lead to immeasurable human suffering, as the progress of medical science would come to a halt. Consequently, our present way of life would be substantially altered.
This crude utilitarian view can be challenged both factually and theoretically. One empirical point which can be queried is the actual need for animal experimentation in modern medicine and health care. Many alternative methods of examining living organisms have been developed during the last decades, and there are scientists who claim that tests involving living animals can be entirely replaced by employing these new methods. It is possible, of course, that experiments on chimpanzees, gorillas and orang-utans are irreplaceable. But it is equally possible that they are only regarded as irreplaceable by scientists who do not have adequate information concerning the alternative test methods. If this is the case, then little or no human suffering would follow from the abandonment of experiments on nonhuman great apes. The theoretical difficulty with the crude utilitarian view is its implicit reliance on the sanctity of status quo in social life. It is, no doubt, true that the lives of many humans would be altered by the recognition and enforcement of the Declaration on Great Apes. But this in itself does not amount to an argument against the Declaration. The lives of many slave-holders were unquestionably changed by the abolition of slavery, but this does not undermine the essential validity of the new rule. Unjust and immoral social arrangements ought to be criticised even if it means inconvenience for those who have previously profited at the expense of others.
The Validity of the Declaration
It seems, then, that no outstanding and indisputably valid alternatives can be found for the mental criteria of moral equality. The second premise of our argument (P2) is, therefore, valid in the sense that it cannot be superseded by other popular views on the boundaries of
equality. This, in its turn, implies that the argument as a whole is conceptually sound: assuming that the psychological facts stated in the third premise (P3) are true, both the premises and the inferences of the argument are sound. Given that chimpanzees, gorillas and orang-utans have mental capacities and emotional lives which roughly equal our own, we should not hesitate to grant equal rights to life, liberty and the absence of torture to all great apes regardless of race, gender or species.
Acknowledgement – Our thanks are due to Mark Shackleton, Lecturer in English, University of Helsinki, for revising the language of the paper.
 See, for example, P. Singer, ‘All animals are equal’, in P. Singer (ed.), Applied Ethics (Oxford University Press, Oxford, 1986), pp. 215-28.
 Cf. Singer, ‘All animals are equal’, pp. 217 ff.
 Those who believe that all life is sacred (people like Albert Schweitzer) could argue that if trees are kicked hard enough, they suffer. These theorists may claim that we can witness the suffering of trees by observing the emergency operations by which they try to repair the damage caused by external forces. Presumably, what the proponents of the view have in mind is that we feel sympathy towards the attempts of living beings while the movements of inanimate objects leave us untouched. But this is not, strictly speaking, true. In fact, inanimate objects can also ‘behave’ in ways which can be interpreted anthropomorphically. When stones are thrown up from the ground, they immediately try to return to their ‘natural place’. When raindrops are captured, they try to find other ways to reach the ground. And in computer games the player can often cause ‘damage’ which the computer tries to prevent, minimise and repair. Theoretically, nothing prevents people from feeling sympathy towards these efforts.
 The creation of animals (two different stories) is described in Genesis 1: 26—8 and Genesis 2: IS—22.
Texto de autoria dos filósofos Heta Häyry e Matti Häyry para o The Great Ape Project New York: St. Martin’s Griffin, pg. 173-182, publicado originalmente em 1993.