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The ethics of animal experimentation

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At the heart of the debate about the ethics of animal experimentation lies the question of the moral relationship between humans and non-humans. Western philosophers over the centuries have regarded humans in a different light to the rest of the animal kingdom. For example, Aristotle believed that there was a hierarchy of animals, with humans at the top, as humans could reason and had “rational souls”. Even within humans there was a hierarchy: men were more rational than women, and Hellenes were more rational than other races. This made it perfectly acceptable to enslave “barbarians”. Descartes considered that non-humans were insentient “machines”. As such, they could feel no pain, and so could be exploited ruthlessly. Kant, on the other hand, accepted that animals could suffer, but, by lacking moral autonomy, they also lacked moral status.

These were not the only views. Jeremy Bentham, writing at the end of the 18th century, suggested that, “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 the hand of tyranny. … The question is not, Can they reason? Nor Can they talk? But, Can they suffer?” (quoted in Singer1).


One of the moral features of the second half of the 20th century has been the emergence of the concept of Human Rights. These have included equality between the sexes, between ethnic groups, between religious groups. If previously held beliefs in the superiority of, for example, men over women, whites over non-whites, are no longer tenable, then is the idea that humans are superior to non-humans still tenable? A number of moral philosophers have argued that it is not.

Peter Singer’s 1975 book, Animal liberation, brought the debate to a much wider audience than previous texts.1 In it he catalogued the suffering inflicted on animals in the name of science and farming and argued that such animals deserved equal consideration, based on their capacity to suffer. He adopted the utilitarian principle that moral judgements should be made based on equal interests (for example, an interest in not suffering) irrespective of sex, ethnicity, or now, species. To make a distinction between humans and non-humans is “speciesism”, an argument no better than sexism or racism.


Utilitarianism uses the aggregation of harms and benefits to determine the right course of action. This may appear quite appealing as it reduces moral choice to simple arithmetic. However, how does one quantify harms and benefits, especially in dealing with animal research? The development of cardiopulmonary bypass involved countless animal experiments (an enormous harm), but has, eventually, resulted in the success of open heart surgery (an enormous benefit).2 The utilitarian argument or calculation might very well conclude that this was a justifiable use of those animals.

Singer1 does not take an absolutist approach to animals and their rights, accepting that overwhelming “good”, such as a cure for an incurable condition, could justify an experiment. He also acknowledges that there are differences between sentient species. Humans, who on the whole, have complex language skills, self-awareness, an awareness of others and the capacity to plan for the future, are at the extreme end of the spectrum of species. As such they may have “preference” over other species. Similarly non-human primates may have preference over rodents.

Tom Regan, on the other hand, has argued that animals have rights in themselves.3 An animal’s life has inherent value to that animal and confers moral status to that individual. Humans have no right to exploit other animals irrespective of possible benefits to humans. Regan has stated, “The best we can do in terms of not using animals is not to use them”.3

Other philosophers have argued in favour of animals using concepts such as “contractarianism” and “reverence for life”. These concepts have not received as much attention as those of Singer and Regan.


There are counter arguments, which hinge on whether animals are moral beings. Fox concludes that only autonomous beings have rights and that, “lacking in various degrees the possession of capacities on which moral autonomy or agency depends, animals fail to meet the conditions specified for full membership in the moral community and likewise fail to qualify for having rights.”4 In a similar vein Scruton writes that, “We must distinguish moral from non-moral beings. The first exist within a web of reciprocal rights and obligations created by their dialogue. The second exist outside that web and it is both senseless and cruel to try to bind them into it.”5 Although animals have no rights we may have duties to them. Scruton also makes a distinction between wild animals and those we have made dependent on us. Carruthers has come to a similar conclusion: “…some version of contractualism provides us with the most acceptable framework for moral theory, and from such a perspective animals will be denied moral standing.”6

Frey believes that animals have moral standing; animal life has some value. But not all animal life has the same value, and human life is more valuable than animal life.7 He has also argued that a healthy animal may have a higher value than an unhealthy or “defective” human, in which case the human should be used rather than the animal.

Part of the problem, when invoking moral philosophy to solve the ethical problem of animal experimentation, is the tendency to try to resolve it using a single philosophical construct, be it utilitarianism, a rights-based approach, or contractualism, or any other. Instead, an approach similar to that used to resolve ethical dilemmas in clinical practice may be more helpful. This will include elements of all these principles.

Was it right, was it ethical, to slaughter “36 healthy hybrid canines” in the name of medicine, as was done in a study published in this issue of the journal?8 To show that emergent cardiopulmonary bypass may delay death after a penetrating cardiac wound? And that surgery is necessary to achieve any chance of survival?

There may be no universally accepted answer. Instead, the answer will depend on personal beliefs: whether one believes that animals have moral status, and/or rights; whether we have obligations to animals in our care; whether we take a utilitarian, or a preference utilitarian, approach to the question.

Singer, and Frey, might ask whether the study is so important that it could, or should, have been done on neonates or demented humans, who either have not gained or have lost their autonomy? If the answer to that is no, then they might argue that it is also unethical to do it on healthy animals…. Or is that just absurd?


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  • Competing interest: None declared

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