The weight of animal interests

The weight of animal interests

All beings who can have positive and negative experiences have an interest in being positively affected and in not being negatively affected. In other words, they have an interest in having their wellbeing maximized and their suffering minimized. Sentient animals, therefore, have an interest in not suffering and in being able to enjoy their lives. Being able to enjoy their lives entails, among other things, that they have an interest in not being killed, so they have the opportunity to have positive experiences.

However, most people assume that if we should consider the interests of others then we should focus on helping other humans rather than nonhuman animals. The usual reason given is that the interests of humans are more important than those of other animals. In particular, this idea is defended because of the many different harms that are suffered in the world by human beings.

A common answer to this is that caring for humans should not exclude caring for other animals as well. However, this is only a partial answer, since it doesn’t address the claim that the interests of nonhuman animals are not very important. Of course, many people reject caring for nonhuman animals because they have a speciesist viewpoint, but as the arguments against speciesism shows, such arguments don’t work. However, people can defend a disregard for nonhuman animals, even if they don’t accept speciesism, if they think that nonhuman interests have less weight than those of humans.

Why the interests of nonhuman animals are very important

There are two main things we have to consider when assessing the weight of animal interests.

First of all, we must consider whether they are beings who can have positive and negative experiences. Animal sentience explains the arguments used to evaluate this question. The arguments show that we have sound reasons to conclude that all animals with a centralized nervous system are potentially sentient, and that for many of them the evidence for it is overwhelming, for behavioral, evolutionary and in particular physiological reasons (as explained in indicators of animal suffering). In addition we must bear in mind that, as explained in animal interests, human interests aren’t more important than those of nonhuman animals because we can suffer in certain psychological ways. Physical suffering and enjoyment aren’t less significant than psychological suffering and enjoyment, and, moreover, many nonhuman animals are capable of psychological suffering and enjoyment as well.

Second, once we have acknowledged that nonhuman animals can be harmed and benefited in significant ways, just as humans can, we need to know what their actual situation is. Upon examination we see that the harms they suffer really are enormous. This is true in two different ways:

  • We must look at the intensity of the harms nonhuman animals suffer. They are usually killed in the process of the exploitation they suffer, as when they are slaughtered for the production of food. Moreover, they are often also caused to suffer terribly during their lives, as happens on farms, in laboratories and in many other places in which they are used. On farms, they are in most cases confined for all their lives in dark places in which they can barely move, in which they suffer from all kinds of diseases and injuries until they are taken to a slaughterhouse. In laboratories, they are also confined and forced to undergo all kinds of painful procedures which also lead them to suffer extreme distress. In contrast to humans, nonhuman animals generally don’t get to enjoy any of the benefits that humans often receive from others, in particular when they need help and support. This applies particularly in the case of those animals who live in nature. The vast majority of nonhuman animals are left vulnerable to suffer and die regardless of whether they could benefit from our help. As the section on the situation of animals in nature shows, the harms suffered by animals in the wild are also very intense. Often they starve, suffer terrible injuries and diseases, or are killed by parasites or other animals, etc. These harms often pass completely unnoticed by us, but they are terrible for them.
  • In terms of numbers, the weight of the interests of nonhuman animals is also dramatic. Around 60 billion mammals and birds are killed in slaughterhouses every year.1 It has been estimated that between 1 and 3 trillion fishes are captured in the sea,2 and hundreds of billions are raised to be killed in fish factories every year.3 There are around seven billion human beings, whose life expectancy is, on average, around 60 years. If we consider all the animals who live in the world, including those who live in nature, and who have interests of their own, the number of animals is just immense. It has been estimated that there may be more than 1019 animals, that is, a 1 with 19 zeros after it, which is ten billion nonhuman animals for each human being.4 Among them, the most numerous are invertebrates, in particular copepods and insects. Because of population dynamics, most of them die in misery shortly after they come into existence.5 These astronomical figures show that quantitatively the harms nonhuman animals suffer are also extremely significant.

For these reasons, we have to conclude that the weight of the interests of all these animals is massive. We can only dismiss the interests of nonhuman animals if we assume a blatantly speciesist view that only humans matter.

What should we do about it?

What we have seen above provides sufficient reasons to not cause nonhuman animals to suffer and to not impede their enjoyment. Nonhuman animals have very important interests in not being harmed. In addition, the same reasons entail that animals have an interest in having their suffering prevented and their positive wellbeing promoted. So if we care about nonhuman animals, we can refrain from causing them to suffer and also promote their enjoyment. We can also try to prevent negative things from occurring to them. The table below summarizes how our actions towards nonhuman sentient beings can be classified:6

Negative for animals

Positive for animals

Causing something

To cause them to suffer

To cause them to enjoy


To obstruct or end their enjoyment

To obstruct or end their suffering

Stopping an obstruction

To stop something from occurring that obstructs or alleviates their suffering

To save them from something that obstructs or eliminates their enjoyment

Letting be

To let their suffering occur

To let their enjoyment occur

Letting an obstruction be

To let an obstruction to their enjoyment occur

To let an obstruction to their suffering occur

This table shows that we can do more than just refrain from causing suffering to nonhuman animals; we can also act in other ways towards them, and in particular to help them when we are able to reduce their suffering and promote their happiness. And as we have seen here, we have very good reasons to do so.

Further readings

Dawkins, M. S. (1980) Animal suffering, New York: Chapman and Hall.

Dawkins, M. S. (1990) “From an animal’s point of view: Motivation, fitness, and animal welfare”, Behavioral and Brain Sciences, 13, pp. 1-61.

Dawkins, R. (1995) River out of Eden: A Darwinian view of life, ch. 5, New York: Basic Books.

DeGrazia, D. (1996) Taking animals seriously: Mental life & moral status, Cambridge: Cambridge University Press.

Frey, R. G. (1980) Interests and rights: The case against animals, Oxford: Oxford University Press.

Leahy, M. P. T. (1991) Against liberation: Putting animals in perspective, London: Routledge.

Matheny, G. & Chan, K. M. A. (2005) “Human diets and animal welfare: The illogic of the larder”, Journal of Agricultural and Environmental Ethics, 18, pp. 579-594.

Matheny, G. & Leahy, C. (2007) “Farm-animal welfare, legislation and trade”, Law and Contemporary Problems, 70, pp. 325-358 [accessed on 21 September 2012].

Norwood, F. B. & Lusk, J. J. (2011) Compassion, by the pound: The economics of farm animal welfare, Oxford: Oxford University Press.

Pluhar, E. (1995) Beyond prejudice: The moral significance of human and nonhuman animals, Durham: Duke University Press.

Rollin, B. E. (1989) The unheeded cry: Animal consciousness, animal pain and science, Oxford: Oxford University Press.

Salem, D. J. & Rowan, A. N. (eds.) (2001) The state of the animals 2001, Washington: Humane Society of the United States.

Sapontzis, S. F. (1990) “The meaning of speciesism and the forms of animal suffering”, Behavioral and Brain Sciences, 13, pp. 35-36.

Singer, P. (1990) “The significance of animal suffering”, Behavioral and Brain Sciences, 13, pp. 9-12.

Tomasik, B. (2007) “How much direct suffering is caused by various animal foods?”, Essays on Reducing Suffering [accessed on 17 June 2016].

Tomasik, B. (2009a) “Comments on Compassion by the pound”, Essays on Reducing Suffering [accessed on 10 January 2014].

Tomasik, B. (2009b) “Do bugs feel pain?”, Essays on Reducing Suffering [accessed on 15 December 2016].

Tomasik, B. (2012) “Suffering in animals vs. humans”, Essays on Reducing Suffering [accessed on 3 May 2015].

Tomasik, B. (2015) “The importance of wild animal suffering”, Relations: Beyond Anthropocentrism, 3, pp. 133-152 [accessed on 20 November 2015].


1 Food and Agriculture Organization of the United Nations (2023) “Crops and livestock products”, FAOSTAT [accessed on 16 September 2023].

2 Mood, A & Brooke, P. (2024) “Estimating global numbers of fishes caught from the wild annually from 2000 to 2019”, Animal Welfare, 33, e6 [accessed on 11 May 2024].

3 Food and Agriculture Organization of the United Nations (2010) “Global aquaculture production 1950-2011”, Fisheries and Aquaculture Department, Global Statistical Collections.

4 Tomasik, B. (2009c) “How many wild animals are there?”, Essays on Reducing Suffering [accessed on 15 December 2016]. Sabrosky, C. W. (1952) “How many insects are there?”, in United States Department of Agriculture. Insects: The yearbook of agriculture, Washington, D. C.: United States Department of Agriculture.

5 Ng, Y.-K. (1995) “Towards welfare biology: Evolutionary economics of animal consciousness and suffering”, Biology and Philosophy, 10, pp. 255-285. Horta, O. (2010) “Debunking the idyllic view of natural processes: Population dynamics and suffering in the wild”, Télos, 17, pp. 73-88 [accessed on 5 January 2013].

6 On a related classification of our different duties towards others and on why they come altogether see Kagan, S. (1989) The limits of morality, Oxford: Clarendon University Press.