What is Speciesism According to Peter Singer?

Peter Singer identifies speciesism as the view that a being’s moral status depends upon its species, the kind of being it is.

Jan 4, 2024By Ryan Alexander, PhD Philosophy

speciesism according to peter singer


In Animal Liberation (1975), Peter Singer tells us: “Most human beings are speciesists.” This is his landmark defense of extending substantial moral consideration to non-human animals (Singer, 9). Singer’s claim is striking. Not only does ‘speciesism’ sound like racism and sexism, forms of discrimination that are rightly condemned, Singer is telling us we’re complicit in form of discrimination that, were we to heed his advice not to use animals for pleasure and convenience, would dramatically change our day-to-day lives. 


In this article we’ll look at an argument Peter Singer gives for this claim. It says most humans are speciesists because we fail to acknowledge that species membership alone has no bearing on a being’s moral status, on how much moral consideration it’s owed.   


Speciesism Is Similar to Racism and Sexism

Mrs. H. Riordan, Suffragette, Bain News Service, date unknown. Source: Library of Congress, Bain Collection
Mrs. H. Riordan, Suffragette, Bain News Service, date unknown. Source: Library of Congress, Bain Collection


One of moral philosophy’s tasks is drawing borders around the moral community, the group of beings who deserve moral consideration. Everyone should agree on the easy cases. Sticks and stones are not moral community members, neither are dishwashers and spatulas; human beings are definitely members, and many would say the same about cats and dogs. Cases on the margins are trickier. If cats and dogs are moral community members, what about rodents and shellfish? And the environment? Is it a member of the moral community, something to which we have duties, say, of conservation? 


Assuming questions about moral membership can be settled, another task of moral philosophy ranks members’ interests. Even if dogs and cats are members of the moral community, for example, many would argue their interests weigh less than our own. Something similar might be argued about children: surely their interests do not in every circumstance weigh the same as adults’. These examples show that ranking interests in the moral community is unobjectionable. 

Get the latest articles delivered to your inbox

Sign up to our Free Weekly Newsletter


Another Form of Discrimination

roman bears animals in ancient rome
Roman Bear Mosaic, 4th century CE. Source: Getty Museum


But the same cannot be said of every way of ranking interests. Consider using race and sex. A sexist might believe that women should face higher standards because they are women; a racist might believe that the color of someone’s skin substantively indicates his fitness for a job. In each case a fact about a person—her sex, his race—is the basis on which moral matters of justice and dessert are decided. The problem is that neither fact is relevant to such matters. Biological sex justifies nothing about higher standards, and race justifies nothing about fitness for a job. Instead, each is an example of discrimination: using irrelevant facts about someone to decide what they are owed. 


Singer contends that speciesism is another form of discrimination. Species membership just isn’t a morally relevant property, he thinks, the type of thing that grounds an individual’s moral standing. Using species to rank interests—my interest in pleasure matters more than my cats’ just because I’m human, say—is therefore as mistaken as using sex or race. 


Let’s see why he thinks this is the case. 


Species Is Not a Morally Relevant Property

Landschap met hertenjacht, Egbert Jansz., after Antonio Tempesta, 1598. Source: Rijksmuseum
Landschap met hertenjacht, Egbert Jansz., after Antonio Tempesta, 1598. Source: Rijksmuseum


Singer believes that species is not a morally relevant property. Roughly, a property is morally relevant when a subject has certain interests in virtue of possessing it. So sentience is a morally relevant property because every sentient being has interests in pursuing pleasure and avoiding pain, and these interests typically attach to good/bad value judgments in ethics. Rationality is also a morally relevant property because every rational being can deliberate and assume responsibility for its actions, which are necessary to various ways of participating in the moral community. 


Singer wants to place species in the same group as race and sex, which we have seen are not morally relevant properties. But, unlike race and sex, species does reliably track some morally relevant capacities and interests: learning an animal is a cat suffices to know it can suffer but not use language; learning an animal is a human suffices to know it is typically capable of both. So, if speciesism is a prejudice at all, it is likely more entrenched even than racism and sexism because it is not a completely arbitrary basis for making moral decisions. It does tell us something about whether a subject likely has certain morally relevant interests. 


Our question becomes more pressing: where does Singer believe speciesism goes wrong? 


Speciesism is Grounded in Singer’s Principle of Equal Consideration of Interests

Origin of Species Title Page, John Murray, 1859
Origin of Species Title Page, John Murray, 1859. Source: Wikimedia Commons


Singer believes that speciesism falters when it is used to discount animals’ interests in avoiding pain in favor of humans’ interest in pursuing pleasure. This follows from his principle of equal consideration of interests


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 (Singer, 5; emphasis mine). 


The critical phrase in this principle is like interests. Singer is not arguing that every animal interest is morally on par with every human interest. He does not believe we should extend voting rights to marsupials or den rights to humans (Singer, 2). Instead, he believes that when the interests at stake are sufficiently similar, as human and non-human interests in avoiding pain and pursuing pleasure surely are, then species membership alone cannot be a basis for ranking human interests in avoiding pain above the same of animals. Assuming otherwise is speciesism, as this would be no different from assuming race or sex alone are legitimate bases for ranking interests. 


The Argument from Marginal Cases Reveals the Mistake of Speciesism

Mama I Love You, Erwin Bosman, 2006. Source: Wikimedia Commons
Mama I Love You, Erwin Bosman, 2006. Source: Wikimedia Commons


This sounds plausible enough: why should my pleasure take precedence over my cat’s pain? But Singer backs up this principle with a powerful argument commonly known as the argument from marginal cases. Scott Wilson, in his excellent article on animal ethics, presents the argument succinctly: 


  1. In order to conclude that all and only human beings deserve a full and equal moral status (and therefore that no animals deserve a full and equal moral status), there must be some [morally relevant] property P that all and only human beings have that can ground such a claim
  2. Any P that only human beings have is a property that (some) human beings lack (e.g., the marginal cases)
  3. Any P that all human beings have is a property that (most) animals have as well
  4. Therefore, there is no way to defend that claim that all and only human beings deserve a full and equal moral status


This argument shows that speciesism is wrong because it is arbitrary. Premise 1 says that if all humans, as a species, deserve higher moral status than all other animals, then humans must possess some morally relevant property—rationality, language, higher-order thought, whatever—that explains this. Meanwhile, premise 2 says not all humans will possess the property in question, for not all humans are developmentally identical. Premise 3 says that if another property, such as sentience, is offered to explain the moral status each and every human shares, then most non-human animals have this property as well. 


The upshot is that either not all humans have the same moral status, or humans and animals share moral status when similar interests are at stake. Speciesism, like racism and sexism, is a prejudice because it does not establish a principled boundary between animal and human interests.

Author Image

By Ryan AlexanderPhD PhilosophyRyan holds a PhD in philosophy