Speciesism is the idea that humans grant or deny moral consideration to other beings based solely on their species. The term draws a direct parallel to racism and sexism: just as those prejudices favor one group over another based on an arbitrary trait like skin color or sex, speciesism favors humans over all other animals simply because they aren’t human. The concept has shaped decades of debate in philosophy, law, and animal welfare policy.
Where the Term Came From
British psychologist Richard Ryder coined the word “speciesism” in a 1970 leaflet distributed in Oxford. He used it to describe the widespread assumption that humans are automatically entitled to use other animals however they see fit. The term gained far wider attention when philosopher Peter Singer adopted it in his 1975 book Animal Liberation, which laid out a systematic case against the concept and became one of the most influential works in modern ethics.
The Core Argument
Singer defined speciesism as an unjustified bias that favors one’s own species over every other. His reasoning starts with a principle borrowed from the utilitarian philosopher Jeremy Bentham: “Each to count for one and none for more than one.” In practical terms, that means the interests of every being affected by an action should be weighed equally, regardless of what kind of creature it is.
The key question, in this framework, isn’t whether an animal can reason or use language. It’s whether that animal can suffer. The capacity for suffering is what gives any being interests in the first place. A rock has no interest in not being kicked. A pig does. If a being can experience pain or pleasure, Singer argues, there is no moral justification for ignoring that experience just because the being belongs to a different species.
This doesn’t mean all species must receive identical treatment. Equal consideration of interests can lead to different treatment depending on the nature of the beings involved. A dog doesn’t need the right to vote, but it does have an interest in not being confined in pain. The principle is about weighing comparable interests equally, not about pretending all creatures have the same needs.
The Comparison to Racism and Sexism
The analogy to other forms of prejudice is central to the speciesism argument. Singer treats racism, sexism, and speciesism as structurally identical: in each case, a morally irrelevant characteristic (race, sex, species) is used to justify disregarding another being’s interests. If we accept that discriminating based on race is wrong because race has nothing to do with the capacity to suffer, the same logic applies to species membership.
Psychological research supports this connection. Studies have found a positive correlation between speciesist attitudes and other prejudicial attitudes, including racism, sexism, and homophobia. People who score higher on measures of speciesism tend to score higher on measures of other forms of bias, suggesting that similar psychological mechanisms may underlie all of them.
How Speciesism Shows Up in Practice
Critics point to several large-scale systems as institutional speciesism. Industrial animal agriculture is the most commonly cited example. Billions of animals are raised in confined, often unsanitary conditions for human consumption. In Brazil alone, 2024 saw record slaughter numbers: 6.46 billion chickens, 39.27 million cattle, and 57.86 million pigs, all in a single country in a single year.
Scientific testing is another frequent example. A 2020 study published in the journal Alternatives to Laboratory Animals estimated that roughly 192 million animals were used for scientific purposes worldwide in 2015, a figure that includes animals used in experiments, killed for tissue, and bred for laboratory use. Animals are also hunted for fur, kept in captivity for entertainment, and used to test cosmetic products.
One of the more psychologically revealing forms of speciesism is the inconsistency in how people treat different animal species. Research shows that meat-eaters attribute fewer mental capacities to animals they eat compared to animals they keep as pets. People generally recognize intelligence as a key factor in an animal’s moral status, but they selectively ignore this when the animal in question is part of their diet. In one study, participants acknowledged the intelligence of unfamiliar animals like tapirs but disregarded equivalent intelligence in pigs, the animal they actually consumed. The moral status of an animal, in practice, bends around cultural habits and personal convenience.
Arguments Against the Concept
Not everyone accepts that speciesism is a valid comparison to racism or sexism. One common counterargument is that the analogy breaks down because racism and sexism rest on false empirical claims (that one race or sex is inherently superior), while the preference for humans rests on real, observable differences. Philosopher Shelly Kagan has argued that favoring humans isn’t based on a factual error but on a justifiable moral intuition about the unique status of our own species.
A more traditional philosophical defense comes from the Kantian tradition, which ties moral status to “personhood,” a concept defined by the capacity for rational moral judgment. Because only humans can recognize moral claims, make promises, and hold responsibilities, this view holds that only humans are full members of the moral community. Animals, in this framework, aren’t owed direct moral duties. Kant himself acknowledged, however, that cruelty to animals was still wrong, not because of what it does to the animal, but because it damages the person’s own capacity for kindness toward other humans. Someone who is cruel to animals, he argued, becomes hardened in their dealings with people.
Others argue from a cognitive standpoint. Some philosophers contend that moral consideration should be based on cognitive capacities like reasoning, planning, and abstract thinking rather than on the narrower ability to feel pain. Under this view, a being’s capacity for complex thought could matter morally even if it doesn’t experience suffering in the way animals do.
Speciesism in the Legal System
The speciesism debate has moved into courtrooms, though with limited success so far. Over the past decade, animal rights organizations have filed lawsuits in U.S. state and federal courts seeking legal personhood for nonhuman animals, particularly great apes and elephants. These cases have used habeas corpus, a legal mechanism traditionally reserved for prisoners challenging the conditions of their confinement, to argue that certain animals are being unjustly detained in zoos and private ownership.
To date, no court in the United States has accepted this argument. Courts have consistently declined to include nonhuman animals within the legal definition of “person” or to extend them the rights and protections that humans receive. The legal system, for now, maintains a firm line between human and nonhuman status, though these cases continue to test and publicize that boundary.
Why the Debate Persists
Speciesism remains contentious because it forces a confrontation between deeply held moral intuitions and the logical consistency of ethical principles. Most people believe that animal cruelty is wrong. Most people also eat meat, wear leather, and benefit from medical research conducted on animals. The speciesism framework asks whether those positions can coexist, or whether the moral logic that condemns cruelty to a dog should also condemn what happens inside a slaughterhouse. Where someone lands on that question depends on whether they believe species membership is a morally relevant trait or just another arbitrary line drawn to protect the interests of the powerful.