Peter Singer: The Most Influential Living Philosopher

Australian philosopher Peter Singer is widely considered “the world’s most influential living philosopher.” A proponent of utilitarian ethics, Singer earned this title through his contributions to the modern animal rights movement and the philanthropic social movement known as effective altruism. In this piece, we’ll dive into the core arguments of his book “Animal Liberation” (1975)—often called the bible of the animal rights movement—and explore his ideas on effective altruism.

Who is Peter Singer?

Born in Melbourne, Australia, in 1946, Peter Singer graduated from the University of Melbourne in 1967 with degrees in history and philosophy, later earning his master’s there before completing his PhD at Oxford. After serving as a professor of bioethics at Princeton University for roughly 25 years, he now continues his writing and research from his home in Melbourne. Focusing on applied ethics, Singer has published groundbreaking works on topics like bioethics, global hunger, poverty, and animal rights. Staying true to his philosophical convictions, he is the founder of Animals Australia and a co-founder of the organization The Life You Can Save.

Animal Liberation: All Animals Are Equal

In the history of philosophy, the moral status of non-human animals has often been ignored or relegated to a position inferior to humans. To justify this, thinkers have frequently pointed to specific cognitive or social skills unique to our species. Published in 1975, Animal Liberation provides a fresh inquiry into our moral obligations toward non-human animals through a utilitarian lens.

Traditionally, utilitarianism is an ethical theory that measures the rightness or goodness of an action by how much happiness it generates for the greatest number of people. Under this framework, happiness is considered inherently good, while pain and suffering are viewed as bad. Therefore, the goal is to increase happiness and minimize suffering. In his book, Singer argues for extending this ethical framework beyond humans to encompass all sentient beings.

Singer’s core argument can be summarized as follows: The principle of equal consideration that we accept for humans should also be applied to non-human animals. The equality mentioned here does not refer to any factual equivalence between individuals, but rather serves as a moral guide for how we ought to treat them. This principle doesn’t mean we must treat everyone exactly the same, but rather that we must give equal weight to their needs and interests.

For Singer, the necessary criterion for a being to be worthy of equal consideration is sentience—the capacity to feel pain or pleasure. Sentience is the prerequisite for having interests at all (Singer, 2005, p. 54). For example, saying it is “not in a stone’s interest” to be kicked is morally meaningless because a stone lacks sentience. However, we can say it is against a dog’s interest to be kicked, because a dog is a creature capable of feeling pain.

In this context, Singer argues that the principle of equal consideration requires us to give equal weight to the interests of all beings who experience pain or pleasure to a similar degree.

Suffering to a Similar Degree

So, what do we mean by “suffering to a similar degree”? Let’s look at an example from Singer’s book. If you give a baby a sharp slap, you will likely cause them significant pain. To make a horse feel a comparable amount of pain, you would have to cause more severe damage—perhaps striking it with a stick. This is what Singer means by a similar amount of pain. While it is difficult to precisely compare the pain experienced by different species, Singer argues that even when we can’t make exact comparisons, we can still prevent the vast majority of the suffering endured by non-human animals. We can do this by focusing on situations where human interests are clearly not as significantly affected as the animals’ interests. This suggests we need to make sweeping changes—not just in our diets and clothing choices, but also in our entertainment, such as hunting, zoos, and circuses. Just as we view it as morally wrong to inflict unnecessary pain on a baby, we must view inflicting unnecessary pain on a non-human animal as equally wrong.

According to Singer, to deny this is to be “speciesist.” Singer defines speciesism as “a prejudice or attitude of bias in favor of the interests of members of one’s own species and against those of members of other species.” (Singer, 2005, p. 53). Like racism and sexism, speciesism violates the fundamental principle of equality. Rejecting speciesism means refusing to value a being’s pain more or less based on their biological species. However, opposing speciesism does not mean saying all lives have equal value. For Singer, qualities such as self-awareness, the ability to make plans for the future, and the capacity to form meaningful relationships are important when determining the value of a life. Acknowledging these qualities doesn’t contradict the rejection of speciesism. What matters is recognizing that the right to life isn’t exclusive to humans. Under this view, the lives of some non-human animals might be more valuable than the lives of some humans. For instance, a chimpanzee may possess more “human-like” qualities than an individual with advanced dementia or someone who has lost most of their cognitive functions. In such a scenario, if forced to make a choice, we would have to say the chimpanzee’s life is more valuable.

Effective Altruism

The philosophical foundations of effective altruism—both a philosophical approach and a social movement—stem from Peter Singer’s 1972 essay, Famine, Affluence and Morality. Singer wrote this during the 1971 East Pakistan (Bangladesh) genocide, a time when millions faced dire crises regarding hunger, shelter, and medical care. Observing that neither individuals nor governments were providing sufficient aid, Singer proposed this moral principle: “If it is in our power to prevent something bad from happening, without thereby sacrificing anything of comparable moral importance, we ought, morally, to do it.” (Singer, 1972, p. 231)

To understand this principle, look at the classic example from his essay: Suppose you are walking through a park and see a small child drowning in a pond. Would you try to save the child, even at the cost of ruining your clothes? I am certain that an overwhelming majority would say they would try to save the child, because our moral intuition tells us that a child’s life is infinitely more important than a pair of ruined clothes.

Peter Singer’s Deductions

Singer draws three important conclusions from this moral principle.

First, our moral obligations are independent of physical distance. There is no moral difference between helping a starving neighbor and helping people dying of hunger in Gaza. In both cases, helping is our moral duty.

Second, every individual has a responsibility to help, regardless of how many other people are also in a position to help. The fact that others are nearby and capable of saving the drowning child does not lessen your personal responsibility to act.

Finally, the traditional distinction between duty and charity needs to be questioned. Usually, helping people in need or donating to charity is seen as an act of generosity. We don’t typically say someone who spends their money on a lavish lifestyle is failing their moral duties. Yet, according to Singer, choosing to spend money on luxuries instead of helping those in need is a failure to fulfill a moral obligation.

These ideas form the bedrock of effective altruism, but the movement goes much further.

For Singer, effective altruism is built on the core idea that “we should do the most good we can.” Simply following universal moral codes—like not lying, killing, or cheating—is not enough to live a truly moral life. Once a person has provided for their own basic needs and those of their dependents, they should use their remaining resources—money, time, and skills—to make the world a better place. In this sense, effective altruism is not limited to just donating money. Spreading the word, donating blood, or registering as an organ donor are all parts of the movement.

While there isn’t total consensus among effective altruists on exactly “what constitutes the highest good,” the shared principle is that less suffering and more happiness is better. Furthermore, all beings who experience pain and pleasure matter. There are various research organizations and websites available to ensure that effective altruists are doing the most they possibly can. For example, GiveWell and The Life You Can Save are among the sites where people can find the most effective ways to use their donations.

Peter Singer has his fair share of supporters and critics, of course. But you know, in philosophy, the questions asked are often more valuable than the conclusions reached. Every question knocks on the door of another inquiry. In that sense, I believe the questions Singer raises are incredibly important. His inquiry into the moral status of non-human animals allows us to develop new perspectives on what it means to be human. Meanwhile, his views on philanthropy force us to reflect on our concepts of “needs” versus “wants” in this age of consumerist frenzy. And so many more questions remain… Stay curious!

References and Further Reading

Boesch, B. (2021, March 5). Ethics and absolute poverty: Peter Singer and effective altruism. 1000-Word Philosophy. https://1000wordphilosophy.com/2021/03/05/ethics-and-absolute-poverty/#_ftn6

Duignan, B. (2007, March). Peter Singer. Encyclopædia Britannica. https://www.britannica.com/biography/Peter-Singer

Hampton, L. (2023). Peter Singer. In R. Y. Chappell, D. Meissner, & W. MacAskill (Eds.), Introduction to utilitarianism. https://www.utilitarianism.net/utilitarian-thinker/peter-singer

Singer, P. (2005). Animal Liberation. (Original work published 1975)

Singer, P. (1972). Famine, Affluence, and Morality. Philosophy & Public Affairs, 1(3), 229–243. http://www.jstor.org/stable/2265052

Singer, P. (n.d.). About Peter Singer. petersinger.info. https://www.petersinger.info/about

The logic of effective altruism. (2015, June 1). Boston Review. https://www.bostonreview.net/forum/peter-singer-logic-effective-altruism/

YouTube. (2013, May 20). Peter Singer: The why and how of effective altruism. YouTube. Peter Singer: The why and how of effective altruism

Originally published in Turkish at Doğa Filozofu.