Midterm: All Animals Are Equal? (89/100)

All Animals Are Equal?

Phil 23026 Animal Ethics

Nathan Laurell

November 6th, 2022


(3) In his paper, “All Animals Are Equal,” Peter Singer argues in favor of the following “principle of equality”: “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.” Assess Singer’s argument.

The Argument

The argument presented by Peter Singer in “All Animals Are Equal” comprises two parts. First, Singer defines who is worthy of (moral) consideration. Second, through the “principle of equality,” he outlines how we should think about, and act on, that consideration.

At the outset, it’s helpful to understand where Singer sits in the broader philosophical context: he is a utilitarian who draws on the work of Jeremy Bentham (specifically the concept of equality and the consideration of suffering).1 This leads him to frame his argument in terms of minimizing pain in the world, a tenet of utilitarianism. He starts with a universal rule that sounds an awful lot like a categorical imperative of sorts—all animals who suffer should be considered equally—but sets it within the utilitarian context of minimizing pain.

To begin his argument, Singer draws an expansive circle around all sentient animals. For him, sentience is defined by the ability to feel pleasure and pain, and it is this ability that gives rise to interests and thus consideration, or moral standing. He is interested in suffering and specifically the minimization of that suffering. For Singer, “suffering is not only necessary but sufficient to say a being has interests.”2 Singer would thus have us consider all animals who can suffer, from a field mouse to an eel to a human—they all have standing. This is an important distinction—it’s not rationality or self-consciousness but suffering that gives standing.

Singer then introduces the concept of the “principle of equality,” which states that we must equally consider the interests of all sentient animals. It is important to note here that what he requires is equal consideration—he does not require equal or identical treatment.3 He is saying all beings’ interests should be equally considered, not that all beings are in fact equal.4 For him, this means all beings receive equal treatment for equal types of suffering.

From here, he goes on to draw parallels to the way humans have discriminated against each other based on race or gender throughout history. He cites racism and sexism as wrongs founded on biological attributes and, arguing along the same lines, describes the judging of a being based solely on its species as speciesism, which is wrong in a similar way that racism and sexism are wrong.

To summarize, Singer uses a biological definition (sentience and, specifically, the capacity for suffering) to draw a large circle of moral standing that includes both humans and non-human animals. Further, he says that all beings within the circle require equal consideration, thus putting humans and non-human animals on the same moral plane, at least as it relates to suffering. And finally, by not considering them equally, we are committing speciesism, which is similar to racism and sexism.

For this paper, the words pain and suffering are used interchangeably. Also, Singer’s consideration will be understood as a form of moral standing. Sentient animals means beings who can suffer, including humans, and the circle of suffering describes all sentient animals that have standing (or, using Singer’s word, consideration). Lastly, the phrase future rationalizing describes the process whereby a self-conscious and sentient animal can critically think about its future, a capacity that, importantly as we will see, is variable among sentient animals.

The Premise

Starting with the circle of suffering, on what grounds could animals be excluded? If they don’t feel pain? What if they feel pain but differently than humans?

Regarding the first case, few people would argue that animals do not feel pain. Whether considered through a behavioral, physiological, or evolutionary lens, that animals feel pain seems hardly worth questioning. Behaviorally, they exhibit many of the same behaviors as humans when they’re in pain (they writhe and moan, their faces contort).5  In terms of physiology, their brains behave similarly to human brains, with many of the same compounds (dopamine and serotonin, for example). Lastly, from an evolutionary standpoint, the nervous system developed before the branches broke into reptiles, birds, and mammals, and thus we share a common evolutionary record. Therefore, it can be stated with a remarkably high degree of confidence that animals feel pain.

The second case is a bit more complicated. Different species may experience and process pain differently—we’re not biologically identical, after all—but should that matter? As a utilitarian, should Singer be more interested in exploring this? Perhaps there are different types of pain, based upon which a sort of pain index could be developed and used when assessing consideration. Or maybe the reality is we can never know what pain is like for, say, a bat, and if this is unknowable, how are we to equate their experience to ours?

But to argue any of this is to miss Singer’s point. In terms of consideration, the type or amount of pain does not matter; all that we need to believe is that the being feels pain. This is enough to include it in the circle of suffering. To distinguish types of pain would be like distinguishing between types of intelligence in deciding who can and cannot vote (a concept with which, sadly, history is not unfamiliar). We don’t deny voting rights—which in a way, is a right to be considered—based on variations in intelligence, and as such, we shouldn’t deny moral standing due to variations in pain perception. The only requirement is that they suffer, not in what way or how much. In fact, Singer says as much: “It is probably true that comparison of suffering between members of different species cannot be made precisely, but precision is not essential.”6 As an aside, it is possible, and likely probable, that non-rational sentient animals experience greater perceived pain than rational sentient animals in response to the same stimuli given that rational sentient animals often understand the how, why, and when of the pain—not knowing may make things even more painful.7

But one could also make a related objection. In his discussion of killing, Singer speaks of degrees of future rationalizing or desiring. The higher the capacity for future rationalizing, the more valuable a life, and thus the more harm done in extinguishing said life.8 Indeed, this is how Singer justifies killing a dog if one were forced to choose between killing a dog and killing a human—the human is capable of a higher degree of future rationalizing and thus is more worthy of saving.9 But why speak of a hierarchy in regards to killing different beings but treat them all equally when it comes to suffering? Why the double standard for killing versus suffering?

These objections to Singer erroneously conflate killing and suffering, however. This is where Singer’s argument is nuanced, and the nuance matters. He argues that all beings feel pain similarly, but all beings do not have the same capacity to think about the end of their lives (i.e., there are different degrees of future rationalizing). A good example is the one he gives: forced to choose between the life of a severely cognitively impaired adult and a normally functioning adult, most people would choose to save the latter’s life. But when faced with inflicting pain, many would feel that it’s at best equally unacceptable, if not in fact more so, to inflict pain on the cognitively impaired adult (which accords with the observation above that non-rational sentient animals may feel pain more acutely than those who can understand—i.e., rationalize—it).10 Thus, pain and killing are different, and conflating these concepts betrays a misunderstanding of what Singer deems to be equal.

Lastly, we should flag one other objection. There is a school of thought among some contractualists that obligations exist only between self-conscious rational beings. The idea is that there is a standard of mutual understanding (a degree of rationalism required) to have any moral obligation. Immanuel Kant thus framed our duties to animals as merely indirect (if we have a duty to them, it is only indirectly, as the direct duty is to their owners or ourselves), and T. M. Scanlon has argued a similar view.11 But we live in a society that protects all kinds of non- or sub-rational entities or beings: property, children, cognitively disabled individuals, etc.—we even extend legal personhood to corporations. It’s not hard to think of a multitude of scenarios where we may have a moral obligation to those who aren’t rational. For instance, if a baby were left on a stranger’s doorstep, few would argue that the stranger didn’t have some obligation to it—despite that baby not being able to enter into a contract—and not just to the child’s parents. Indeed, Singer intentionally does not speak of duties or obligations; they are not relevant to his argument.12 What matters is the minimization of suffering; whether this is based upon an indirect or direct duty or obligation, Singer does not care. Considered in this way, it seems hard to argue with Singer that a world with less suffering is not more moral.

At this point, all sentient animals are in our circle of suffering—they feel pain, even if their perception of pain might be different from ours. We’ve clarified the distinction between killing and suffering and addressed the objections from some contractualists. While Singer wouldn’t use the term rights, we can say that if sentient animals feel pain, they have a right to be considered. But what of the equality argument—do they really have the same rights as humans?

Consequences and Objections

Drawing a large circle of suffering with a wide variation of sentient animals within and saying all the members deserve equal consideration may be problematic, however. It leads to uncomfortable questions like, “Are you saying my two-year-old son is the same as a chimpanzee?” (No.) “That I should consider the pain inflicted on a salmon the same as the pain inflicted on my spouse?” (Yes.) Many people take the equality principle as a challenge to the sanctity of human life—humans are special (which has a certain “the earth is the center of the universe” feel to it, but I digress). The reality is, it’s a lot easier for people to make a leap from men to women (in the case of sexism) than it is from humans to salmon (in the case of speciesism). Cora Diamond, writing in 1978, agreed:

To argue as Singer and [Tom] Regan do, is not to give a defense of animals; it is to attack significance in human life. The Singer-Regan arguments amount to this: knee-jerk liberals on racism and sexism ought to be knee-jerk about cows and guinea-pigs; they certainly show how that can be done, not that it ought to be. 13

To intentionally poorly paraphrase this sentiment in today’s parlance, “I can’t believe you woke liberals hate the human race.” To which, poorly paraphrasing again, Singer would reply, “We’re all animals, and you’re a speciesist (i.e., a racist) if you can’t see it.” And things would devolve from there.

The problem here is we’re treading on dangerous ground with loaded words—we’re talking about animals, race, cognitively disabled individuals, and the value of human life. Emotions are bound to run high. But what the critics seem to miss is the nuance of the pain-versus-killing argument discussed above. Singer’s views on life (or killing) are much more nuanced and constructive than these critics would admit and have room for the idea that humans are in fact different from other sentient animals. Importantly, this difference derives from the fact that they are more future rationalizing and not simply because they are human (i.e., their species). While we still need to give equal consideration to all beings in the realm of pain, the spectrum is much different and more nuanced (in his view) when considering killing.

That being said, even Singer admits that at times it will be impossible to draw our circle such that it does not exclude some humans and include some animals. This is a consequence of the way he has defined the principle of equality. There is no way to draw a circle around just the humans in a given scenario without playing the speciesism card. Not surprisingly, this rubs many the wrong way. But are these objections rational? Or are they reactionary because our human supremacy has been challenged?

What the critics seem to be saying is there are times it is okay to be a speciesist (not that they admit this directly). We, by our nature, are self-preserving, family-preserving, and tribe-preserving creatures, and when any of these are threatened, it triggers an emotional reaction (e.g., “Don’t compare my son to a chimpanzee!”). But there are situations when this self-preservation is a good thing. For example, when you encounter a bear in the woods, and it’s you or the bear, no one would argue that it is wrong to kill the bear (including Singer). What Singer is asking us to do is to put our interests, specifically as it relates to suffering, on the same moral plane as the interests of all other sentient animals in the circle of suffering. While it may feel like we’re being asked to sacrifice something that is uniquely human or being compared to animals, what he’s really asking from us is a reciprocal suffering standard—to value sentient non-human animals’ pain (not their lives) the same as ours—which seems like a pretty fair ask.

Nonetheless, it’s worth posing the question if all of Singer’s talk of speciesism and its comparison to racism and sexism were necessary in the first place? Presumably, as a good utilitarian, he’d want to minimize suffering, and in that sense, the more persuasive—not just logical—the argument, the better. Why not just say suffering matters equally, and it would be wrong (or even irrational) to be inconsistent? His argument still holds—he didn’t need to make the jump to the sensationalist comparison. His choice of words risks putting readers on the defensive from the beginning, making it even harder to win them over, however valid the comparison.


Realistically speaking, we will never be confronted with the choice of delivering equal amounts of pain to two different sentient animals (let alone choosing between their lives: in all likelihood, we will never be on that boat choosing between the human and the dog). Rather than getting wrapped up in improbable scenarios or specific language, perhaps we should take a step back. Singer is asking us to take pain seriously, to recognize that pain is universal among sentient animals, to bring them into our circle of suffering, to give them equal consideration, and to conduct ourselves in a way that minimizes suffering. His argument is sound, even if some of the conclusions may make us uncomfortable. This discomfort is a call to reflect on the consequences of our actions and, on some level, to confront our willful blindness.

To call all non-human sentient animals’ pain equal to ours is by no means undermining what makes us human or them unique. We live on a planet with nearly eight million other animal species.14 Those species include dogs who can smell time15 and octopuses who can change their skin to match their environment16 (and who, it seems, may even punch fish for spite).17 There really are aliens among us. The animal kingdom is full of wonder that we can only hope to someday understand. They are the only other life we know of in the universe, and we share this planet together with them. Surely we should celebrate their differences, allow them to flourish, and not enslave them for our own desires or make choices that cause them to suffer. The least we owe them is equal consideration, and that would seem to me to be entirely human.


1. Jeremy Bentham,

An Introduction to the Principles of Morals and Legislation

(White Dog Publishing, 2010).

2. Peter Singer, Animal Liberation (Harper Collins, 2009), 8.

3. Singer, 2.

4. Singer, 5.

5. Singer, 11.

6. Singer, 16.

7. Rollin, B.E. (1985). Animal pain. In M.W. Fox & L.D. Mickley (Eds.), Advances in animal welfare science 1985 (pp. 91-106). Washington, DC: The Humane Society of the United States.

8. Peter Singer, Practical Ethics (Cambridge University Press, 2011), Chapter 4.

9. Tom Regan, The Dog in the Lifeboat: An Exchange (New York Review of Books, 1985).

10. Peter Singer, Animal Liberation, 20.

11. F.M. Kamm, Intricate Ethics (Oxford University Press, 2007), Chapter 7.

12. Peter Singer, Animal Liberation (Harper Collins, 2009), 8.

13. Cora Diamond, “Eating Meat and Eating People,” Philosophy, Vol. 53, No. 206 (Oct., 1978), pp. 465-479, Cambridge University Press.

14. Hannah Ritchie and Max Roser (2021) - "Biodiversity" Published online at OurWorldInData.org. Retrieved from: 'https://ourworldindata.org/biodiversity' [Online Resource].

15. Amanda Pachniewska, “Can Dogs Tell Time?,” Animal Cognition, October 12, 2016.

16. Harry Baker, “How do octopuses change color?,” Live Science, May 11, 2022.

17. Simon Spichak, “Octopuses sometimes punch fish out of spite,” Massive Science, January 20, 2021.