Should we treat non-human animals well because they have rights, interests, neither, or both?

Sarah Yu

According to philosopher Jeremy Bentham, the question of animal rights is not "Can they reason? Nor, can they talk? But, can they suffer?" (Sweet 19). This question reveals a fundamental truth. If suffering is the basis for moral consideration, then humanity's treatment of non-human animals requires reexamination.

Mary Shelley's Frankenstein presents this question through her creature, a being who possesses sentience yet is denied moral consideration. The creature observes: "It was as the ass and the lap-dog; yet surely the gentle ass, whose intentions were affectionate, although his manners were rude, deserved better treatment than blows and execration" (Shelley 84). Shelley's creature recognizes what humanity often refuses to acknowledge. Non-human animals possess the capacity to suffer, and therefore deserve ethical consideration.

What makes a being deserving of moral consideration? This essay argues that no morally relevant traits, such as sentience and the ability to suffer, exist exclusively in humans, and that any differences between humans and non-human animals are differences in degree rather than in kind. As a result, non-human animals ought to be granted the rights and interests afforded to humans. While granting such rights demands restructuring fundamental aspects of society, the shared capacity to suffer should persuade humanity to expand its circle of moral concern.

The foundation of this argument rests on sentience. Sentience is defined as the capacity to experience feelings and possess cognitive abilities, such as awareness and emotional reactions (Broom 19). Sentience manifests in the universal experiences of pleasure and pain. Humans implicitly recognize that life would be bleak and devoid of meaning without desirable experiences, which is why they seek joy and avoid suffering (Sayre-McCord 2001). The question, then, is whether non-human animals experience these same sensations.

Animals demonstrate behavioral and physiological responses that drive them to engage in behaviors that maximize happiness and survival (“Darwinian Hedonism and the Epidemic of Unhealthy Behavior”). Play behavior demonstrates that animals exercise agency and seek out intrinsically rewarding experiences; it is widespread in mammals and avian species in contexts that suggest enjoyment rather than necessity. Herring gulls will engage in aerial drop-catching games with non-food objects, particularly during favorable weather conditions. Rats run to the hand of a researcher, on average, four times as quickly to receive tickles to their bellies, which mimic natural play behavior, compared to simple strokes. Young chimps tested in the laboratory choose play over food, unless they are extremely hungry (Balcombe 09). These behaviors demonstrate that animals choose to engage in play not because it will help them survive, but because it is pleasurable. Since, for non-human animals, interests can be defined as factors that contribute to their well-being (“The Weight of Animal Interests”), and animals demonstrate preferences for desirable experiences, they possess interests that should be considered.

Sentience encompasses the ability to suffer. When hogs are led to slaughter, they squeal and thrash in desperation, their bodies displaying every physiological indicator of terror (MSPCA-Angell). Any assumption that these animals experience pain less intensely than humans is dubious at best. If a being reacts to pain by seeking to avoid it, that being has an interest in not suffering. And if that interest exists, it deserves moral consideration.

Philosopher Peter Singer argues that the capacity for suffering “is not just another characteristic like the capacity for language, or for higher mathematics,” but rather the only defensible boundary of moral concern (Singer 89). A stone, Singer explains, has no interests because it cannot suffer. A mouse, however, has a clear interest in not being tormented because torment causes suffering. This is why Singer concludes that suffering is the prerequisite for having interests at all: it is the condition that must be satisfied before interests can be discussed in any meaningful way (Singer 89). If suffering grants moral consideration, and non-human animals demonstrably suffer, then humanity's treatment of these beings demands justification.

Some philosophers argue that non-human animals may not experience pain in ways comparable to humans, suggesting that their neurological differences render their suffering less morally significant. However, these arguments rest on unprovable epistemic assumptions. Neuroanatomical structures associated with pain perception, including pathways and processing zones in the central nervous system, are shared by humans and vertebrates (Martínez-Burnes 21). While humanity can never know with absolute certainty what it is like to be an animal, epistemic modesty demands caution. If we cannot know whether animals deserve moral consideration, denying them rights risks perpetual moral harm. The responsible choice, therefore, is to grant protections to beings capable of suffering rather than gambling with their welfare.

Rights are defined as moral protections requiring others not to interfere with fundamental interests. For instance, moral protections can include but are not limited to a universal agreement to act against murder and assault, or to let one live (Markkula Center for Applied Ethics 10). Rights and protections are necessary to ensure that animals have their autonomy respected, their pleasure maximized, and their suffering minimized. Rights and protections are bestowed because doing so produces desirable outcomes. If animals have a right not to suffer unnecessarily, it creates a duty for humans not to cause suffering (Markkula Center for Applied Ethics 90). Granting rights and protections to non-human animals does not mean all pygmy goats would be granted the unconditional right to vote, in the same way that children are not. Rights and protections serve to maximize pleasure, minimize pain, and would need to be different for different beings. However, these rights must preserve their intended core purpose and be universally present, even if different in form.

Attempts to distinguish humans from non-human animals based on traits like rationality or language create arbitrary moral boundaries, and demonstrate differences in degree rather than kind. If one were to argue that non-human animals should not be granted the same rights and protections as humans, the burden would be on them to identify a trait that exists in humans but not in any other non-human animal. They would also have the responsibility of distinguishing why that trait is morally significant. The most common argument against granting animals rights and interests is that humans possess superior intelligence. However, moral considerations are already extended to human beings with cognitive differences. 

Consider Julia Tanner’s The Argument from Marginal Cases and the Slippery Slope Objection, which defines marginal humans as those with different mental capacities compared to ‘normal’ adult humans. Tanner challenges the argument that marginal humans are morally considerable, but animals are not. She cites Peter Carruthers, who argues that denying rights to humans with differing intellectual capabilities sends us down a “slippery slope,”  threatening the rights of all individuals. Carruthers explains that no distinct line exists between infants and adults, or between individuals with varying cognitive abilities. Consequently, restricting rights only to “rational actors” or “normal adults” creates the potential for moral harm, because doing so would justify the exploitation of the less-capable by the more capable on no other basis than their ability to do so. Rights, protections, and interests cannot exist in any meaningful sense if the bright line for who is entitled to them is arbitrary. Even if people cannot know for certain the degree or existence of a marginal human's suffering, granting rights and interests to beings that have the capacity to suffer avoids moral harm, intentional or otherwise.

Marginalized humans’ capacity to suffer means they ought to retain their rights and interests. This principle is clear, for instance, in the case of humans with severe Alzheimer’s disease who have lost their language and memory. People living with dementia and their caregivers have the right to be free from discrimination and the right to exercise legal capacity regardless of mental assessments (OHCHR 15). Despite having a differing degree of mental capacity, people with dementia still retain their legal rights and interests, even if not directly.

The same inclusion does not exist for non-human animals. If marginal humans retain moral value despite a difference in intellectual degree, denying moral considerations to animals with comparable or even superior traits is incoherent. Avian research demonstrates that birds show behavioral, neurophysiological, and anatomical evidence of consciousness. Evidence of near-human-like levels of consciousness has been most dramatically observed in African grey parrots. Magpies have been shown to exhibit distinct similarities to humans, great apes, dolphins, and elephants in studies of mirror self-recognition (Low 12). If animals exhibit capabilities equivalent to or superior to marginal humans, there is no moral justification to treat them differently. The cognitive abilities of humans and nonhuman animals represent a difference in degree rather than in kind and, therefore, cannot serve as the basis to deny rights and interests to non-human animals.

Why, then, do individuals reject the notion of granting rights and interests to non-human animals? The belief that humans have greater importance than other beings creates a bias that impedes humans' desire to grant rights and interests to non-human animals. Furthermore, we (humans) often view beings and objects as valuable when they address our needs. To fuel the widespread mass consumption of meat, our society tolerates the use of factory farms that confine animals in atrocious conditions. Globally, more than 100 billion animals are killed for meat and other animal products every year, amounting to hundreds of millions of animals every day (Ritchie 17). This mass infliction of suffering on non-human animals makes our anthropocentrism, or a human-centered understanding of the world, ever more apparent. We are prepared to end an animal’s life merely for our consumption.

Anthropocentrism prevents us from granting rights and interests to animals even when we are obliged to do so. The majority of human beings, especially those who live in industrialized urban societies, have little or no contact with animals outside of their pets and their meals. As Dr. Singer explains, in doing so, we treat non-human animals as means to our ends, existing solely to serve human purposes without accounting for their interests (Singer 89). Humans must recognize that non-human animals possess value in their own right, independent of their usefulness to humans.

From Frankenstein's creature to factory farm animals, sentient beings have suffered from humanity's failure to acknowledge their capacity for pain. The creature's plea that animals "deserved better treatment" must not fall on deaf ears (Shelley 84). Sentience is the foundation for moral consideration. Humanity's treatment of humans with cognitive differences reveals that intellectual capacity is not what grants moral worth. And human-centered biases continue to blind society to the arbitrary nature of species-based discrimination.

Granting non-human animals rights and interests demands that we challenge long-accepted structures of human society. Ethical farming, reconsideration of research practices, and eliminating the use of animals in the cosmetics industry are tangible steps toward creating sustainable, empathetic systems to coexist. Even if valuing animal rights and interests requires restructuring fundamental aspects of our society, our shared capacity to suffer should persuade us to expand our circle of concern. Granting animals' interests and rights does not diminish human value. Instead, it strengthens our morality by grounding it in defensible principles rather than arbitrary distinctions.