Comparisons of capacity for welfare and moral status across species (Rethink Priorities)

Effective altruism aims to allocate resources so as to promote the most good in the world. To achieve the most efficient allocation of resources, we need to be able to compare interventions that target different species, including humans, cows, chickens, fish, lobsters, and many others.

Comparing cause areas and interventions that target different species requires a comparison in the moral value of different animals (including humans). Animals differ in their cognitive, emotional, social, behavioral, and neurological features, and these differences are potentially morally significant. According to many plausible philosophical theories, such differences affect (1) an animal’s capacity for welfare, which is the range of how good or bad an animal’s life can be, and/or (2) an animal’s moral status, which is the degree to which an animal’s welfare matters morally.

Theories of welfare are traditionally divided into three categories: (1) hedonistic theories, according to which welfare is the balance of experienced pleasure and pain, (2) desire-fulfillment theories, according to which welfare is the degree to which one’s desires are satisfied, and (3) objective list theories, according to which welfare is the extent to which one attains non-instrumental goods like happiness, virtue, wisdom, friendship, knowledge and love. Most plausible theories of welfare suggest differences in capacity for welfare among animals, though the exact differences and their magnitudes depend on the details of the theories and on various empirical facts.

A central question in the literature on moral status is whether moral status admits of degrees. The unitarian view, endorsed by the likes of Peter Singer, says ‘no.’ The hierarchical view, endorsed by the likes of Shelly Kagan, says ‘yes.’ If moral status admits of degrees, then the higher the status of a given animal, the more value there is in a given unit of welfare obtaining for that animal. Status-adjusted welfare, which is welfare weighted by the moral status of the animal for whom the welfare obtains, is a useful common currency both unitarians and hierarchists can use to frame debates.

Different theories entail different determinants of capacity for welfare and moral status, though there is some overlap among positions. According to most plausible views, differences in capacity for welfare and moral status are determined by some subset of differences in things like: intensity of valenced experiences, self-awareness, general intelligence, autonomy, long-term planning, communicative ability, affective complexity, self-governance, abstract thought, creativity, sociability, and normative evaluation.

Understanding differences in capacity for welfare and moral status could significantly affect the way we wish to allocate resources among interventions and cause areas. For instance, some groups of animals that exhibit tremendous diversity, such as fish or insects, are often treated as if all members of the group have the same moral status and capacity for welfare. Further investigation could compel us to prioritize some of the species in these groups over others. More generally, if further investigation suggested we have been overestimating the moral value of mammals or vertebrates compared to the rest of the animal kingdom, we might be compelled to redirect many resources to invertebrates or non-mammal vertebrates. To understand the importance of these considerations, we must first develop a broad conceptual framework for thinking about this issue.