The Ethical Treatment of Animals: The Moral Significance of Darwin’s Theory

Abstract

Although Darwin’s theory is not a moral theory, it is not morally insignificant. In this paper, I consider one area of ethics in which Darwin’s theory has a real impact: the ethical treatment of animals. Peter Singer characterises speciesism as the discrimination between different animals (favouring humans) solely on the grounds of species membership (rather than morally relevant considerations such as sentience and self-awareness). In response, a number of Singer’s opponents have embraced speciesism. Carl Cohen, for example, states “I am a speciesist. Speciesism is not merely plausible, it is essential for right conduct.” In this paper, I argue that a proper understanding of evolution poses serious problems for those who want to oppose Singer in this way. Moral status is transitive and sortal: if A has the same moral status as B and B has the same moral status as C, then A and C must also have the same moral status. But species membership is (on standard definitions) non-transitive. Dawkins states that “Non-interbreeding is the recognised criterion for whether two populations deserve distinct species names.” According to this (and most other definitions of “species”) if A is the same species as B and B is the same species as C, it is not the case that A and C must be the same species. (A could interbreed with B but not C). It is only the fact that most intermediates have died out that gives the impression of distinct species (and gives the impression of transitivity).