Contractualist Theories of morality construe morality to be the set of rules that rational individuals would choose under certain specified conditions to govern their behavior in society. These theories have had a long and varied history; however, the relationship between contractualism and animals was not really explored until after John Rawls published his A Theory of Justice. In that work, Rawls argues for a conception of justice as fairness. Arguing against Utilitarian theories of justice, Rawls believes that the best conception of a just society is one in which the rules governing that society are rules that would be chosen by individuals from behind a veil of ignorance. The veil of ignorance is a hypothetical situation in which individuals do not know any particular details about themselves, such as their sex, age, race, intelligence, abilities, etc. However, these individuals do know general facts about human society, such as facts about psychology, economics, human motivation, etc. Rawls has his imagined contractors be largely self-interested; each person’s goal is to select the rules that will benefit them the most. Since they do not know who exactly they are, they will not choose rules that benefit any one individual, or segment of society, over another (since they may find themselves to be in the harmed group). Instead, they will choose rules that protect, first and foremost, rational, autonomous individuals.
Although Rawls argues for this conception as a conception of justice, others have tried to extend it to cover all of morality. For example, in The Animals Issue, Peter Carruthers argues for a conception of morality that is based largely on Rawls’s work. Carruthers notes that if we do so extend Rawls’s conception, animals will have no direct moral standing. Since the contractors are self-interested, but do not know who they are, they will accept rules that protect rational individuals. However, the contractors know enough about themselves to know that they are not animals. They will not adopt rules that give special protection to animals, therefore, since this would not further their self-interest. The result is that rational human beings will be directly protected, while animals will not.