This blog post examines the grounds for why humans should be recognized as equal beings, delving deeply into the differences between Rawls’ concept of moral personhood and Singer’s notion of the capacity for consideration of interests, and the debates they generate.
Equality, alongside freedom, has become a core ideology of modern society. Humans are considered equal regardless of factors like race or gender. But what does this statement—that all humans are equal—actually mean? And what is its basis? First, no one interprets this as absolute equality, meaning treating all humans identically in every respect. This is because humans possess different innate abilities and talents, which cannot be made completely identical. Absolute equality also conflicts with values like individuality and autonomy.
The demand for equality does not aim to regard all inequality as evil. Rather, its goal is to eliminate inequality that lacks sufficient justification. The principle of conditional equality, often termed the prohibition of unjustified discrimination, requires justification when differential treatment occurs. This means that if appropriate justification is provided, equal treatment may be denied to those belonging to a particular category, while differential treatment is permitted for those outside that category. What, then, are the criteria for classifying people into specific categories? This question immediately leads to the inquiry into the basis of equality.
The concept of equality presented in various modern human rights declarations understood equality among individuals as an innate natural right. However, this natural rights theory revealed various problems, such as what constitutes a natural right and how the existence of such a right can be self-evident. Consequently, Rawls sought to present a basis for human equality without relying on existing natural rights theory. He held that formal justice is realized when rules operate fairly and consistently, treating similar cases similarly. However, he judged that merely adhering to rules based on formal justice cannot guarantee justice. Because rules themselves can conflict with other ideals possessing higher moral authority, the content of the rules is crucial for ensuring substantive justice.
To explain the basis for human equality, Rawls introduced the concept of range properties. For example, points inside a circle share the same range property—they are all inside the circle—despite differing positions. Conversely, points inside and outside the circle possess different range properties, defined by the boundary line. Rawls proposes moral personhood as the range property that entitles individuals to equal treatment. A moral person is one capable of making moral appeals and of paying attention to such appeals. Any being possessing this capacity, even minimally, has the right to demand equal treatment. Here, the term “moral person” does not imply moral excellence; it is used as a concept contrasting with beings that are morally irrelevant.
However, questions may arise about whether a child meets the minimum criteria required to be a person. Regarding this, Rawls argues that the minimal requirement for constituting a moral person is potential capacity, not its actualization, and thus even a child is an equal being.
Singer criticizes this attempt by Rawls. He contends that the level of sensitivity to morality varies among humans, and if the capacity for moral personhood is so crucial, it is not clear why a moral hierarchy based on the degree of that capacity should not be established. He also points out that the question of where to set the minimum threshold for becoming an entity with equal rights remains problematic. Furthermore, according to the criteria proposed by Rawls, individuals who either never possessed moral capacity or permanently lost it would be denied moral status, which conflicts with the commonly understood concept of equality.
For these reasons, Singer proposes the principle of equal consideration of interests as the basis for equality. In his view, for an entity to have interests—that is, to have a stake—it must fundamentally possess the capacity to experience pain and pleasure. An entity possessing this capacity is an entity with a stake and thus becomes the subject of equal moral consideration. At this point, it is also possible to give greater consideration to entities with stronger stakes. Conversely, beings lacking this capacity cannot possess any preferences or interests and thus do not qualify as subjects of equal moral consideration. Singer’s argument, by pointing out the limitations of existing equality principles and demanding a reexamination of the moral status of diverse beings—including both human and nonhuman entities—continues to provide significant insights in contemporary ethics.
