In order to be able to observe the dictates of equal treatment and material equality, it must become apparent, first, who is to be treated equally with whom and is the subject of material equality, and, second, what these dictates mean and entail. In response to the first question, a moral value such as dignity may be said to be decisive, but this position is unproductive and obscure. My alternative focuses on a characteristic that those who seek to be treated equally themselves share in common: rationality. Two or more beings are invariably considered each other’s equals in regard to a characteristic; this is what basic equality means. Several characteristics are possible; I argue that rationality is a nonrandom characteristic. Rational beings should, then, treat other rational beings equally, but this is not a moral demand; rather, self-interest is decisive. This provides the basis for formal equality. It is difficult, by contrast, to determine at what point the demands of material equality are met, for ‘material equality’ may be interpreted in various ways, and even if one adheres to a strict interpretation, it must be acknowledged that this is compatible with conflicting perspectives, none of which is compelling.