This paper examines the evolution of the understanding of the category of «equality» since ancient Rome to contemporary period. Analyzed the opinions of scholars of different ages with respect to formal and social equality. It is concluded that the claims of equality means the person, its requirement that society and the state gave it to any member not less benefits than others. However, the law of equality is the opposite assertion another law – the variability of natural human abilities, which makes people different, different from each other.