The paper makes some theoretical contributions, regarding the concept of the theory of rightness. In the first part, several scientific concepts are identified and defined as elements that belong to the theory of rightness as fairness. The second part of the paper analyzes the logical relations between rightness and justice, affirming and arguing that rightness is the state of a social system in which the natural right is verified, and justice is the state of a social system in which positive right is verified. Finally, the concept of the theory of rightness is defined logically, epistemologically and methodologically.