relational logic the formal study of the properties of and operations on (binary) relations that was initiated by Peirce between 1870 and 1882. Thus, in relational logic, one might examine the formal properties of special kinds of relations, such as transitive relations, or asymmetrical ones, or orderings of certain types. Or the focus might be on various operations, such as that of forming the converse or relative product. Formal deductive systems used in such studies are generally known as calculi of relations. See also RELATIO. G.F.S.