» For contraposition in the field of traditional logic, see Contraposition (traditional logic).: For contraposition in the field of symbolic logic, see Transposition (logic). In propositional logic, contraposition is a logical relationship between two propositions of material implication. A proposition Q (for example "Socrates is human") is materially implicated by a proposition P (for example "Socrates is a man") when the following relationship holds: » (P o Q) In vernacular terms, this states… (More on Contraposition)