Square of opposition

1) In Aristotelian or traditional categorical logic, immediate inferences are made “around” the square of opposition: Contraries, Subcontraries, Contradictories, Subalternation, and Superalternation. 2) In modern categorical logic, immediate inferences are restricted to contradictories. (See also Immediate inference, Contraries, Subcontraries,Contradictories, Subalternation, and Superalternation.)