2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/75501This note analyzes in terms of categorial proof theory some standard assumptions about negation in the absence of any other connective. It is shown that the assumptions for an involutive negation, like classical negation, make a kind of adjoint situation, which is named involutive adjunction. The notion of involutive adjunction amounts in a precise sense to adjunction where an endofunctor is adjoint to itself.10 pagesLogicCategory Theory03F03; 03F07; 18A15; 18A40text