obversion

/ob-vur-zhuhn, -shuhn/US // ɒbˈvɜr ʒən, -ʃən //

厌恶,厌恶感,厌恶症,厌恶性

Definitions

n.名词 noun

1
- : an act or instance of obverting.
- : something that is obverted.
- : Logic. a form of inference in which a negative proposition is obtained from an affirmative, or vice versa, as “None of us is immortal” is obtained by obversion from “All of us are mortal.”

Dr. Bain calls this Material Obversion because it cannot be practised safely without reference to the matter of the proposition.
In this it differs from Obversion, Conversion, and Contraposition, each of which stands for one process.
Define Obversion and Inversion, and apply these processes also to the above three propositions.
A further process, known as Contraposition or Conversion by Negation, consists of conversion following on obversion.