obversion

American  

[ob-vur-zhuhn, -shuhn] / ɒbˈvɜr ʒən, -ʃən /

noun

1. an act or instance of obverting.

2. something that is obverted.

3. 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.”

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Etymology

Origin of obversion

1840–50; < Late Latin obversiōn- (stem of obversiō ) a turning toward, equivalent to obvers ( us ) ( see obverse) + -iōn- -ion

Example Sentences

Dr. Bain calls this Material Obversion because it cannot be practised safely without reference to the matter of the proposition.

From Logic, Inductive and Deductive by Minto, William

Dr. Bain includes also Material Obversion, the analogue of Formal Obversion applied to a Subject.

From Logic, Inductive and Deductive by Minto, William

Define Obversion and Inversion, and apply these processes also to the above three propositions.

From Logic Deductive and Inductive by Read, Carveth

Under the general title of Immediate Inference Logicians discuss three subjects, namely, Opposition, Conversion, and Obversion; to which some writers add other forms, such as Whole and Part in Connotation, Contraposition, Inversion, etc.

From Logic Deductive and Inductive by Read, Carveth

Thus in Obversion and Conversion by Contraposition, the homogeneity of the negative term is tacitly assumed; it is assumed that A and not-A are of the same kind.

From Logic, Inductive and Deductive by Minto, William