/ob verr"zheuhn, -sheuhn/, n.
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."
[1840-50; < LL obversion- (s. of obversio) a turning toward, equiv. to obvers(us) (see OBVERSE) + -ion- -ION]

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      in syllogistic, or traditional, logic, transformation of a categorical proposition (q.v.), or statement, into a new proposition in which (1) the subject term is unchanged, (2) the predicate is replaced by its contradictory, and (3) the quality of the proposition is changed from affirmative to negative or vice versa. Thus the obverse of “Every man is mortal” is “No man is immortal.” Because the obverse of any categorical proposition is logically equivalent to it, obversion is a form of immediate inference. See also conversion.

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Universalium. 2010.

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  • Obversion — Ob*ver sion ([o^]b*v[ e]r sh[u^]n), n. [L. obversio a turning towards.] 1. The act of turning toward or downward. [1913 Webster] 2. (Logic) The act of immediate inference, by which we deny the opposite of anything which has been affirmed; as, all …   The Collaborative International Dictionary of English

  • obversion — [ɔbvɛʀsjɔ̃] n. f. ÉTYM. V. 1900; bas lat. obversio « action de tourner vers », de obversum; → Obvers. ❖ ♦ Log. Opération par laquelle on substitue son contradictoire au prédicat d une proposition …   Encyclopédie Universelle

  • obversion — [äb vʉr′shən, əbvʉr′shən; äb vʉr′zhən, əb vʉr′zhən] n. [LL obversio < L obversus: see OBVERSE] 1. the act of obverting 2. Logic the act of inferring the obverse …   English World dictionary

  • Obversion — In traditional logic, obversion is a type of immediate inference in which from a given proposition another proposition is inferred whose subject is the same as the original subject, whose predicate is the contradictory of the original predicate,… …   Wikipedia

  • obversion — ob•ver•sion [[t]ɒbˈvɜr ʒən, ʃən[/t]] n. 1) an act or instance of obverting 2) pho 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… …   From formal English to slang

  • obversion — /ɒbˈvɜʒən/ (say ob verzhuhn) noun 1. the act or result of obverting. 2. Logic a form of inference in which a negative proposition is inferred from an affirmative or an affirmative from a negative. {Late Latin obversiōn , stem of obversiō} …  

  • obversion — äbˈvərzhən, və̄zh , vəizh also shən noun ( s) Etymology: Late Latin obversion , obversio, from obversus (past participle of obvertere) + ion , io ion logic : the operation of immediate inference that gives the obverse …   Useful english dictionary

  • Obversión lógica — Una obversión lógica es una de las operaciones que la lógica clásica tradicional admitía como operación lógica. Consiste en la modificación del juicio aristotélico de forma que cambiando la cualidad del juicio, afirmativo negativo, y negando el… …   Wikipedia Español

  • obversion — É‘b vÉœrʃn /É’b vɜːʃn n. reversal; inversion …   English contemporary dictionary

  • obversion — ob·ver·sion …   English syllables

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