| 释义 |
contrapositive, a. and n.|ˌkɒntrəˈpɒzɪtɪv|
[f. L. contrāposit-, ppl. stem of contrāpōnĕre (see prec.) + -ive.]
A. adj. Of, belonging to, or produced by contraposition.
1870Jevons Elem. Logic (1880) 84 We may also prove the truth of the contrapositive proposition in this way. Ibid. 85 Contrapositive conversion cannot be applied to the particular propositions I and O at all.
B. n. Anything characterized by contraposition. In Logic, a contrapositive proposition.
1870Jevons Elem. Logic (1880) 302 Convert and show that the result is the contrapositive of the original. 1884― Stud. Deduct. Logic 43 The contrapositive of the proposition ‘all birds are bipeds’ will be ‘all that are not bipeds are not birds’. 1876Kennedy tr. Reuleaux' Kinem. Machinery 181 The hydraulic press forms the contra-positive of..the pulley-tackle, the pressure-organ water in the one being replaced by the tension-organ rope in the other.
Hence contraˈpositively adv.
1858A. De Morgan in Trans. Camb. Philos. Soc. X. 182 H is the rich fool; h any other person; H′ the rich friend; R rich, r not rich; W weak, w not weak; A badly advised, a not so; C unfavourably circumstanced, c not so. H))R[M,W(A,C)]; contrapositively, r, m(w,ac) ))h; or r,mw,mac) )h; but H′)) mac; whence H′))h; or H′)·(H. 1892Mind I. 244 It means: ‘Every year in which the English harvests are bad is a year in which American corn-dealers gain’; or contrapositively: ‘Every year in which American corn-dealers do not gain is a year in which the English harvests are not bad’. |