contraposition

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con·tra·po·si·tion

 (kŏn′trə-pə-zĭsh′ən)
n.
An opposite position; antithesis.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

contraposition

(ˌkɒntrəpəˈzɪʃən)
n
1. the act of placing opposite or against, esp in contrast or antithesis
2. (Logic) logic the derivation of the contrapositive of a given categorial proposition
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

con•tra•po•si•tion

(ˌkɒn trə pəˈzɪʃ ən)

n.
1. placement opposite or against.
2. opposition or antithesis.
3. the inference drawn from a proposition by negating its terms and changing their order, as by inferring “not B implies not A” from “A implies B.”
[1545–55; < Late Latin]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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contraposition

noun
The American Heritage® Roget's Thesaurus. Copyright © 2013, 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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References in periodicals archive ?
His masterful hypotheticals and contrapositives demonstrate just how much the Court has achieved and how much we may now take for granted.
The most they can usually achieve is to convince people who love logic but hate contrapositives. (5)
(5) The contrapositive of "If A, then B" is "If not-B, then not-A." A fundamental principle of logic is that if an inference is valid, so is its contrapositive.