Our statement is valid; we can prove that by contraposition.    From LearnThat.org. 

Conversion by contraposition cannot be applied to the ordinary.    From Wordnik.com.  [Deductive Logic] Reference

Condition (ii) ensures that the law of contraposition is valid.    From Wordnik.com.  [Connexive Logic] Reference

Conversion by contraposition may be said to rest on the following principle.    From Wordnik.com.  [Deductive Logic] Reference

Conversion by contraposition differs in several respects from conversion by negation.    From Wordnik.com.  [Deductive Logic] Reference

Solovay set out to prove the other, much more difficult, direction by contraposition.    From Wordnik.com.  [Provability Logic] Reference

But what is this but an immediate inference by contraposition, coming under the formula.    From Wordnik.com.  [Deductive Logic] Reference

These are the theory of the syllogism and the doctrines of contraposition and obversion.    From Wordnik.com.  [The Traditional Square of Opposition] Reference

Turner's approach avoids the problem of contraposition by giving causal relations the form.    From Wordnik.com.  [Logic and Artificial Intelligence] Reference

As applied to conjunctive propositions conversion by contraposition assumes the following forms.    From Wordnik.com.  [Deductive Logic] Reference

He includes the problematic principles of contraposition (which he calls "conversion by negation").    From Wordnik.com.  [The Traditional Square of Opposition] Reference

Verification is, or ought to be, more than the mere contraposition of viewpoints by opposing sources.    From Wordnik.com.  [It is our fault « BuzzMachine] Reference

These are Buridan's examples, used in the fourteenth century to show the invalidity of contraposition.    From Wordnik.com.  [The Traditional Square of Opposition] Reference

When has Sarah Palin spoken out on a foreign policy issue in contraposition, in opposition to her party?.    From Wordnik.com.  [CNN Transcript Sep 17, 2008] Reference

Some writers in the twelfth and thirteenth centuries adopted a principle called "conversion by contraposition.".    From Wordnik.com.  [The Traditional Square of Opposition] Reference

Note well: there is no "contrast or contraposition between the institutional dimension and the charismatic dimension.".    From Wordnik.com.  [The Pope's audience with Communion & Liberation] Reference

As applied to disjunctive propositions conversion by contraposition consists simply in transposing the two alternatives.    From Wordnik.com.  [Deductive Logic] Reference

This statement contemplates conversion by contraposition only in reference to the A proposition, to which the process has hitherto been confined.    From Wordnik.com.  [Deductive Logic] Reference

Conversion by contraposition may be complicated in appearance by the occurrence of a negative term in the subject or predicate or both, e.g. All not-A is B.. '.    From Wordnik.com.  [Deductive Logic] Reference

'No A is B.' No A is not-A 'stands alone among E propositions in admitting of full conversion by contraposition, and the form of that is the same after it as before.    From Wordnik.com.  [Deductive Logic] Reference

Thus while creationists assert “If religiously important, then scientifically important”; these atheists assert the contraposition - but it is a fallacy in either case.    From Wordnik.com.  [Kansas BOE Chair - It's either the evolution or the Bible, not both - The Panda's Thumb] Reference

In its unanalysed form conversion by contraposition may be defined generally as -- A form of conversion in which both subject and predicate are replaced by their contradictories.    From Wordnik.com.  [Deductive Logic] Reference

But then I should be more careful about using contraposition (or something like it)!.    From Wordnik.com.  [PEA Soup] Reference

(Œˆ Š¥ Œ‰) implies PA Š¢ Š¥, which is just the contraposition of Gödel's second incompleteness theorem.    From Wordnik.com.  [Provability Logic] Reference

In order to reassert, in an inverted form, the whole of what was affirmed in the proposition, All quadrupeds are warm-blooded, we must convert it by contraposition, thus.    From Wordnik.com.  [A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)] Reference

(i) disjunctive syllogism or (ii) modus ponens and contraposition, since it is easy to transform modus tollens arguments into ones employing the other forms of inference.    From Wordnik.com.  [Skepticism] Reference

In order to re-assert, in an inverted form, the whole of what was affirmed in the proposition, All quadrupeds are warm-blooded, we must convert it by contraposition, thus.    From Wordnik.com.  [A System Of Logic, Ratiocinative And Inductive] Reference

(contraposition); attach the negative particle to the predicate, and again convert.    From Wordnik.com.  [Logic Deductive and Inductive] Reference

Against Herbart and Fries, Bolzano must justify contraposition by means of a supplementary premise: From “all.    From Wordnik.com.  [Bolzano's Logic] Reference

(namely, the employment of contraposition without conversion), is valid in the case of the U proposition; and so also is simple conversion.    From Wordnik.com.  [Deductive Logic] Reference

I rely here on Ashworth 1974, 201 “ 02, who reports the most common themes in the context of post-medieval discussions of contraposition.    From Wordnik.com.  [The Traditional Square of Opposition] Reference

(3) Conversion by negation involves only two steps of immediate inference: conversion by contraposition three.    From Wordnik.com.  [Deductive Logic] Reference

(contraposition of indifference) p ‰» q.    From Wordnik.com.  [Preferences] Reference