Re: Help with a problem

On Thu, 24 Nov 2005 18:42:53 -0800, William Elliot
<marsh@xxxxxxxxxxxxxxxxxx> wrote:

Rules of the Hypothetical Syllogism

1) To posit the antecedent is to posit the consequent
2) to sublate the consequent is to sublate the antecedent

(Michael J. Mahony, Essentials of Formal Logic)

In modern language:

Assume a conditional holds.

1) If its antecedent holds, then its consequent holds
2) if the negation of its consequent holds, then the
negation of its antecedent holds.

(due to J. E. Lemmon, Beginning Logic)


F.

--
"I do tend to feel Hughes & Cresswell is a more authoritative
source than you." (D. Ullrich)
.

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