First Notions of Logic: Preparatory to the Study of Geometry (Classic Reprint) - Softcover

Augustus De Morgan

 
9781330229590: First Notions of Logic: Preparatory to the Study of Geometry (Classic Reprint)

Synopsis

Excerpt from First Notions of Logic<br/><br/>Moreover, the negative words not, no, &c., have two kinds of mean ing which must be carefully distinguished. Sometimes they deny, and nothing more: sometimes they are used to affirm the direct contrary. In cases which ofi'er but two alternatives, one of which is necessary, these amount to the same thing, since the denial of one, and the affirm ation of the other, are obviously equivalent propositions. In many idioms of conversation, the negative implies affirmation of the contrary in cases which offer not only alternatives, but degrees of alternatives. Thus, to the question, Is he tall?' the simple answer, No,' most frequently means that he is the contrary of tall, or considerably under the average] But it must be remembered, that, in all logical reasoning, the negation is simply negation, and nothing more, never implying affirmation of the contrary.

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