LPL_4.1_lecture

LPL_4.1_lecture - Tautologies and logical truth From our...

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Tautologies and logical truth From our discussion of logical consequence, we know that a sentence is a logical consequence of a given set of premises if it is impossible for the conclusion to be false when the premises are true. As we will see, some sentences will turn out to be logical consequences of any set of premises, even the empty set. In other words, some sentences will be true regardless of what premises are given, even if no premises are given. Such sentences are said to be logical truths because there are no circumstances in which they could possibly be false. a = a logical possibility vs. logical necessity A sentence is logically possible if, under some set of circumstances, it could be true on purely logical grounds. While physical laws prevent us from traveling faster than the speed of light, there are no such logical constraints upon this action. However, some sentences are not even logically possible. In such cases, the rules of logic prevent a sentence from being true, under any circumstances.
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This note was uploaded on 06/06/2011 for the course PHIL 110 taught by Professor ? during the Fall '06 term at South Carolina.

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LPL_4.1_lecture - Tautologies and logical truth From our...

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