LPL_4.3_4.4_lecture

LPL_4.3_4.4_lecture - Logical and tautological consequence...

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Logical and tautological consequence Throughout the course we have been concerned with the notion of logical consequence. Revisiting some earlier concepts, An argument is valid if its conclusion is a logical consequence of its premises. A sentence is a logical truth if it is a logical consequence of any set of premises. Sentences are logically equivalent if they are logical consequences of one another In all these cases, a sentence is said to be a logical consequence of another sentence (or group of sentences) when the truth of latter implies the truth of the former. If A is a logical consequence of B, then wherever B is true, A will be true as well. Now we come to a special type of logical consequence called tautological consequence . A sentence is a tautological consequence of another sentence (or group of sentences) if it is a logical consequence of that sentence (or group of sentences) by virtue of its truth- functional connectives. As was true for tautological equivalence, truth tables may be used to test for tautological consequence. Suppose we want to know if A Β is a tautological consequence of A B. We first need to build a truth table.
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LPL_4.3_4.4_lecture - Logical and tautological consequence...

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