Lecture 1/23/08

Lecture 1/23/08 - • Statement ϕ implies statement ψ iff...

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PHIL 10 – 1/23/08 Relations between two statements: equivalence, consistency, implication Two statements are equivalent iff they have identical truth columns To test for equivalence, construct a joint truth table for the two statements and compare truth columns Two statements are consistent iff it is possible for them to both be true at the same time To test for consistency, do a joint truth table for the two statements, if there is a row on which both statements are T, then they are consistent
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Unformatted text preview: • Statement ϕ implies statement ψ iff: if ϕ is true, then ψ must be true Counter example row, if ϕ is T and ψ is F • Equivalence A set of statements are equivalent if they all have identical truth problems • Consistency If there is at least one row where they are all true • Joint Implication A set of statements if ϕ is T and ψ is F • Argument Validity An argument is deductively valid iff the premises jointly imply the conclusion •...
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