Question about Logic, Philosophy - Allen Stairs responds

An elementary precept of logic says that where there are two propositions, P and Q, there are four possible "truth values," P~Q, Q~P, P&Q, ~P~Q, where ~ means "not."   Do people ever apply this to
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An elementary precept of logic says that where there are two propositions, P and Q, there are four possible "truth values," P~Q, Q~P, P&Q, ~P~Q, where ~ means "not."   Do people ever apply this to pairs of philosophy propositions? For example, has anyone applied it to positive and negative liberty, or to equality of opportunity and equality of condition, or to just process and just outcome? On these topics I can find treatments of the first two truth values but none of the second two.   If this precept of logic is not applied, has anyone set out the reasons? Response from: Allen Stairs I'm not entirely sure I follow, but perhaps this will be of some use.Whether two propositions really have four possible combinations of truth values depends on the propositions. Non-philosophical examples make the point easier to follow. Suppose P is "Paula is Canadian" and Q is "Quincy is Australian." In this case, the two propositions are logically independent, and all four combinations P&Q,. . .

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