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Logic  /  Logic 079  ·  Atom · ~20 seconds

Contradictories

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State

A and O are contradictories; so are E and I. Contradictories always have opposite truth values.

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If "All S are P" is true, "Some S are not P" is false — necessarily, and vice versa.

Watch for

This is the one square-of-opposition relation that survives every interpretation. The rest come with fine print.