Validity

:This article discusses validity in logic, for the term in the social sciences see validity (psychometric).

Related Topics:
Logic - Social sciences - Validity (psychometric)

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In a logical argument, the term validity is used to determine whether a form of an argument meets a certain set of standards to be deemed valid. An argument is said to be valid if, for every model (m), all premises are true in (m), then the conclusion is true in (m).

Related Topics:
Logical argument - Premises - Conclusion

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A formula of logic is said to be valid if it is true under every interpretation (also called structure or model). See also model theory or mathematical logic#technical reference.

Related Topics:
Formula - Model theory - Mathematical logic#technical reference

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The relation between the two notions is expressed by the deduction theorem and the resolution theorem.

Related Topics:
Deduction theorem - Resolution theorem

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A tautology, or tautologous formula, is truth functionally valid. Not all valid formulas of quantificational logic are tautologies. See also the truth table article.

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