## FANDOM

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Transposition is a valid argument form and rule of replacement of propositional logic that allows one to invert and then convert a material conditional. That is, if $P \to Q$ is a material conditional that is true, then we may infer $\lnot Q \to \lnot P$.

This rule of replacement could be represented symbolically as: $P \to Q \Leftrightarrow \lnot Q \to \lnot P$, where $\Leftrightarrow$ is a metalogical symbol meaning "can be replaced with".

Natural Deduction Transformation Rules
Rules of Transformation