Category:Modus Tollendo Ponens

This category contains pages concerning Modus Tollendo Ponens:

Modus tollendo ponens is a valid argument in types of logic dealing with disjunctions $\lor$ and negation $\neg$.

This includes propositional logic and predicate logic, and in particular natural deduction.

Proof Rule

$(1): \quad$ If we can conclude $\phi \lor \psi$, and we can also conclude $\neg \phi$, then we may infer $\psi$.

$(2): \quad$ If we can conclude $\phi \lor \psi$, and we can also conclude $\neg \psi$, then we may infer $\phi$.