Category:Modus Ponendo Tollens

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This category contains pages concerning Modus Ponendo Tollens:


Modus ponendo tollens is a valid argument in types of logic dealing with conjunctions $\land$ and negation $\neg$.

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


Proof Rule

$(1): \quad$ If we can conclude $\map \neg {\phi \land \psi}$, and we can also conclude $\phi$, then we may infer $\neg \psi$.
$(2): \quad$ If we can conclude $\map \neg {\phi \land \psi}$, and we can also conclude $\psi$, then we may infer $\neg \phi$.