Modus ponens

if X implies Y, and X is true, then Y is true

Modus ponendo ponens [1] is a valid, simple argument form in classical logic sometimes referred to as affirming the antecedent or the law of detachment. It is closely related to another valid form of argument, modus tollens or denying the consequent.

Modus ponens is a very common rule of inference, and takes the following form:

If P, then Q.
Therefore, Q.[2]

Related pagesEdit


  1. Latin: mode that affirms by affirming. Stone, Jon R. (1996). Latin for the illiterati: exorcizing the ghosts of a dead language. London, UK: Routledge: 60.
  2. Jago, Mark (2007). Formal logic. Humanities-Ebooks LLP. ISBN 978-1-84760-041-7.