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[[pl:Modus ponens]] [[sv:Modus ponens]] 

'''Modus ponens''' ([[Latin]]: ''mode that affirms'') is a [[validity|valid]], simple [[argument form]]:

:If P, then Q.
:P.
:Therefore, Q.

or in [[logical operator]] notation:
:<math> p \rightarrow q </math>
:<math> \vdash p, </math>
:<math> \vdash q </math>
where <math>\vdash</math> represents the [[logical assertion]].

The argument form has two premises. The first premise is the "if-then" or ''conditional'' claim, namely that P implies Q. The second premise is that P, the ''antecedent'' of the conditional claim, is true. From these two premises it can be logically concluded that Q, the ''consequent'' of the conditional claim, must be true as well.

Here is an example of an argument that fits the form <i>modus</i> <i>ponens</i>:

:If democracy is the best system of government, then everyone should vote.
:Democracy is the best system of government.
:Therefore, everyone should vote.

For an amusing dialog that problematizes modus ponens, see [[Lewis Carroll]]'s "[[What the Tortoise Said to Achilles]]".

See also: [[modus tollens]], [[affirming the consequent]], [[Denying the antecedent]].

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====References====
* Adapted from the [[Wikipedia]] article, "Modus_ponens" [http://en.wikipedia.org/wiki/Modus_ponens http://en.wikipedia.org/wiki/Modus_ponens], used under the [[GNU Free Documentation License]]