Modus ponens

Modus ponens is a valid, simple argument form:

If P, then Q.

P.

Therefore, Q.

Here is an example of an argument that fits the form modus ponens:

If love conquers all, then love conquers Attila the Hun.

Love conquers all.

Therefore, love conquers Attila the Hun.

Another example:

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

Democracy is the best system of government.

Therefore, everyone should vote.

Basically the idea is to make an "if-then" claim--these are called conditional claims--and then affirm the "if" part, or the antecedent, and then conclude with the "then" part, or the consequent.

In symbols:

  ( A → B )
  A        
  ∴ B

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See also: modus tollens.