The rationality theorem is a theory introduced by political scientist Graham Allison in his book, Essence of Decision: Explaining the Cuban Missile Crisis. His definition of the rationality theorem states:

There exists no pattern of activity for which an imaginative analyst cannot write a large number of objective functions such that the pattern of activity maximizes each function.

Allison uses the theorem to attack any social science analysis that assumes a measure of rationality on the part of the actors.