E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
An argument a posteriori is one from effects to cause. Thus, to prove the existence of God a posteriori, we take the works of creation and show how they manifest power, wisdom, goodness, and so on; and then we claim the inference that the maker of these things is powerful, wise, and good. Robinson Crusoe found the footprints of a man on the sand, and inferred that there must be a man on the island besides himself. (See PRIORI.)