Proof

Probability

A priori

A posteriori

Inductive or empirical reasoning

Deductive or rational reasoning

A fallacy

Anselm (1033-1109)

Proslogion

Necessary existence

Gaunilo

Rene Descartes (1596-1650)

Innate ideas

Immanuel Kant (1724-1804)

Gottlob Frege (1848-1925)

A predicate

First order predicates

Second order predicates

Norman Malcolm (1911-1990)

Alvin Plantinga (1932- ).