Universal Instantiation is a rule of inference
in propositional logic
(∀xP(x) ^ (c ∈ U)) -> P(c)
If P(x) is true for all x and c is an element of the universe of discourse, P(c) is true.
If all men are mortal and Socrates is a man, Socrates is mortal.
See also: Universal Generalization, Existential Instantiation, Existential Generalization.