Full Idea
Existential Generalization (or 'proof by example'): From P(t), where t is an appropriate term, we may conclude ∃xP(x).
Gist of Idea
Existential Generalization (or 'proof by example'): if we can say P(t), then we can say something is P
Source
Robert S. Wolf (A Tour through Mathematical Logic [2005], 1.3)
Book Reference
Wolf,Robert S.: 'A Tour Through Mathematical Logic' [Carus Maths Monographs 2005], p.20
A Reaction
It is amazing how often this vacuous-sounding principles finds itself being employed in discussions of ontology, but I don't quite understand why.