existential generalization a rule of inference admissible in classical quantification theory. It allows one to infer an existentially quantified statement DxA from any instance A (a/x) of it. (Intuitively, it allows one to infer ‘There exists a liar’ from ‘Epimenides is a liar’.) It is equivalent to universal instantiation – the rule that allows one to infer any instance A (a/x) of a universally quantified statement ExA from ExA. (Intuitively, it allows one to infer ‘My car is valuable’ from ‘Everything is valuable’.) Both rules can also have equivalent formulations as axioms; then they are called specification (ExA / A (a/x)) and particularization ((A(a/x) / DxA)). All of these equivalent principles are denied by free logic, which only admits weakened versions of them. In the case of existential generalization, the weakened version is: infer DxA from A(a/x) & E!a. (Intuitively: infer ‘There exists a liar’ from ‘Epimenides is a liar and Epimenides exists’.) See also EXISTENTIAL INSTANTIATION, FORMAL LOGIC , FREE LOGIC , UNIVERSAL INSTANTIA – TIO. E.Ben.