In predicate logicuniversal instantiation (UI, also called universal specification or universal elimination, and sometimes confused with Dictum de omni) is a validrule of inference from a truth about each member of a class of individuals to the truth about a particular individual of that class. It is generally given as a quantification rule for the universal quantifier but it can also be encoded in an axiom. It is one of the basic principles used in quantification theory.