||Higher-order metaphysics uses the formal languages of higher-order logic to formulate metaphysical views and arguments. Depending on the particular higher-order language used, higher-order quantifiers are often used to express general claims for which one would otherwise have to rely on a plenitudinous ontology of propositions, properties, and relations. For example, saying in English that some relation satisfies the axioms of minimal mereology incurs a commitment to the existence of relations. In contrast, second-order logic allows one conjoin the axioms of minimal mereology, and then generalize with respect to parthood, by replacing the constant for parthood by a binary second-order variable and binding it with an existential quantifier. Some proponents of higher-order metaphysics claim that along these lines, higher-order logic allows one to improve upon ordinary talk of propositions, properties, and relations. Consequently, they adopt a primitivist approach to higher-order languages, on which their intended interpretation is not provided by any translation into informal language or formal model theory.