Ontological Commitment

Ontological Commitment

In the philosophy of language and metaphysics, the ontological commitments of a theory (or sentence) are those things which must exist for the theory or sentence to be true. In other words, the ontological commitments of a theory are those entities whose existence is necessitated, presupposed, or implied by the theory. An expression or form of words is described as “ontologically committing” if a use of that expression in a declarative sentence adds to the ontological commitments associated with that sentence.

There is considerable debate about which elements of language are ontologically committing. Quine (the originator of the term “ontological commitment”) argued that the only ontologically committing expressions are variables bound by a first-order existential quantifier, and natural language expressions which were formalized using variables bound by first-order existential quantifiers. However, attempts have been made to argue that predicates are also ontologically committing, and thus that subject-predicate sentences bear additional ontological commitment to abstract objects such as universals, sets, or classes. Additionally, it has been suggested that the use of meaningful names in nonexistence statements such as “Pegasus does not exist” brings with it an ontological commitment to fictional objects.