Quine's criterion of ontological commitment has dominated ontological discussion in analytic philosophy since the middle of the 20th century; it deserves to be called the orthodox view. For Quine, such a criterion played two distinct roles. First, it allowed one to measure the ontological cost of theories, an important component in deciding which theories to accept; it thus provided a partial foundation for theory choice.  Moreover, once one had settled on a total theory, it allowed one to determine which components of the theory were responsible for its ontological costs (see Quine (1960: 270) for the purported benefits of such ontological bookkeeping). Second, it played a polemical role. It could be used to argue that opponents' theories were more costly than the theorists admitted (see Church (1958), who wields the criterion polemically against Ayer, Pap, and Ryle). And it could be used to advance a traditional nominalist agenda because, as Quine saw it, ordinary subject-predicate sentences carry no ontological commitment to properties or universals.