The principle disadvantage of an entailment account as compared with a quantifier account is that it fails to provide a neutral platform for assessing the ontological costs of theories: disagreements over ontology will often reappear as disagreements over the existential entailments of a theory. Here it is important to distinguish two things that might be meant by “criterion of ontological commitment”. (This isn't always done; but Jackson (1989) and Rayo (2007) are clear on the distinction.) One might mean a test by which ontological commitments can be discovered. Or one might mean an analysis that says what ontological commitment consists in. An adequate test would be a procedure that could be applied by all parties in a neutral way, independently of those parties' prior ontological beliefs. Quine believed that the quantifier criterion provided such a test. He was aware, of course, that there would be disputes over how best to regiment theories within first-order logic. But—or so he thought—once theories were regimented, the quantifier criterion would supply unequivocal verdicts.