How are we to adjudicate among rival ontologies? Certainly the answer is not provided by the semantical formula "To be is to be the value of a variable"; this formula serves rather, conversely, in testing the conformity of a given remark or doctrine to a prior ontological standard.
Willard Van Orman Quine, Roger F. Gibson (2004). “Quintessence: Basic Readings from the Philosophy of W.V. Quine”, p.189, Harvard University Press
