 On the subject of ontology, Quine criticized Carnap’s use of quantifiers over intensional entities in Carnap’s intensional semantics. Closely related criticisms were voiced by many others, especially including Carnap’s own former Vienna colleague Otto Neurath and the Oxford philosopher Gilbert Ryle, whose review of Meaning and Necessity (Ryle 1949) was perhaps the nastiest and most vituperative review ever written of anything Carnap wrote. Carnap responded (calmly) with his well-known paper “Empiricism, Semantics, and Ontology” (1950a), in which he distinguished between two understandings of “existence” attributions, internal and external. Internal ones are framework-relative; they specify a language framework before claiming or denying or questioning the existence of a thing. External existence claims or questions lack such a relativization to a framework. For Carnap only internal questions make sense, if you take them literally. Thus “are there infinitely many numbers?” makes sense if you relativize it to a framework such as, for instance, Zermelo-Frankel set theory—which has an axiom of infinity, so the answer is (trivially) yes. But without such a relativization the question makes no sense to Carnap—unless, that is, you reinterpret it as a practical (normative) question of deciding among frameworks or explications. All of this applies, in particular, to the quantification over abstract entities in a framework for semantics, such as intensional semantics. In turn, Quine rejected Carnap’s internal/external distinction, which for Quine relied on the analytic/synthetic distinction, as accepting a framework would consist in accepting the sentences that are analytic in the framework. Whether the ontological internal/external distinction needs to build on the semantic analytic/synthetic distinction has itself become a topic in recent philosophical work on metaphysical deflationism about existence questions, which takes Carnap’s metaontological views as its historical starting point (see, e.g., Thomasson 2014; see the supplement  Tolerance, Metaphysics, and Meta-Ontology (Sections 2 and 3)  for further discussion). 