In “Empiricism, Semantics, and Ontology” Carnap drew his famous distinction between ‘internal’ and ‘external’ questions of existence, pronouncing the former meaningful and the latter meaningless. In The Significance of Philosophical Scepticism, Barry Stroud understands Carnap to be applying the verification criterion of meaningfulness in order to refute Cartesian skepticism. I suggest that Stroud misrepresents both Carnap’s aim and method. Carnap was responding to critics who suggested that his willingness to quantify over abstract entities in his work in semantics violated his commitment to empiricism. He rejected that criticism as presupposing a super-scientific standpoint from which constraints on the admissible domain of entities of science could be delivered. Carnap wanted to insulate science from the imposition of frrst-philosophical metaphysical prejudice, not to defuse scepticism by appeal to verificationism.