Let “explanationism” be the view that ontology is fundamentally an explanatory enterprise. What it does is “on a par” with natural science, as Quine put it. Carnap appears to offer a “lighter weight” alternative in “Empiricism, Semantics, and Ontology”: ontology is concerned with semantics and language choice. This paper argues that Carnap’s account of the internal/external distinction is of less use than Carnap suggests for diagnosis of disputes in ontology. But he largely agrees with Quine about explanationism. I propose that (...) explanationism is an attractive metametaphysical position between “heavy weight” and “light weight” views. Its method is abductive inference, which is broader than “light weight” methods. Since it is “on a par” with natural science, ontology contributes nothing beyond the claim that what there is, is what our best theories say there is. Hence, it is not “heavy weight”. (shrink)