The present paper is part of a larger project of investigating how far puzzling questions about Carnap's philosophical deflationism – as expressed most prominently in "Empricism, Semantics and Ontology"1 – can be answered by reference to his own preferred position in areas upon which this meta-philosophical position can be expected to have a bearing. For that project the explorations below provide a starting point; on the present occasion they will, I hope, be found to be of independent interest. At issue is the question of what makes Carnap's The Logical Structure of the World (the Aufbau) a pre-physicalist work.