 Carnap takes this approach to every linguistic framework, no matter whether it is a framework about physical, concrete things, or a framework about abstract entities such as numbers, properties, concepts, propositions, etc. For him, the pragmatic reasons for accepting a given linguistic framework are that it has explanatory power, unifies the explanation of disparate kinds of data and phenomena, expresses claims more efficiently, etc. And we often choose a framework for a particular explanatory purpose. We might therefore choose a framework with expressions about abstract entities to carry out an explication (i.e., an elucidation of concepts), or to develop a semantics for natural language. For Carnap, the choice between platonism or nominalism is not a legitimate one; both are inappropriate attempts to answer an external pseudo-question.