 Carnap, Rudolf |  existence |  Frege, Gottlob |  grounding, metaphysical |  logical consequence |  logic and ontology |  logicism and neologicism |  Meinong, Alexius |  modality: varieties of |  nominalism: in metaphysics |  -->ontology--> |  possible worlds |  properties |  propositions |  quantifiers and quantification |  Quine, Willard Van Orman |  realism |  states of affairs |  tropes |  truthmakers 