The paper applies formal logical semantics to analysis of empirical theories and scientific realism. Empirical theories are ordered sets of propositions and, under the assumption of consistency, they have models. On the other hand, semantic models as abstract algebraic structures. cannot be regarded as parts of the real world. In order to define links between theories, their models (understood as mediators) and the real world, the concept of empirical valuation is introduced. This innovation allows to base scientific realism on the semantic theory of truth.