One should not commit to metaphysical necessity; semantic modalities are enough. The best approaches to elucidate semantic modalities are versions of linguistic ersatzism and fictionalism, even if only developed in parts. Within these necessary properties and the difference between natural and semantic laws can be accounted for. The proper background theory for this is an updated version of Logical Empiricism. The anti-metaphysical attitude of Logical Empiricism deserves revitalization. The second part of the book illustrates a methodological observation from the first part: elucidating a concept can proceed by computational modelling. As an example, the book concerns modelling belief dynamics in the sense of building a computational model. The purpose is to illustrate some ideas about belief changes in a web of beliefs to explore and deepen one's understanding of belief changes by implementing corresponding algorithms. As a part of the model accepting conditionals and counterfactuals can be understood by versions of Ramsey Tests, i.e. again without modal commitments.