Modellexistenz

Modellexistenz is a term used in German-language discussions of scientific modeling to describe the status of models in relation to reality. The word blends Modell (model) and Existenz (existence) and denotes a pragmatic notion of existence: a model exists for a given purpose if it reliably represents, predicts, or explains aspects of a system within defined limits, even if the modeled system itself remains inaccessible or only partially known. This concept foregrounds usefulness and validation over ontological commitment to the modeled entity.

The idea of Modellexistenz emphasizes conditional and functional existence. Models are said to have existence in use, through validation, interoperability, and predictive success, rather than through claiming that the modeled system literally exists in the same sense as physical reality. It is contrasted with strict ontological realism, while sharing affinities with instrumentalism and representational realism.

In practice, Modellexistenz is discussed in fields such as engineering, systems science, and data science, where models guide decision making, simulations, and the operation of digital twins. It relates to broader debates about model validation, uncertainty, and the reliability of computational representations, especially under changing conditions and incomplete information.

Critics argue that invoking existence can blur the line between useful representation and ontological commitment, potentially reifying abstractions. Proponents respond that the concept clarifies when a model should be treated as legitimately usable versus when it remains a provisional or decorative artifact. Related topics include model theory, scientific modeling, digital twin, and instrumentalism.