The Literalist Fallacy and the Free Energy Principle: Model Building, Scientific Realism, and Instrumentalism

Disagreement about how best to think of the relation between theories and the realities they represent has a long-standing and venerable history. We take up this debate in relation to active inference models based on the free energy principle (FEP)—a contemporary framework in computational neuroscience, theoretical biology, and the philosophy of cognitive science. Active inference under the FEP is a very ambitious form of model-based science, being applied to explain everything from neurobiological structure and function to the biology of self-organization. In this context, some find apparent discrepancies between the map (active inference models based on the FEP) and the territory (target systems) to be a compelling reason to defend instrumentalism about such models. We take this to be misguided. We identify an important fallacy made by those defending instrumentalism about active inference models. We call it the literalist fallacy: this is the fallacy of accepting or affirming instrumentalism based on the claim that the properties of active inference models based on the FEP do not literally map onto real-world target systems. We conclude that a version of scientific realism about active inference models under the FEP is a live and tenable option.