Delusion and Inference

Delusions are commonly defined as beliefs based on incorrect inference. But the term ‘inference’ is used in different fields with a lot of variation, which has generated confusion and merely verbal disputes about the nature and scope of delusions. In this chapter, we put forward a minimalist definition of inference. While our definition is not committed to the requirements that all inferences must involve propositional content, conscious deliberation and purely epistemic standards of rational appraisal, it can still fit clear examples of delusion in human patients. It can also productively be used for scouting intriguing theoretical and empirical implications of thinking of delusion as inferentially based in a cross-disciplinary context and in many kinds of systems, from basal organisms and soft robots all the way to collective agents. In light of empirical findings emerging within the basal cognition framework prompting a move away from neuro- and homo-centric conceptions of mental function as well as illness, it may then be more productive to adopt minimalist, (evolutionarily) gradualist notions for theorising, studying and explaining complex phenomena such as delusion across many different fields of inquiry.