Stances and levels in the explanation of functional neurological disorder.

INTRODUCTION: Psychiatric phenomena are emergent properties of complex, distributed neurobiological systems. They are candidates for interlevel reduction between psychiatric and neurobiological levels of explanation. At the same time, they can initially be characterised in terms of what Daniel Dennett called the Intentional stance. METHODS: We review arguments drawn from the philosophy of science about the nature and explanation of emergent systemic phenomena and show how they apply to the explanation of psychiatric disorder. Examples from placebo effects, dopamine function and chronic pain illustrate how higher-level psychological explanations and lower-level neurobiological accounts interact within network-based, non-modular systems. The debate about the explanatory priority of neurobiological and psychogenic explanations of functional neurological disorder provides a case study of these ideas. RESULTS: We show how the concept of a posteriori interlevel reduction is consistent with treating psychogenic explanation as a version of the Intentional Stance approach advocated by Daniel Dennett. The Intentional Stance is consistent with an integrative multilevel explanation of psychiatric phenomena rather than an interpretative heuristic autonomous from lower levels of explanation. CONCLUSION: Clinicians should adopt a stance of pluralism: using the intentional stance as an initial, indispensable framework while remaining agnostic about explanatory priority until integrative, multilevel models are empirically validated. Functional Neurological Disorder, like chronic pain, thus requires coordinated explanation across interacting systemic levels.