Reason as a Post-Hoc Construct: A Neurophilosophical Analysis of Rationality Without a Central Faculty

This paper develops a neurophilosophical account of rationality by arguing that what is commonly referred to as “reason” does not correspond to a unified or central faculty in the brain. Drawing on contemporary neuroscience, including predictive processing frameworks, distributed models of valuation, and prefrontal control systems, the paper shows that cognition emerges from the dynamic interaction of multiple subsystems rather than from a single rational authority. Within this framework, rationality is not treated as an intrinsic property of decision-making processes, but as a post-hoc attribution imposed through linguistic, social, and evaluative practices. What appears as coherent reasoning is reconstructed after the fact, based on narrative alignment, contextual expectations, and culturally embedded standards. This reconceptualization has direct implications for longstanding debates in philosophy of mind, cognitive science, and neuroethics. In particular, it challenges the assumption that agency depends on a centralized rational capacity and instead proposes a graded model of regulation, where responsibility is grounded in varying levels of neural and contextual constraint. The paper situates rationality within a broader system of distributed control and interpretive reconstruction, offering a shift away from faculty-based models toward process-based accounts of cognition.