Ruthless Reductionism

ABSTRACT: This chapter argues that appeals to actual scientific practice show that higher-level psychological explanations are not precluded by reductive explanation, much less rendered extinct. To exemplify this conclusion, the case of mesocorticolimbic dopamine is discussed at length.

ABSTRACT: Courtesy of its free energy formulation, the hierarchical predictive processing theory of the brain is often claimed to be a grand unifying theory. To test this claim, we consider a central case: reward-related activity of mesocorticolimbic dopaminergic (DA) systems. After reviewing the three most prominent hypotheses of DA activity—the anhedonia, incentive salience, and reward prediction error hypotheses—we conclude that current evidence vindicates explanatory pluralism, while leaves unwarranted the grand unifying claims of the predictive processing theory of the brain. More generally, we suggest that scientific progress in the cognitive sciences is unlikely to come in the form of a single overarching grand unifying theory.