Neuroeconomics is an interdisciplinary approach that combines cognitive psychology, economics, and neurobiology in studying how people make decisions. A peculiar feature of this approach is the use of neuroscientific methods for individuating the neural correlates of the cognitive processes involved in decision-making. The rationale motivating this use is that neurobiology can provide physical evidence for theoretical and abstract constructs that define the cognitive processes responsible for the human deliberative capacity. In this contribution, I’ll provide a critical account of the above assumption. I’ll argue that, in order to consider neurobiological data as reliable empirical evidence for decision-making theories, neuroeconomists need to adopt a very strong assumption about the relation of brain activity to mental states: mind–body identity theory. Without such an assumption, we should consider these data only in terms of correlation and thus too loose to be truly informative.