Why rationality is not a consequence of Hume's theory of choice

This paper argues that the theory of action proposed by Hume in the Treatise does not imply that individuals are rational in the sense of modern choice theory. An individual's behaviour is non-rational if his/her choices systematically contravene the consistency axioms of the theory, and if the causal explanation of those choices cannot credibly be offered as a reason for making them. Hume proposes a theory of causal relationships between mental states, based on associations of ideas. The relationships he postulates are liable to induce various forms of non-rational behaviour, some of which have since been observed in controlled experiments.