 The perfect rationality of homo economicus imagines a hypothetical agent who has complete information about the options available for choice, perfect foresight of the consequences from choosing those options, and the wherewithal to solve an optimization problem (typically of considerable complexity) that identifies an option which maximizes the agent’s personal utility. The meaning of ‘economic man’ has evolved from John Stuart Mill’s description of a hypothetical, self-interested individual who seeks to maximize his personal utility (1844); to Jevon’s mathematization of marginal utility to model an economic consumer (1871); to Frank Knight’s portrayal of the slot-machine man of neo-classical economics (1921), which is Jevon’s calculator man augmented with perfect foresight and determinately specified risk; to the modern conception of an economically rational economic agent conceived in terms of Paul Samuelson’s revealed preference formulation of utility (1947) which, together with von Neumann and Morgenstern’s axiomatization (1944), changed the focus of economic modeling from reasoning behavior to choice behavior.