Limits on Power and Rationality

This paper re-examines the classic impossibility results of Arrow (J Polit Econ 58(4):328–346, 1950) and Sen (J Polit Econ 78:152–157, 1970) with preferences replaced by choice functions that satisfy Weak WARP. In particular, both social and individual choices can be as in bounded rationality models of categorization, inattention or psychological constraints. A simple delegation rule that assigns a social decider to each choice satisfies Arrow’s desiderata. In addition, and in direct contrast with central ideas in economics, social choices can be ordered when all individual choice functions are anomalous. Finally, no delegation rule can be liberal [in a formal sense akin to the definition in Sen 1970], satisfy independence of irrelevant alternatives and map Weak WARP individual choice functions into Weak WARP social choice functions.