From the time of its birth, the theory of collective choice and social welfare has led a curious life. Active investigations have come from quite variegated research fields, including economics, political science, moral philosophy, and decision theory, giving depth and breadth to this rapidly developing field. Nevertheless, there are still some who would deny its legitimacy as a branch of the social sciences in general and as a branch of economics in particular. Even the message of a central result thereof, that is, Arrow's celebrated general impossibility theorem, has not been made crystal clear. Indeed, Professor Arrow wrote in his Nobel Prize lecture delivered in 1972 that “[the] philosophical and distributive implications of the paradox of social choice are still not clear. Certainly, there is no simple way out. I hope that others will take this paradox as a challenge rather than as a discouraging barrier.” This book, which is an outgrowth of my doctoral dissertation submitted to Hitotsubashi University in 1979, represents a modest attempt to respond to this challenge.

There are four main topics that I discuss in this work. First, I examine the concept of a choice function and the rationalizability thereof in terms of the revealed preference and related axioms. Second, I examine the robustness of the Arrovian impossibility theorems with special emphasis on the choice-functional formulation of social choice theory. Third, I explore the extended sympathy approach in social choice theory, thereby clarifying such concepts as envy and impartiality in this extended conceptual framework.