Logic/Paradox in Social Choice

Much of politics is about combining individual preferences into collective choices. Collective choice problems are faced by society as a whole and by the smallest group: bargaining within and between the branches of government, campus elections, allocation of relief funds among victims of natural disasters, scoring of Olympic events, even sharing common space in a dorm room. How can preferences be combined? Our primary theoretical approach is called social choice theory, which studies how we aggregate what individuals want into what the collective “wants.” We will also touch on game theory, studying how we aggregate what individuals want and do into what the group gets, given that social outcomes usually depend on the interaction of individual choices. Our themes include the rationality of individual and group preferences, the underpinnings and implications of using majority rule, tradeoffs between aggregation methods, the fairness of group choice, the effects of institutional constraints on choice (e.g., agenda control), and the implications for democratic choice. The aggregation of preferences or choices is usually governed by some set of institutional rules, formal or informal, and we will examine some of their effects. While what we learn will be useful for thinking about many real-world problems and institutions, this class is not concerned with actual institutions in full descriptive detail, but rather with abstractable features common to collective decision making and on the abstract logic of collective choice... and the paradoxes that arise. Students will learn how to formalize varying notions of fairness, equality, and rationality. Students will learn about tradeoffs between them—what is possible and what is not? Students will learn how different voting methods work. Students will learn how strategic anticipation helps or hurts in social choice