Separates the purely combinatorial component of Arrow's impossibility theorem in the theory of collective preference from its decision-theoretic part, and likewise for the closely related Blair/Bordes/Kelly/Suzumura theorem. Such a separation provides a particularly elegant proof of Arrow's result, via a new 'splitting theorem'.

We investigate in intuitionistic first-order logic various principles of preference relations alternative to the standard ones based on the transitivity and completeness of weak preference. In particular, we suggest two ways in which completeness can be formulated while remaining faithful to the spirit of constructive reasoning, and we prove that the cotransitivity of the strict preference relation is a valid intuitionistic alternative to the transitivity of weak preference. Along the way, we also show that the acyclicity axiom is not finitely (...) axiomatizable in first-order logic. (shrink)

A computer simulation is used to study collective judgements that an expert panel reaches on the basis of qualitative probability judgements contributed by individual members. The simulated panel displays a strong and robust crowd wisdom effect. The panel's performance is better when members contribute precise probability estimates instead of qualitative judgements, but not by much. Surprisingly, it doesn't always hurt for panel members to interpret the probability expressions differently. Indeed, coordinating their understandings can be much worse.

This is the introduction of the special issue,.

Suppose the members of a group (e.g., committee, jury, expert panel) each form a judgment on which worlds in a given set are possible, subject to the constraint that at least one world is possible but not all are. The group seeks to aggregate these individual judgments into a collective judgment, subject to the same constraint. I show that no judgment aggregation rule can solve this problem in accordance with three conditions: “unanimity,” “independence” and “non-dictatorship,” Although the result is a (...) variant of an existing theorem on “group identification” (Kasher and Rubinstein, Logique et Analyse 160:385–395, 1997), the aggregation of judgments on which worlds are possible (or permissible, desirable, etc.) appears not to have been studied yet. The result challenges us to take a stance on which of its conditions to relax. (shrink)

This paper provides an introductory review of the theory of judgment aggregation. It introduces the paradoxes of majority voting that originally motivated the field, explains several key results on the impossibility of propositionwise judgment aggregation, presents a pedagogical proof of one of those results, discusses escape routes from the impossibility and relates judgment aggregation to some other salient aggregation problems, such as preference aggregation, abstract aggregation and probability aggregation. The present illustrative rather than exhaustive review is intended to give readers (...) new to the field of judgment aggregation a sense of this rapidly growing research area. (shrink)

This paper offers a comparison of three different kinds of collective attitudes: aggregate, common, and corporate attitudes. They differ not only in their relationship to individual attitudes—e.g., whether they are “reducible” to individual attitudes—but also in the roles they play in relation to the collectives to which they are ascribed. The failure to distinguish them can lead to confusion, in informal talk as well as in the social sciences. So, the paper’s message is an appeal for disambiguation.

Political theorists have offered many accounts of collective decision-making under pluralism. I discuss a key dimension on which such accounts differ: the importance assigned not only to the choices made but also to the reasons underlying those choices. On that dimension, different accounts lie in between two extremes. The ‘minimal liberal account’ holds that collective decisions should be made only on practical actions or policies and that underlying reasons should be kept private. The ‘comprehensive deliberative account’ stresses the importance of (...) giving reasons for collective decisions, where such reasons should also be collectively decided. I compare these two accounts on the basis of a formal model developed in the growing literature on the ‘discursive dilemma’ and ‘judgment aggregation’ and address several questions: What is the trade-off between the (minimal liberal) demand for reaching agreement on outcomes and the (comprehensive deliberative) demand for reason-giving? How large should the ‘sphere of public reason’ be? When do the decision procedures suggested by the two accounts agree and when not? How good are these procedures at truthtracking on factual matters? What strategic incentives do they generate for decision-makers? My discussion identifies what is at stake in the choice between minimal liberal and comprehensive deliberative accounts of collective decisionmaking, and sheds light not only on these two ideal-typical accounts themselves, but also on many characteristics that intermediate accounts share with them. (shrink)

While a large social-choice-theoretic literature discusses the aggregation of individual judgments into collective ones, there is much less formal work on the transformation of judgments in group communication. I develop a model of judgment transformation and prove a baseline impossibility theorem: Any judgment transformation function satisfying some initially plausible conditions is the identity function, under which no opinion change occurs. I identify escape routes from this impossibility and argue that the kind of group communication envisaged by deliberative democats must be (...) "holistic": It must focus on webs of connected propositions, not on one proposition at a time, which echoes the Duhem-Quine "holism thesis" on scientific theory testing. My approach provides a map of the logical space in which different possible group communication processes are located. (shrink)

This introduces the symposium on judgment aggregation. The theory of judgment aggregation asks how several individuals' judgments on some logically connected propositions can be aggregated into consistent collective judgments. The aim of this introduction is to show how ideas from the familiar theory of preference aggregation can be extended to this more general case. We first translate a proof of Arrow's impossibility theorem into the new setting, so as to motivate some of the central concepts and conditions leading to analogous (...) impossibilities, as discussed in the symposium. We then consider each of four possible escape-routes explored in the symposium. (shrink)

This paper generalises the classical Condorcet jury theorem from majority voting over two options to plurality voting over multiple options. The paper further discusses the debate between epistemic and procedural democracy and situates its formal results in that debate. The paper finally compares a number of different social choice procedures for many-option choices in terms of their epistemic merits. An appendix explores the implications of some of the present mathematical results for the question of how probable majority cycles (as in (...) Condorcet's paradox) are in large electorates. (shrink)

The ``doctrinal paradox'' or ``discursive dilemma'' shows that propositionwise majority voting over the judgments held by multiple individuals on some interconnected propositions can lead to inconsistent collective judgments on these propositions. List and Pettit (2002) have proved that this paradox illustrates a more general impossibility theorem showing that there exists no aggregation procedure that generally produces consistent collective judgments and satisfies certain minimal conditions. Although the paradox and the theorem concern the aggregation of judgments rather than preferences, they invite comparison (...) with two established results on the aggregation of preferences: the Condorcet paradox and Arrow's impossibility theorem. We may ask whether the new impossibility theorem is a special case of Arrow's theorem, or whether there are interesting disanalogies between the two results. In this paper, we compare the two theorems, and show that they are not straightforward corollaries of each other. We further suggest that, while the framework of preference aggregation can be mapped into the framework of judgment aggregation, there exists no obvious reverse mapping. Finally, we address one particular minimal condition that is used in both theorems – an independence condition – and suggest that this condition points towards a unifying property underlying both impossibility results. (shrink)

Suppose that the members of a group each hold a rational set of judgments on some interconnected questions, and imagine that the group itself has to form a collective, rational set of judgments on those questions. How should it go about dealing with this task? We argue that the question raised is subject to a difficulty that has recently been noticed in discussion of the doctrinal paradox in jurisprudence. And we show that there is a general impossibility theorem that that (...) difficulty illustrates. Our paper describes this impossibility result and provides an exploration of its significance. The result naturally invites comparison with Kenneth Arrow's famous theorem (Arrow, 1963 and 1984; Sen, 1970) and we elaborate that comparison in a companion paper (List and Pettit, 2002). The paper is in four sections. The first section documents the need for various groups to aggregate its members' judgments; the second presents the discursive paradox; the third gives an informal statement of the more general impossibility result; the formal proof is presented in an appendix. The fourth section, finally, discusses some escape routes from that impossibility. (shrink)

On the orthodox view in economics, interpersonal comparisons of utility are not empirically meaningful, and "hence" impossible. To reassess this view, this paper draws on the parallels between the problem of interpersonal comparisons of utility and the problem of translation of linguistic meaning, as explored by Quine. I discuss several cases of what the empirical evidence for interpersonal comparisonsof utility might be and show that, even on the strongest of these, interpersonal comparisons are empirically underdetermined and, if we also deny (...) any appropriate truth of the matter, indeterminate. However, the underdetermination can be broken non-arbitrarily (though not purely empirically) if (i) we assign normative significance to certain states of affairs or (ii) we posit a fixed connection between certain empirically observable proxies and utility. I conclude that, even if interpersonal comparisons are not empirically meaningful, they are not in principle impossible. (shrink)

Why are political decisions often unfortunate? In replying to this question public‐choice theorists fail to distinguish individual conditions from systemic ones. Instead, they make sweeping claims about the egoism of man and the failure of politics. But the real problem is that we often experience government failures despite the best, the most benign motives on the part of, citizens, politicians, and bureaucrats. Better than the theory of man's innate self‐interest is the theory of the unintended consequences arising from the inherent (...) shortcomings of the political system. To wish well but to do evil—that is the dilemma of politics. (shrink)

This paper studies the welfare consequences of strategic voting in two commonly used parliamentary agendas by comparing the average utilities obtained in simulated voting under two behavioural assumptions: expected utility maximising behaviour and sincere behaviour. The average utility obtained in simulations is higher with expected utility maximising behaviour than with sincere voting behaviour under a broad range of assumptions. Strategic voting increases welfare particularly if the distribution of preference intensities correlates with voter types.

It is argued in this paper that amalgamating confirmation from various sources is relevantly different from social-choice contexts, and that proving an impossibility theorem for aggregating confirmation measures directs attention to irrelevant issues.

In the course of legal reasoning—whether for purposes of deciding an issue, justifying a decision, predicting how an issue will be decided, or arguing for how it should be decided—one often is required to reach conclusions based on a balance of reasons that is not straightforwardly reducible to the application of rules. Recent AI and Law work has modeled reason-balancing, both within and across cases, with set-theoretic and rule- or value-ordering approaches. This article explores a way to model balancing in (...) quantitative terms that may yield new questions, insights, and tools. (shrink)

This paper is a first attempt to study the problem of aggregation of individual ordinal probabilistic beliefs in an Arrowian framework. We exhibit some properties an aggregation rule must fulfil; in particular we prove the existence of a “quasi-dictator”.

We argue that a semantics for counterfactual conditionals in terms of comparative overall similarity faces a formal limitation due to Arrow’s impossibility theorem from social choice theory. According to Lewis’s account, the truth-conditions for counterfactual conditionals are given in terms of the comparative overall similarity between possible worlds, which is in turn determined by various aspects of similarity between possible worlds. We argue that a function from aspects of similarity to overall similarity should satisfy certain plausible constraints while Arrow’s impossibility (...) theorem rules out that such a function satisfies all the constraints simultaneously. We argue that a way out of this impasse is to represent aspectual similarity in terms of ranking functions instead of representing it in a purely ordinal fashion. Further, we argue against the claim that the determination of overall similarity by aspects of similarity faces a difficulty in addition to the Arrovian limitation, namely the incommensurability of different aspects of similarity. The phenomena that have been cited as evidence for such incommensurability are best explained by ordinary vagueness. (shrink)

Much of John Rawls' later work is concerned with the appli cation of his philosophical conceptions to the reality of liberal-democratic polities. I suggest that given the modern democratic reality of ethno national pluralism, Rawls' political conception of justice is insufficient to ensure democratic stability. Democratic states manage to contain ethnic pluralism while remaining compatible with liberal principles by promoting a corporate national identity. The key, I argue, lies in the particular member ship criteria devised and implemented by the state. (...) Hence, the promotion of a corporate national identity negates state neutrality, but not necessarily political liberalism. Key Words: Israel • Israeli Arabs • national identity • pluralism • Rawls. (shrink)

Numerous countries are heading toward digital infrastructures. In particular this new technology promises to help support methods for elections. However, one should be careful that such an infrastructure does not hinder the voting and representation issues. On the contrary, it should support those issues and help citizens have a clearer picture of the underlying mechanisms. This paper deals with the limits of voting procedures as they are described in classical collective choice theory and reflects on ways to aggregate electronic votes (...) stemming from various individuals that would be at the same time democratic, decisive and rational which is not feasible when candidate rankings alone are taken into account. This paper shows how electronic voting procedures could improve the situation by introducing preference-based votes. (shrink)

Belief merging aims at combining several pieces of information coming from different sources. In this paper we review the works on belief merging of propositional bases. We discuss the relationship between merging, revision, update and confluence, and some links between belief merging and social choice theory. Finally we mention the main generalizations of these works in other logical frameworks.

Though corporate social responsibility (CSR) is on the agenda of most major corporations, corporate executives still largely support the view that corporations should maximize the returns to their owners. There are two lines of defence for this position. One is the Friedmanian view that maximizing owner returns is the social responsibility of corporations. The other is a position voiced by many executives, that CSR and profits go together. This article argues that the first position is ethically untenable, while the latter (...) is not supported by empirical evidence. The implication is that there may be good reason for firms to deviate from a maxim of profit maximization. (shrink)

This paper develops an account of what it is that rational agents choose and what it is that rational agents prefer. There are three desiderata to satisfy when offering such an account. First, the account should maintain canonical axioms of rational choice theory as intuitively plausible. Here I focus on contraction and expansion consistency properties. Second, the account should prevent canonical axioms of rational choice theory from becoming trivial—it should be possible to actually violate these axioms, less rational choice theory (...) becomes useless for many purposes. Third, the account should allow rational choice theory to be put to several different philosophical projects. I show that existing accounts of what we choose and prefer fail along at least one of these metrics. The account I develop does not fail across any of these metrics. (shrink)

This article explores public reason liberalism’s indeterminacy problem, a problem that obtains when we admit significant diversity into our justificatory model. The article argues first that Gerald Gaus’s solution to the indeterminacy problem is unsatisfactory and second that, contra Gaus’s concerns, social choice theory is able to solve public reason’s indeterminacy problem. Moreover, social choice theory can do so in a way that avoids the worries raised against Gaus’s solution to the indeterminacy problem as well as the worries Gaus himself (...) raises against the use of social choice mechanisms. Social choice theory thus rescues public reason liberalism by aggregating out of indeterminacy. (shrink)

Liberty is viewed as the reigning paradigm of our age, but it is a paradigm in crisis. It is conventionally divided into two types, positive and negative. The argument here is that both types can be seen to presuppose some capacity, which may extend to power. Liberty, however, is normally accorded a higher moral value than power. But if liberty is taken itself to reflect a commitment to power, then the disvalue ostensibly placed upon the latter is unreliable. Furthermore, if (...) liberty in effect reflects a (veiled) celebration of power, then it may not be in order to accord it the precedence which is customary. We may well be entitled to look beyond liberty to other values, such as tolerance and friendship, which are not necessarily expressions of liberty, but which may prove quite as worthy. (shrink)

The paper deals briefly with several definitional issues; discusses the concept of image as it determines the way managers see the world; as one aspect of the image, examines the contrasting views of conflict and cooperation in social and organizational relationships; and then presents a typology of corporate responses to pressures for socially responsible behavior: authoritarian, manipulative and bargaining. This typology was developed on the basis of the analysis of a large number of case histories of environmental conflicts, a number (...) of which are included for purposes of illustration. Several historical examples are cited. The inference drawn from this study is that decisions become more responsible as decision-makers come under the scrutiny of and pressure from those affected by the decisions. (shrink)

Neo-Darwinism is based on the same principles as the Walrasian analysis of equilibrium. This may be surprising for evolutionary economists who resort to neo-Darwinism as a result of their dissatisfaction with Walrasian economics. As it is well-known, the principle of rationality does not play a role in neo-Darwinism. In fact, the whole (neo-)Darwinian agenda became popular exactly because it expunged the idea of rationality from nature, and hence, from equilibrium. It is less known, however, that the rationality principle is also (...) not central in Walrasian equilibrium analysis. Therefore, if we find that the rationality principle must be central to the analysis of decision making of human and nonhuman organisms, we must advance organomics . Organomics is bioeconomics understood as the use of rational choice to the study of the behavior of human and nonhuman organisms. Organomics offers a different starting point than the one offered by neo-Darwinism. (shrink)

It is commonplace to suppose that the theory of individual rational choice is considerably less problematic than the theory of collective rational choice. In particular, it is often assumed by philosophers, economists, and other social scientists that an individual's choices among outcomes accurately reflect that individual's underlying preferences or values. Further, it is now well known that if an individual's choices among outcomes satisfy certain plausible axioms of rationality or consistency, that individual's choice-behavior can be interpreted as maximizing expected utility (...) on a utility scale that is unique up to a linear transformation. Hence, there is, in principle, an empirically respectable method of measuring individuals' values and a single unified schema for explaining their actions as value maximizing. (shrink)

La théorie du choix social qui s'est développée durant les dernières décennies, notamment dans la ligne des travaux d'Arrow et de Sen , ne s'est pas seulement soldée par une série de résultats négatifs exprimés dans les théorèmes d'impossibilité d'Arrow, de Sen et d'autres; ses notions centrales ont aussi été utilisées de manière fort variée au point que cette théorie souffre aujourd'hui d'un déficit important qui se traduit par de multiples indéterminations conceptuelles.

Einstein’s razor, a corollary of Ockham’s razor, is often paraphrased as follows: make everything as simple as possible, but not simpler. This rule of thumb describes the challenge that designers of a legal system face—to craft simple laws that produce desired ends, but not to pursue simplicity so far as to undermine those ends. Complexity, simplicity’s inverse, taxes cognition and increases the likelihood of suboptimal decisions. In addition, unnecessary legal complexity can drive a misallocation of human capital toward comprehending and (...) complying with legal rules and away from other productive ends. While many scholars have offered descriptive accounts or theoretical models of legal complexity, most empirical research to date has been limited to simple measures of size, such as the number of pages in a bill. No extant research rigorously applies a meaningful model to real data. As a consequence, we have no reliable means to determine whether a new bill, regulation, order, or precedent substantially effects legal complexity. In this paper, we begin to address this need by developing a proposed empirical framework for measuring relative legal complexity. This framework is based on “knowledge acquisition”, an approach at the intersection of psychology and computer science, which can take into account the structure, language, and interdependence of law. We then demonstrate the descriptive value of this framework by applying it to the U.S. Code’s Titles, scoring and ranking them by their relative complexity. We measure various features of a title including its structural size, the net flow of its intra-title citations and its linguistic entropy. Our framework is flexible, intuitive, and transparent, and we offer this approach as a first step in developing a practical methodology for assessing legal complexity. (shrink)

The rational choice paradigm has proved to be a fruitful means of analysis and explanation in various disciplines concerned with questions of practical rationality, but in various attempts to extend its fields of application the deficiencies of the original account of rational choice have become evident. This paper tries to give a systematic overview of ways in which the rational choice paradigm can be extended and modified.

John Stuart Mill provides a classic defense of individual and group rights to liberty with respect to purely private or self-regarding matters: The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself … directly, and in the first instance, … his independence is, of right, absolute.… From this liberty of each individual, follows the liberty, within the same limits, of combination among individuals; (...) freedom to unite, for any purpose not involving harm to others: the persons combining being supposed to be of full age, and not forced or deceived. (shrink)

Ethics, Policy & Environment, Volume 14, Issue 3, Page 313-327, October 2011.