In this paper, I argue for a new normative theory of rational choice under risk, namely expected comparative utility (ECU) theory. I first show that for any choice option, a, and for any state of the world, G, the measure of the choiceworthiness of a in G is the comparative utility (CU) of a in G—that is, the difference in utility, in G, between a and whichever alternative to a carries the greatest utility in G. On the basis of this (...) principle, I then argue that for any agent, S, faced with any decision under risk, S should rank his or her decision options (in terms of how choiceworthy they are) according to their comparative expected comparative utility (CECU) and should choose whichever option carries the greatest CECU. For any option, a, a's CECU is the difference between its ECU and that of whichever alternative to a carries the greatest ECU, where a's ECU is a probability-weighted sum of a's CUs across the various possible states of the world. I lastly demonstrate that in some ordinary decisions under risk, ECU theory delivers different verdicts from those of standard decision theory. (shrink)

This paper will be concerned with hard choices—that is, choice situations where an agent cannot make a rationally justified choice. Specifically, this paper asks: if an agent cannot optimize in a given situation, are they facing a hard choice? A pair of claims are defended in light of this question. First, situations where an agent cannot optimize because of incompleteness of the binary preference or value relation constitute a hard choice. Second, situations where agents cannot optimize because the binary preference (...) or value relation violates acyclicity do not constitute a hard choice. (shrink)

This paper will be concerned with hard choices—that is, choice situations where an agent cannot make a rationally justified choice. Specifically, this paper asks: if an agent cannot optimize in a given situation, are they facing a hard choice? A pair of claims are defended in light of this question. First, situations where an agent cannot optimize because of incompleteness of the binary preference or value relation constitute a hard choice. Second, situations where agents cannot optimize because the binary preference (...) or value relation violates acyclicity do not constitute a hard choice. (shrink)

Contemporary epistemological and cognitive studies, as well as recent trends in computer science and game theory have revealed an increasingly important and intimate relationship between Information, Interaction, and Agency. Agents perform actions based on the available information and in the presence of other interacting agents. From this perspective Information, Interaction, and Agency neatly ties together classical themes like rationality, decision-making and belief revision with games, strategies and learning in a multi-agent setting. Unified by the central notions Information, Interaction, and Agency, (...) the essays in this volume provide refreshing methodological perspectives on belief revision, dynamic epistemic logic, von Neumann games, and evolutionary game theory; all of which in turn are central approaches to understanding our own rationality and that of other agents. (shrink)

The books’ goal is to answer the question: Do the weaknesses of value-free economics imply the need for a paradigm shift? The author synthesizes criticisms from different perspectives (descriptive and methodological). Special attention is paid to choices over time, because in this area value-free economics has the most problems. In that context, the enriched concept of multiple self is proposed and investigated. However, it is not enough to present the criticisms towards value-free economics. For scientists, a bad paradigm is better (...) than no paradigm. Therefore, the author considers whether value-based economics with normative approaches such as economics of happiness, capability approach, libertarian paternalism, and the concept of multiple self can be the alternative paradigm for value-free economics. This book is essential reading to everyone interested in the current state of economics as a discipline. (shrink)

This article proposes a new theory of rational decision, distinct from both causal decision theory (CDT) and evidential decision theory (EDT). First, some intuitive counterexamples to CDT and EDT are presented. Then the motivation for the new theory is given: the correct theory of rational decision will resemble CDT in that it will not be sensitive to any comparisons of absolute levels of value across different states of nature, but only to comparisons of the differences in value between the available (...) options within states of nature; however, the correct theory will also resemble EDT in that it will rely on conditional probabilities (not unconditional probabilities). The new theory gives a prominent role to the notion of a “benchmark” for each state of nature, by comparison with which the value of the available options in that state of nature are measured, and so it has been called the Benchmark Theory (BT). It is argued that BT gives the right verdict on the cases that seem to be counterexamples to CDT and EDT. Finally, some objections to BT are considered and answered. (shrink)

Institutional economics and discourse theory stand unconnected next to each other, in spite of the fact that they both ask for the legitimacy of institutions (normative) and the functioning and effectiveness of institutions (positive). Both use as theoretical constructions rational individuals and the concept of consensus for legitimacy. Whereas discourse theory emphasizes the conditions of a legitimate consensus and could thus enable institutional economics to escape the infinite regress of judging a consensus legitimate, institutional economics has a tested social science (...) paradigm (rational choice) of explaining and predicting the functioning of institutions. The article outlines a theoretical synthesis of the two theories by finding points in common and possibilities of fruitful combinations concerning the problem of legitimacy, institutional design and effectiveness of legal norms. Key Words: consensus • discourse theory • effectiveness of legal rules • institutional design • legitimacy • new institutional economics. (shrink)

We here address the question of how, for a theory of justice, a concern for the promotion of equality can be combined with a concern for making people as well off as possible. Leximin, which requires making the worst off position as well off as possible, is one way of combining a concern for making people’s lives go well with a special concern for those who are especially poorly off. Many egalitarians, however, reject its near-monomaniacal focus on the worst off (...) position (to the exclusion of other poorly off persons). In this paper, we explore the possibility of combining a weak kind of egalitarianism with a weak kind of efficiency requirement in a way that avoids leximin’s obsession with the worst off position. For example, one may consider solving all cases where efficiency is not at issue by choosing the alternative that is most equal according to the Gini-coefficient or some other well-established inequality measure. All standard inequality measures sometimes judge an alternative as more equal than another alternative even though the latter maximizes the benefits of the worst off. Thus it may seem like a promising way of avoiding the leximin approach within an egalitarian framework. Surprisingly, given certain generally accepted assumptions, this turns out to be impossible. The only possible way of combining weak egalitarianism with weak efficiency requires, we shall show, the rejection of a widely accepted—but perhaps dubious—contraction consistency condition on justice or the acceptance of some version of the leximin principle. (shrink)

How can anyone be rational in a world where knowledge is limited, time is pressing, and deep thought is often an unattainable luxury? Traditional models of unbounded rationality and optimization in cognitive science, economics, and animal behavior have tended to view decision-makers as possessing supernatural powers of reason, limitless knowledge, and endless time. But understanding decisions in the real world requires a more psychologically plausible notion of bounded rationality. In Simple heuristics that make us smart (Gigerenzer et al. 1999), we (...) explore fast and frugal heuristics – simple rules in the mind's adaptive toolbox for making decisions with realistic mental resources. These heuristics can enable both living organisms and artificial systems to make smart choices quickly and with a minimum of information by exploiting the way that information is structured in particular environments. In this précis, we show how simple building blocks that control information search, stop search, and make decisions can be put together to form classes of heuristics, including: ignorance-based and one-reason decision making for choice, elimination models for categorization, and satisficing heuristics for sequential search. These simple heuristics perform comparably to more complex algorithms, particularly when generalizing to new data – that is, simplicity leads to robustness. We present evidence regarding when people use simple heuristics and describe the challenges to be addressed by this research program. Key Words: adaptive toolbox; bounded rationality; decision making; elimination models; environment structure; heuristics; ignorance-based reasoning; limited information search; robustness; satisficing; simplicity. (shrink)

Public reason theories are characterized by three conditions: constructivism, representation, and stability. Constructivism holds that justification does not rely on any antecedent moral or political values outside of the procedure of agreement. Representation holds that the reasons for the choice in the model must be rationally explicable to real agents outside the model. Stability holds that the principles chosen in the procedure should be stable upon reflection, especially in the face of diversity in a pluralistic society. Choice procedures that involve (...) at least two-stages with different information, as Rawls’s theory does, will be path-dependent and not meet the condition of representation since it will not be globally coherent. Attempts to solve this problem without eliminating the segmentation of choice in the procedure will run afoul of constructivism or stability. This problem is instructive because it highlights how public reason theories must evolve in the face of increased concerns about diversity. (shrink)

Whereas the literature on choice overload has shown that people tend to defer their choice or experience less satisfaction under choice proliferation, this paper aims to test how the profusion of choice directly affects individuals’ revealed preferences over options. To do so, we run an experiment where subjects have to compare familiar and unfamiliar options under different choice contexts. We hypothesize that, as the choice set expands, the decisions become harder and more costly and subjects may find familiar items relatively (...) more attractive. Our results provide clear evidence of set size dependence of revealed preferences: Subjects prefer familiar items more frequently in larger choice sets. This evidence is robust to a number of experimental variations and statistical controls. (shrink)

On analyzing the problem that arises whenever the set of maximal elements is large, and a selection is then required (see Peris & Subiza 1998), we realize that logical ways of selecting among maximals violate the classical notion and axioms of rationality. We arrive at the same conclusion if we analyze solutions to the problem of choosing from a tournament (where maximal elements do not necessarily exist). So, in our opinion the notion of rationality must be discussed, not only in (...) the traditional sense of external conditions (Sen 1993), but in terms of the internal information provided by the binary relation. (shrink)

Current psychology of human reasoning is divided into several different approaches. For instance, there is a major dispute over the question whether human beings are able to apply norms of the formal models of rationality such as rules of logic, or probability and decision theory, correctly. While researchers following the “heuristics and biases” approach argue that we deviate systematically from these norms, and so are perhaps deeply irrational, defenders of the “bounded rationality” approach think not only that the evidence for (...) this conclusion is problematic but also that we should not, at least not very often, use formal norms in reasoning. I argue that while the evidence for heuristics and biases is indeed questionable, the bounded rationality approach has its limits too. Most especially, we should not infer that formal norms play no role in a comprehensive theory of rationality. Instead, formal and bounded rules of reasoning might even be connected in a more comprehensive theory of rationality. (shrink)

This paper studies a generalization of rational choice theory. I briefly review the motivations that Helzner gives for his conditional choice construction . Then, I focus on the important class of conditional choice functions with vacuous second tiers. This class is interesting for both formal and philosophical reasons. I argue that this class makes explicit one of conditional choice’s normative motivations in terms of an account of neutrality advocated within a certain tradition in decision theory. The observations recorded—several of which (...) are generalizations of central results in the standard theory of rational choice—are intended to provide further insight into how conditional choice generalizes the standard account and are offered as additional evidence of the fruitfulness of the conditional choice framework. (shrink)

(2013). Why humans are (sometimes) less rational than other animals: Cognitive complexity and the axioms of rational choice. Thinking & Reasoning: Vol. 19, No. 1, pp. 1-26. doi: 10.1080/13546783.2012.713178.

Guessing is a familiar activity, one we engage in when we are uncertain of the answer to a question under discussion. It is also an activity that lends itself to normative evaluation: some guesses are better than others. The question that interests me here is what makes for a good guess. In recent work, Dorst and Mandelkern have argued that good guesses are distinguished from bad ones by how well they optimize a tradeoff between accuracy and specificity. Here I argue (...) that Dorst and Mandelkern’s implementation of this idea fails to satisfy some plausible constraints on good guesses, and I develop an alternative implementation that satisfies the relevant constraints. The result is a new account of good guesses which retains the positive aspects of Dorst and Mandelkern’s proposal, but without the drawbacks. (shrink)

À la fin des années 1990, plusieurs tendances convergentes en économie, psychologie et neuroscience ont préparé le terrain pour la naissance d’un nouveau champ scientifique qualifié de « neuroéconomie ». Comme pour toute discipline émergente – pensons par exemple à l’économie mathématique, l’économétrie ou l’économie expérimentale en d’autres temps – la neuroéconomie est plutôt controversée en économie. Elle soulève un grand nombre de questions d’ordre empirique, méthodologique et philosophiques donnant lieu à des débats et controverses que l’article identifie et discute (...) à travers trois questions majeures relatives aux connaissances produites : Sont-elles fiables? Sont-elles scientifiquement légitimes? Sont-elles utiles pour les économistes? Sans prétendre à l’exhaustivité, ce cadre analytique permet de comprendre l’essence des principales critiques adressées à la neuroéconomie. Dans le même temps, l’article éclaire la nature des réponses susceptibles d’être apportées à ces critiques au vu des progrès conceptuels et empiriques qu’a connus ce champ de recherche depuis son émergence et à la lumière du tournant apparu dans l’agenda de la neuroéconomie au cours de la dernière décennie. JEL Codes : A12, B41, C51, C81, C9, D03, D87. (shrink)

The independence of irrelevant alternatives is a popular and important axiom of decision theory. It states, roughly, that one’s choice from a set of options should not be influenced by the addition or removal of further, unchosen options. In recent debates, a number of authors have given putative counterexamples to it, involving intuitively rational agents who violate IIA. Generally speaking, however, these counterexamples do not tend to move IIA’s proponents. Their strategy tends to be to individuate the options that the (...) agent faces differently, so that the case no longer counts as a violation of IIA. In this paper, we examine whether this strategy succeeds. We argue that the ways of individuating options required to save IIA from the most problematic counterexamples—in particular, cases where agents violate IIA due to nonconsequentialist moral beliefs—do so only at the expense of severely compromising its central function within decision theory. (shrink)

This paper offers a novel account of how complaints of unfairness arise in risky distributive cases. According to a recently proposed view in distributive ethics, the Competing Claims View, an individual has a claim to a benefit when her well-being is at stake, and the strength of this claim is determined by the expected gain to the individual’s well-being, along with how worse off the individual is compared to others. If an individual is at a lower level of well-being than (...) another, their claim to a given benefit is stronger. On this view, the strength of individuals’ claims are a function of their comparative well-being levels. In this paper, I instead argue that competing claims obtain only when a particular relationship obtains between the fates of individuals: that one individual’s gain is at the expense of another. This is a particular complaint that obtains when the fates of individuals are tied together in such a way that inequality that is to the detriment of the person who is worse off is guaranteed to obtain. I demonstrate that this complaint arises only when individuals are exposed to a particular type of risk that allows some to gain only if others lose. As such, I propose that complaints of unfairness occur less frequently than we might think if we take the Competing Claims View to be true. A purely comparative view is unable to account for this unique complaint of unfairness. I argue that this complaint is not only independently plausible, but can serve as a foundation for a more general account of competing claims complaints. (shrink)

In recent years there has been a growing consensus that ordinary reasoning does not conform to the laws of classical logic, but is rather nonmonotonic in the sense that conclusions previously drawn may well be removed upon acquiring further information. Even so, rational belief formation has up to now been modelled as conforming to some fundamental principles that are classically valid. The counterexample described in this paper suggests that a number of the most cherished of these principles should not be (...) regarded as valid for commonsense reasoning. An explanation of this puzzling failure is given, arguing that a problem in the theory of rational choice transfers to the realm of belief formation. (shrink)

A new Arrovian impossibility is obtained without invoking independence of irrelevant alternatives type assumptions. The new conditions leading to the impossibility are based on the concept of power of enforcement, and specify how this power can (see A3) or cannot be expanded (see A1, A2 and A4).

Suppose that each of the following four conditions obtains: 1. You can save either a greater or a lesser number of innocent people from (equally) serious harm. 2. You can do so at trivial cost to yourself. 3. If you act to save, then the harm you prevent is harm that would not have been prevented if you had done nothing. 4. All other things are equal. A skeptic about saving the greater number rejects the common-sensical claim that you have (...) a duty to save the greater number in such circumstances. (shrink)

In this article, I argue that it makes a moral difference whether an individual is worse off than she could have been. Here, I part company with consequentialists such as Parfit and side with contractualists such as Scanlon. But, unlike some contractualists, I reject the view that all that matters is whether a principle can be justified to each particular individual, where such a justification is attentive to her interests, complaints and other claims. The anonymous goodness of a distribution also (...) matters. My attempt to reconcile contractualist and consequentialist approaches proceeds via a serious of reflections on cases. (shrink)

Despite the conclusions from the contemporary philosophy of science, many economists cherish the ideal of positive science. Therefore, value-free economics is still the central paradigm in economics. The first aim of the paper is to investigate economics' axiomatic assumptions from an epistemological perspective. The critical analysis of the literature shows that the positive-normative dichotomy is exaggerated. Moreover, value-free economics is based on normative foundations that have a negative impact on individuals and society. The paper's second aim is to show that (...) economics' normativity is not a problem because the discussion concerning values is possible and unavoidable. In this context, Weber and other methodologists are investigated. The conclusion of the paper is that science can thrive without strict methodological rules thanks to institutional mechanisms. Therefore, economists could learn from artists who accept the world without absolute rules. This perspective opens the possibility for methodological pluralism and normative approaches. (shrink)

Hans Rott has argued, most recently in his book Change, Choice and Inference, that certain formal correspondences between belief revision and rational choice have important philosophical implications, claiming that the former strongly indicate the unity of practical and theoretical reason as well as the primacy of practical reason. In this paper, I confront Rott's argument with three serious challenges. My conclusion is that, while Rott's work is indisputable as a formal achievement, the philosophical consequences he wants to draw are not (...) forthcoming. (shrink)

Amartya Sen argues that it is not, after all, irrational to reverse preferences when your choices are amplified by an ‘irrelevant’ alternative. He offers examples such as the agent who always picks the next-to-largest piece of cake. Given a choice between a larger and smaller piece, I will prefer the smaller one. But when a third and largest piece in added to my alternatives, I will now prefer the formerly largest piece over the smallest piece. This violates ‘contraction consistency’: a (...) third alternative should not have made any difference in my preferences regarding the first two. Such examples are shown to rely on descriptions which omit features crucial to choice. These features, and all identifying features relevant to my decision, should be included in the descriptions of the alternatives. An adequate description does not smuggle norms into the overt act of choice, but it does include the non-normative characteristics without which my decision-rules, if any, cannot be applied. When alternatives are adequately described, Sen’s inconsistencies disappear. The result is a clearer and more resillent, but also less aggressive notion of behavioral consistency. (shrink)

La teoría “coaseana” del derecho, y el Análisis Económico del Derecho en general, asumen implícitamente la veracidad de dos premisas comportamentales: la “exogeneidad de la preferencia” y la “independencia de la referencia”. Este artículo señala algunas objeciones a estas premisas, luego evidencia algunas implicaciones acerca de: cómo el AED –desde un punto de vista positivo– pronostica los comportamientos de las personas y los efectos de las normas jurídicas entendidas como incentivos, y cómo, –desde un punto de vista normativo– la teoría (...) económica sugiere las decisiones del juez o del legislador. El artículo además presenta los desafíos a los que se enfrenta el AED al aceptarse la premisa comportamental de que las personas valoran los derechos individuales, no en términos absolutos, sino en términos relativos, comparados con un punto de referencia. (shrink)

Simon introduced satisficing, but he did not provide a precise definition or analysis. Other researchers have subsequently interpreted satisficing in various ways, but a consensus perspective still has not emerged. This paper interprets satisficing as a class of decision strategies that a person might use when seeking to optimize in a setting where deliberation is costly. Costly deliberation lies at the heart of Simon’s motivation of satisficing, but he did not formalize the idea. I do so here, studying decision making (...) as a problem of minimax-regret planning in which costly deliberation enables a person to reduce ambiguity. I report simple specific findings on how the magnitude of deliberation costs may affect choice of a decision strategy. (shrink)

In this essay, I will examine Broome’s argument in Weighing Goods (1991; sections 5.4 and 5.5) that aims to show that moderate Humeanism, according to which any coherent sets of preferences should be rationally acceptable, is not a sustainable view of decision theory. I will focus more specifically on the argument Broome uses to support his claim, and show that although it may get some traction, it does not undermine moderate Humeanism as we know it. After reconstructing Broome’s argument, I (...) argue that standard decision theory supposes that the representation of a decision problem fully captures what is relevant to the agent, and therefore has nothing to say about the legitimacy of the representation in question. I argue that although Broome’s criticism does not jeopardize moderate Humeanism, it does pave the way for a new area of research in decision theory. (shrink)

Consistency of choice is a fundamental and recurring theme in decision theory, social choice theory, behavioral economics, and psychological sciences. The purpose of this paper is to study the consistency of choice independent of the particular decision model at hand. Consistency is viewed as an inherently logical concept that is fundamentally void of connotation and is thus disentangled from traditional rationality or consistency conditions imposed on decision models. The proposed formalization of consistency takes two forms: internal consistency, which refers to (...) the property that a choice model does not generate contradictory statements; and semantic consistency, which refers to the idea that a theory’s predictions are valid with respect to some observed data. In addressing semantic consistency, the relationship between theory and data is analyzed in terms of so-called duality mappings, which allow a passage between the two universes in a way that consistency is preserved. The formalization of consistency concepts relies on adapting the revealed preference theory to the context-dependent setting. The paper concludes by discussing the implications of the proposed framework and how it relates to classical revealed preference theory and other formalizations of the relationship between the theory and reality of choice. (shrink)

The paper examines representative cases of ``dishonest'''' voting. In all but one case the claim that ``strategic voting'''' is ``dishonest'''' is refuted. In all cases the effects of ``misrepresentation'''' need never harm any majority. Indeed majorities may benefit from ``strategy'''' (in non-cycle cases too). In fact democracy demands ``strategy''''. Although the universal value of the choice set is disputed even in the one recalcitrant case, the result is, after all, an element in the ``honest'''' choice set.

We introduce a “reason-based” framework for explaining and predicting individual choices. It captures the idea that a decision-maker focuses on some but not all properties of the options and chooses an option whose motivationally salient properties he/she most prefers. Reason-based explanations allow us to distinguish between two kinds of context-dependent choice: the motivationally salient properties may (i) vary across choice contexts, and (ii) include not only “intrinsic” properties of the options, but also “context-related” properties. Our framework can accommodate boundedly rational (...) and sophisticatedly rational choice. Since properties can be recombined in new ways, it also offers resources for predicting choices in unobserved contexts. (shrink)

Behaviourism is the view that preferences, beliefs, and other mental states in social-scientific theories are nothing but constructs re-describing people's behaviour. Mentalism is the view that they capture real phenomena, on a par with the unobservables in science, such as electrons and electromagnetic fields. While behaviourism has gone out of fashion in psychology, it remains influential in economics, especially in ‘revealed preference’ theory. We defend mentalism in economics, construed as a positive science, and show that it fits best scientific practice. (...) We distinguish mentalism from, and reject, the radical neuroeconomic view that behaviour should be explained in terms of brain processes, as distinct from mental states. (shrink)

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 this article, we present a contextually embedded choice theory. Using concepts and tools of poset mathematics, we show how to include in rational choice theory cultural and social effects. Specifically, we define some choice superstructures, seen as choice set transformations imposed by cultural and social norms. As we shall argue, these transformations can be of help to explain choice behavior within different contexts. Moreover, we show that, once choice superstructures are taken into account, some well-known results about maximizing and (...) optimizing behavior are easily confirmed and some insights on intransitive choices may be phased out. (shrink)

The rationalization of context-based choice is usually based on the assumption that preferences are context-dependent. In this paper, we show that context-based choice can be due to the characteristics of the choice procedure applied by the individual and not to the dependence of preferences (stochastic or deterministic) on the context. Our arguments are illustrated focusing on the much-studied dominated-alternative effects.

This paper shows how alternative, culturally-determined motivational forces can be substituted for self-interest or rationality in the theory of choice. Several possibilities are considered, including the replacement of preference optimization by such propellants as the selection of the `second best' or the `central' option. It is argued that although all choice behavior, even that consistent with the alternatives considered, can ultimately be understood as satisfying the criterion of rationality, richer and more meaningful explanation is obtained by focusing on culturally significant (...) alternative motivations when the latter turn out, in particular environments, to be more important than self-interest. (shrink)

Natural selection is often envisaged as the ultimate cause of the apparent rationality exhibited by organisms in their specific habitat. Given the equivalence between selection and rationality as maximizing processes, one would indeed expect organisms to implement rational decision-makers. Yet, many violations of the clauses of rationality have been witnessed in various species such as starlings, hummingbirds, amoebas and honeybees. This paper attempts to interpret such discrepancies between economic rationality and biological rationality. After having distinguished two kinds of rationality we (...) introduce irrationality as a negation of economic rationality by biologically rational decision-makers. Focusing mainly on those instances of irrationalities that can be understood as exhibiting inconsistency in making choices, i.e. as non-conformity of a given behaviour to axioms such as transitivity or independence of irrelevant alternatives, we propose two possible families of Darwinian explanations that may account for these apparent irrationalities. First, we consider cases where natural selection may have been an indirect cause of irrationality. Second, we consider putative cases where violations of rationality axioms may have been directly favored by natural selection. Though the latter cases seem to clearly contradict our intuitive representation of natural selection as a process that maximizes fitness, we argue that they are actually unproblematic; for often, they can be redescribed as cases where no rationality axiom is violated, or as situations where no adaptive solution exists in the first place. (shrink)

We characterize seniority rules, also known as lexical dictatorships, under weak consistency constraints on the group’s choice function. These constraints are base triple-acyclicity in the case of binary choices and rationalizability (although not rationality) in the case of choices between an arbitrary number of alternatives. Existing results on these weakened constraints remain silent on the treatment of the group’s most junior individuals and therefore do not yield a complete characterization of seniority rules. We also impose a universal domain, binary strict (...) Pareto optimality, binary Pareto indifference, binary independence of irrelevant alternatives, and the newly introduced condition of conflict resolution. The latter condition requires a social choice rules not to remain indecisive between alternatives for which individuals have conflicting preferences. (shrink)