Ever since Sen criticized the notion of internal consistency of choice, there exists a widespread perception that the standard rationalizability approach to the theory of choice has difficulties in coping with the existence of external norms. We introduce a concept of norm-conditional rationalizability and show that external norms can be made compatible with the methods underlying the traditional rationalizability approach. To do so, we characterize norm-conditional rationalizability by means of suitable modifications of revealed preference axioms that are well established in the theory of rational choice on general domains as analysed in contributions by Richter and Hansson, for example. We compare our approach to alternative suggestions that have appeared in response to Sen's criticisms, and we discuss its links to Sen's notion of self-imposed choice constraints.

The tenuous claims of cost-benefit analysis to guide policy so as to promote welfare turn on measuring welfare by preference satisfaction and taking willingness-to-pay to indicate preferences. Yet it is obvious that people's preferences are not always self-interested and that false beliefs may lead people to prefer what is worse for them even when people are self-interested. So welfare is not preference satisfaction, and hence it appears that cost-benefit analysis and welfare economics in general rely on a mistaken theory of well-being. This essay explores the difficulties, criticizes standard defences of welfare economics, and then offers a new partial defence that maintains that welfare economics is independent of any philosophical theory of well-being. Welfare economics requires nothing more than an evidential connection between preference and welfare: in circumstances in which people are concerned with their own interests and reasonably good judges of what will serve their interests, their preferences will be reliable indicators of what is good for them.

The paradigm for modelling decision-making under uncertainty has undoubtedly been the theory of Expected Utility, which was first developed by von Neumann and Morgenstern (1944) and later extended by Savage (1954) to the case of subjective uncertainty. The inadequacy of the theory of Subjective Expected Utility (SEU) as a descriptive theory was soon pointed out in experiments, most famously by Allais (1953) and Ellsberg (1961). The observed departures from SEU noticed by Allais and Ellsberg became known as “paradoxes”. The Ellsberg paradox gave rise, several years later, to a new literature on decision-making under ambiguity. The theoretical side of this literature was pioneered by Schmeidler (1989). This literature views the departures from SEU in situations similar to those discussed by Ellsberg as rational responses to ambiguity. The rationality is “recovered” by relaxing Savage's Sure-Thing principle and adding an ambiguity-aversion postulate. Thus the ambiguity-aversion literature takes a normative point of view and does consider Ellsberg-type choices as behavioural “anomalies”.

According to Mark Rubinstein (2006) ‘In 1952, anticipating Kenneth Arrow and John Pratt by over a decade, he [de Finetti] formulated the notion of absolute risk aversion, used it in connection with risk premia for small bets, and discussed the special case of constant absolute risk aversion.’ The purpose of this note is to ascertain the extent to which this is true, and at the same time, to correct certain minor errors that appear in de Finetti's work.

We provide a critical assessment of the ambiguity aversion literature, which we characterize in terms of the view that Ellsberg choices are rational responses to ambiguity, to be explained by relaxing Savage's Sure-Thing principle and adding an ambiguity-aversion postulate. First, admitting Ellsberg choices as rational leads to behaviour, such as sensitivity to irrelevant sunk cost, or aversion to information, which most economists would consider absurd or irrational. Second, we argue that the mathematical objects referred to as “beliefs” in the ambiguity aversion literature have little to do with how an economist or game theorist understands and uses the concept. This is because of the lack of a useful notion of updating. Third, the anomaly of the Ellsberg choices can be explained simply and without tampering with the foundations of choice theory. These choices can arise when decision makers form heuristics that serve them well in real-life situations where odds are manipulable, and misapply them to experimental settings.

It is widely recognized that prioritizing health care resources by their relative cost-effectiveness can result in lower priority for the treatment of disabled persons than otherwise similar non-disabled persons. I distinguish six different ways in which this discrimination against the disabled can occur. I then spell out and evaluate the following moral objections to this discrimination, most of which capture an aspect of its unethical character: it implies that disabled persons' lives are of lesser value than those of non-disabled persons; it constitutes “double jeopardy” or violates Frances Kamm's non-linkage principle; it conflicts with equality of opportunity; it conflicts with fairness, which requires ignoring (some/most) differential impacts of treatment; it wrongly gives lower priority to disabled persons for equally effective treatment; it conflicts with giving all persons an equal chance to reach their full potential; and, it is in conflict with giving priority to the worse off.

It often appears that the most appropriate form of addressing disadvantage related to disability is through policies that can be called “status enhancements”: changes to the social, cultural and material environment so that the difficulties experienced by those with impairments are reduced, even eradicated. However, status enhancements can also have their limitations. This paper compares the relative merits of policies of status enhancement and “personal enhancement”: changes to the disabled person. It then takes up the question of how to assess the priority of the claims of disabled people in the face of scarcity of resources for which there can be many competing social claims, arguing for the theory of “declustering disadvantage”.

Paradoxical results concerning judgment aggregation have recently been invoked to defend the thesis that a corporate agent can be morally responsible for a decision without any of its individual members bearing such responsibility. I contend that the arguments offered for this irreducibility thesis are inconclusive. They do not pay enough attention to how we evaluate individual moral responsibility, in particular not to the role that a flawed assessment of the normative reasons that bear on the issue to be decided on play in this context. I go on to propose a method for distributing corporate responsibility to individual members within the judgment aggregation framework.

This note argues that, under some circumstances, it is more rational not to behave in accordance with a Bayesian prior than to do so. The starting point is that in the absence of information, choosing a prior is arbitrary. If the prior is to have meaningful implications, it is more rational to admit that one does not have sufficient information to generate a prior than to pretend that one does. This suggests a view of rationality that requires a compromise between internal coherence and justification, similarly to compromises that appear in moral dilemmas. Finally, it is argued that Savage's axioms are more compelling when applied to a naturally given state space than to an analytically constructed one; in the latter case, it may be more rational to violate the axioms than to be Bayesian.

This note comments on Bruni and Sugden's interesting notion of fraternity among contract partners as joint commitment to cooperate for mutual benefit. I raise two points on their paper, both concerning the role of sacrifice. First I maintain that, differently from other social preferences, guilt aversion (or warm glow) does not imply self-sacrifice. Secondly, I argue that aiming for mutual benefit does not prevent individuals from facing trade-offs between their own and their partners’ surplus, so the notion of sacrifice cannot be entirely eschewed. To the contrary, reciprocal ‘sacrifices’ enhance cooperative intentions and help create feelings of friendliness.

In this book, the French economist and philosopher Serge-Christophe Kolm discusses the problem of what he calls “macrojustice”, which “concerns the most general rules of society and their application to the distribution of the benefits from the main resources” (MJ 1). He reminds his readers that the first and most important challenge for any policy analysis is the spelling out of its ethical foundations. On that basis, he argues in favour of what is nothing less than a paradigm shift in the theory of optimal income taxation, rejecting the whole traditional approach in public economics as being welfarist and too strongly focused on the problem of labour market distortions. As an alternative, he proposes an approach based on the ideal of equal freedom, and works out a specific tax proposal: equal-labour income equalization (or ELIE). He claims that ELIE is a general and operational solution for the organization of the distribution branch of taxation and public expenditure policy that does not create labour market distortions.

Are foundations of models of ambiguity-sensitive preferences too flawed to be usefully applied to economic models? Al-Najjar and Weinstein (2009) say such is indeed the case. In this paper, first, we point out that many of the key arguments by Al-Najjar and Weinstein do not apply to quite a few of the ambiguity preference models of more recent vintage, and therefore to that extent do not undermine the foundational aspects or applicability of ambiguity models in general. Second, we argue the focus in that paper on Ellsberg examples is an overly narrow concern; the Ellsberg examples have their uses but they are not the best context to understand why reasonable real-world agents may find acting in an ambiguity-sensitive manner normatively or prescriptively appealing. Finally, normative considerations aside, we submit that Al-Najjar and Weinstein are unduly dismissive of the power of such preferences to provide illuminating positive analyses of economic phenomena.

Erik Schokkaert's note presents a very good summary of the theory of macrojustice and a very good list of the directions of research it points to. This is quite fitting since a research programme defines a paradigm, and he sees this proposal as a paradigm shift. This is also very appropriate since his own qualifications are the best for advancing fast in these research topics. I have only a very small number of qualifications to add to his presentation, but I prefer to begin with emphasizing the most important issues. Two aspects can be seen as the most important: the de facto axiomatic derivation of the solution ELIE and its application on the one hand, and the present state of scholarly studies of the optimum or just distribution of income on the other hand. Let us enter by the second door (as opposed to what is done in the book Macrojustice). This will lead us to conclude with a more synthetic and broader view of the basic logic of the paradigms of justice and of the surprising recent history of their interpretations.

Al-Najjar and Weinstein (2009) argue that the extant literature on ambiguity aversion is not successful in accounting for Ellsberg choices as rational responses to ambiguity. We concur, and propose that rational choice under ambiguity aims at robustness rather than avoidance of ambiguity. A central argument explains why robust choice is intrinsically context-dependent and legitimately violates standard choice consistency conditions. If choice consistency is forced, however, ambiguity-aversion emerges as a semi-rational response to ambiguity.

An article by Luigino Bruni and Robert Sugden published in this journal argues that market relations contain elements of what they call ‘fraternity’. This Response demonstrates that my own views on interpersonal relations and markets – which originated in the feminist analysis of caring labour – are far closer to Bruni and Sugden's than they acknowledge in their article, and goes on to discuss additional important dimensions of sociality that they neglect.

Al-Najjar and Weinstein (2009) propose to scrutinize the implications of recent theories of ambiguity in dynamic settings. They conclude that such implications are so unreasonable as to cast doubts on the legitimacy of the theories under consideration. The present paper argues that the seemingly unreasonable implications highlighted by Al-Najjar and Weinstein can be understood as the result of basic trade-offs that arise naturally in the presence of ambiguity. In particular, Al-Najjar and Weinstein are uncomfortable with the possibility that an ambiguity-averse individual may reject freely available information; however, this phenomenon simply reflects a trade-off between the intrinsic value of information, which is positive even in the presence of ambiguity, and the value of commitment.

This paper responds to Gui and Nelson's separate comments on our paper ‘Fraternity’, which analysed sociality in markets as joint commitment to mutual assistance. We argue that our analysis is fundamentally different both from Nelson's analysis (a mixture of self-interested and intrinsic motivations) and from that provided by theories of warm glow or guilt aversion, as discussed by Gui. We agree with Gui that, in initiating and maintaining cooperative relationships, individuals sometimes incur personal costs to benefit others without any certainty of reciprocation, but we argue that the intentions underlying such actions are cooperative rather than self-sacrificing.

The pioneering contributions of Bewley, Gilboa and Schmeidler highlighted important weaknesses in the foundations of economics and game theory. The Bayesian methodology on which these fields are based does not answer such basic questions as what makes beliefs reasonable, or how agents should form beliefs and expectations. Providing the initial impetus for debating these issues is a contribution that will have the lasting value it deserves.