Johanna Thoma

As readers of this journal can attest to, although philosophers and economists are somewhat used to talking to and learning from each other, it tends to be the subset of philosophers working in decision theory, philosophy of science, and particular areas of ethics and political philosophy that contribute to our interdisciplinary field of research. The book that is the subject of this review symposium, Anna Mahtani’s The Objects of Credence (Oxford University Press, 2024), is a wonderful exemplar of what can be learned when a different branch of philosophy is brought to bear on central questions in this field. Both philosophers and economists talk about and work with credences, or degrees of belief, all the time. These are usually modelled as probabilities, which are in turn usually thought of as attaching to propositions. But it has long been argued by philosophers of language that propositions cannot be the objects of credence. Mahtani’s book is an investigation into all that begins to unravel once we accept this insight. The results have profound implications both for rational choice modelling and for welfare economics.

A growing number of decision theorists have, in recent years, defended the view that rationality is permissive under risk: Different rational agents may be more or less risk-averse or risk-inclined. This can result in them making different choices under risk even if they value outcomes in exactly the same way. One pressing question that arises once we grant such permissiveness is what attitude to risk we should implement when choosing on behalf of other people. Are we permitted to implement any of the rationally permissible risk attitudes, is there some specific risk attitude that is required when choosing for others, or are we required to defer to the risk attitudes of the people on whose behalf we are choosing? This article elaborates on this question, explains its wider practical and theoretical significance, provides an overview of existing answers, and explores how to go about providing a more systematic account of how to choose on behalf of others in risky contexts.

Precautionary principles are frequently appealed to both in public policy and in discussions of individual decision-making. They prescribe omission or reduction of an activity, or taking precautionary measures whenever potential harmful effects of the activity surpass some threshold of likelihood and severity. One crucial appeal of precautionary principles has been that they seem to help guard against procrastinating on confronting certain kinds of risk. I raise a challenge for precautionary principles serving as effective action-guiding tools to guard against (policy) inaction, procrastination, or recklessness. Since risks that are sufficiently harmful and sufficiently likely to fulfil the antecedent of a precautionary principle typically accumulate over time, precautionary principles are only effective if they constrain an agent’s decision-making over time. On the basis of this observation, I argue for two claims. First, to yield the verdicts proponents of precautionary principles would like to make, precautionary principles must be understood to be diachronic principles, which requires some added structure to how they are commonly formulated. Second, such diachronic precautionary principles invite policy procrastination and inaction in their own right, due to both the vagueness of thresholds, and because agents will often fail to abide by the principles if they ignore bygone risks.

This article presents two related challenges to the idea that, to ensure policy evaluation is comprehensive, all costs and benefits should be aggregated into a single, equity-weighted wellbeing metric. The first is to point out how, even allowing for equity-weighting, the use of a single metric limits the extent to which we can take distributional concerns into account. The second challenge starts from the observation that in this and many other ways, aggregating diverse effects into a single metric of evaluation necessarily involves settling many moral questions that reasonable people disagree about. This raises serious questions as to what role such a method of policy evaluation can and should play in informing policy-making in liberal democracies. Ultimately, to ensure comprehensiveness of policy evaluation in a wider sense, namely, that all the diverse effects that reasonable people might think matter are kept score of, we need multiple metrics as inputs to public deliberation.

Where artificial agents are not liable to be ascribed true moral agency and responsibility in their own right, we can understand them as acting as proxies for human agents, as making decisions on their behalf. What I call the ‘Moral Proxy Problem’ arises because it is often not clear for whom a specific artificial agent is acting as a moral proxy. In particular, we need to decide whether artificial agents should be acting as proxies for low-level agents — e.g. individual users of the artificial agents — or whether they should be moral proxies for high-level agents — e.g. designers, distributors or regulators, that is, those who can potentially control the choice behaviour of many artificial agents at once. Who we think an artificial agent is a moral proxy for determines from which agential perspective the choice problems artificial agents will be faced with should be framed: should we frame them like the individual choice scenarios previously faced by individual human agents? Or should we, rather, consider the expected aggregate effects of the many choices made by all the artificial agents of a particular type all at once? This paper looks at how artificial agents should be designed to make risky choices, and argues that the question of risky choice by artificial agents shows the moral proxy problem to be both practically relevant and difficult.

This paper defends revealed preference theory against a pervasive line of criticism, according to which revealed preference methodology relies on appealing to some mental states, in particular an agent’s beliefs, rendering the project incoherent or unmotivated. I argue that all that is established by these arguments is that revealed preference theorists must accept a limited mentalism in their account of the options an agent should be modelled as choosing between. This is consistent both with an essentially behavioural interpretation of preference and with standard revealed preference methodology. And it does not undermine the core motivations of revealed preference theory.

Most philosophical decision theorists and philosophers of the social sciences believe that decision theory is and should be in the business of providing folk psychological explanations of choice behaviour, and that it can only do so if we understand the preferences, utilities and probabilities that feature in decision-theoretic models as ascriptions of mental states not reducible to choice. The behavioural interpretation of preference and related concepts, still common in economics, is consequently cast as misguided. This paper argues that even those who strive to provide folk psychological explanations should side with the economists, and adopt a behavioural interpretation of the preferences featuring in decision-theoretic models. Under a mentalistic interpretation of preference, decision-theoretic models do not straightforwardly provide ordinary folk psychological explanations. Instead, they involve controversial enough commitments about the mental causes of choice to not only fail to adequately capture much unreflective decision-making, but also many intentional, reason-based and instrumentally rational choices. Satisfactory folk psychological explanation in fact only comes indirectly from inferring more fundamental conative attitudes from a pattern of decision-theoretic preferences. And the behavioural interpretation does a better job at facilitating such inferences. My argument extends to the related concepts of utility and probability.

This paper argues that instrumental rationality is more permissive than expected utility theory. The most compelling instrumentalist argument in favour of separability, its core requirement, is that agents with non-separable preferences end up badly off by their own lights in some dynamic choice problems. I argue that once we focus on the question of whether agents’ attitudes to uncertain prospects help define their ends in their own right, or instead only assign instrumental value in virtue of the outcomes they may lead to, we see that the argument must fail. Either attitudes to prospects assign non-instrumental value in their own right, in which case we cannot establish the irrationality of the dynamic choice behaviour of agents with non-separable preferences. Or they don’t, in which case agents with non-separable preferences can avoid the problematic choice behaviour without adopting separable preferences.

Judgementalism is an interpretation of normative decision theory according to which preferences are all-things-considered judgements of relative desirability, and the only attitudes that rationally constrain choice. The defence of judgementalism we find in Richard Bradley’s Decision Theory with a Human Face relies on a kind of internalism about the requirements of rationality, according to which they supervene on an agent’s mental states, and in particular those she can reason from. I argue that even if we grant such internalism, attitudes other than preferences in the judgementalist sense rationally constrain choice. This ultimately supports a different interpretation of preference.

Standard decision theory, or rational choice theory, is often interpreted to be a theory of instrumental rationality. This dissertation argues, however, that the core requirements of orthodox decision theory cannot be defended as general requirements of instrumental rationality. Instead, I argue that these requirements can only be instrumentally justified to agents who have a desire to have choice dispositions that are stable over time and across different choice contexts. Past attempts at making instrumentalist arguments for the core requirements of decision theory fail due to a pervasive assumption in decision theory, namely the assumption that the agent’s preferences over the objects of choice – be it outcomes or uncertain prospects – form the standard of instrumental rationality against which the agent’s actions are evaluated. I argue that we should instead take more basic desires to be the standard of instrumental rationality. But unless agents have a desire to have stable choice dispositions, according to this standard, instrumental rationality turns out to be more permissive than orthodox decision theory.

This article argues that Lara Buchak’s risk-weighted expected utility (REU) theory fails to offer a true alternative to expected utility theory. Under commonly held assumptions about dynamic choice and the framing of decision problems, rational agents are guided by their attitudes to temporally extended courses of action. If so, REU theory makes approximately the same recommendations as expected utility theory. Being more permissive about dynamic choice or framing, however, undermines the theory’s claim to capturing a steady choice disposition in the face of risk. I argue that this poses a challenge to alternatives to expected utility theory more generally.

In the dynamic choice literature, temptations are usually understood as temporary shifts in an agent’s preferences. What has been puzzling about these cases is that, on the one hand, an agent seems to do better by her own lights if she does not give into the temptation, and does so without engaging in costly commitment strategies. This seems to indicate that it is instrumentally irrational for her to give into temptation. On the other hand, resisting temptation also requires her to act contrary to the preferences she has at the time of temptation. But that seems to be instrumentally irrational as well. I here consider the two most prominent types of argument why resisting temptation could nevertheless be instrumentally rational, namely two-tier and intra-personal cooperation arguments. I establish that the arguments either fail or are redundant. In particular, the arguments fail under the pervasive assumption in both decision theory and the wider literature on practical rationality that the agent’s preferences over the objects of choice are themselves the standard of instrumental rationality. And they either still fail or they become redundant when we give up that assumption.

Risk-weighted expected utility theory is motivated by small-world problems like the Allais paradox, but it is a grand-world theory by nature. And, at the grand-world level, its ability to handle the Allais paradox is dubious. The REU model described in Risk and Rationality turns out to be risk-seeking rather than risk-averse on one natural way of formulating the Allais gambles in the grand-world context. This result illustrates a general problem with the case for REU theory, we argue. There is a tension between the small-world thinking marshaled against standard expected utility theory, and the grand-world thinking inherent to the risk-weighted alternative.

Some scientists are happy to follow in the footsteps of others; some like to explore novel approaches. It is tempting to think that herein lies an epistemic division of labor conducive to overall scientific progress: the latter point the way to fruitful areas of research, and the former more fully explore those areas. Weisberg and Muldoon’s model, however, suggests that it would be best if all scientists explored novel approaches. I argue that this is due to implausible modeling choices, and I present an alternative ‘epistemic landscape’ model that demonstrates the alleged benefits from division of labor, with one restriction

Most papers in theoretical economics contain thought experiments. They take the form of more informal bits of reasoning that precede the presentation of the formal, mathematical models these papers are known for. These thought experiments differ from the formal models in various ways. In particular, they do not invoke the same idealized assumptions about the rationality, knowledge, and preferences of agents. The presence of thought experiments in papers that present formal models, and the fact that they differ from the formal models in this way, is often ignored in debates on what, if anything, we can learn from formal models in theoretical economics. I show that paying due attention to thought experiments in theoretical economics has serious implications for this debate. Differences between thought experiments and formal models are especially problematic for Robert Sugden’s “credible worlds” account

The question of what a group of rational agents would agree on were they to deliberate on how to organise society is central to all hypothetical social contract theories. If morality is to be based on a social contract, we need to know the terms of this contract. One type of social contract theory, contractarianism, aims to derive morality from rationality alone. Contractarians need to show, amongst other things, that rational and self-interested individuals would agree on an impartial division of a cooperative surplus. But it is often claimed that contractarians cannot show this without introducing moral assumptions. This paper argues that on the right understanding of the question contractarians are asking, these worries can be answered. Without relying on moral assumptions, the paper offers a novel derivation of symmetry, which is the axiom responsible for the impartiality of the most famous economic bargaining solutions appealed to by contractarians