Lara Buchak

Some hold that expected utility is too restrictive in the way it handles risk. Risk‐weighted expected utility is an alternative that allows decision‐makers to have a range of attitudes toward probabilistic risk. It holds that any attitude within this range is instrumentally rational, since these attitudes represent different, equally good, strategies for taking the means to one's ends. A different challenge to expected utility is that it is too restrictive in the way it handles ambiguity—it requires decision‐makers to have sharp probabilities—and risk‐weighted expected utility shares this restrictive feature. This paper presents a generalization of risk‐weighted expected utility which allows for ambiguity. It defends this theory as a theory of instrumental rationality, and argues that attitudes toward risk and attitudes toward ambiguity each represent different but important features of instrumental rationality.

Risk-weighted expected utility (REU) theory holds that there are many rational ways to relate the utilities of prospects to the utilities of outcomes they comprise, since there are many rational ways to take risk into account. This naturally raises the question of how the goodness of risky prospects relates to the goodness of outcomes they comprise. We canvas several possible answers to this question, and argue that REU theorists should take one prospect to be better than another for an individual only if it is better according to all reasonable ways of taking risk into account. We show that our preferred answer has the resources to respond to a number of problems recently raised for REU in the context of social choice. Our discussion also has lessons for dilemmas in social choice beyond those faced by REU, including dilemmas for prioritarians and population ethicists.

Scripture seems to command actions that our modern moral sensibilities find immoral, which poses a problem for those who take Scripture to be the word of God. Amir Saemi (2024) argues that the commands of Islamic Scripture are legal commands but not moral commands, and that legislating non-optimal laws can sometimes be morally best, if optimal laws are infeasible. Using a formal account of coordination, I evaluate this solution, and show that in order to resolve the problem, Scriptural legislation must not function by introducing rewards and punishments, but instead by creating expectations about what others will do and expect others to do. I argue further that to resolve the problem, we should not think that people have gotten more virtuous; instead, when we examine the process of moral learning, we come to see why legislating non-optimal solutions can sometimes lead people to converge on the optimal one. I close with some potential worries.

This paper introduces a rank-dependent decision theory that allows for, explicitly characterizes, and separates probabilistic risk-aversion and ambiguity-aversion. While these phenomena have previously been given independent treatments by theories that extend expected utility in different ways, we provide a unified treatment that preserves the distinctness of each phenomenon. The unified theory holds that a decision-maker assigns ‘as-if’ probabilities to events: where she holds events to be unambiguous, these probabilities are additive, and where she holds events to be ambiguous, they are non-additive and represent her attitude towards ambiguity. The decision-maker then distorts these as-if probabilities according to her attitude towards probabilistic risk, and uses the new weights to assess acts according to rank-dependent utility. We axiomatize this theory and show that assessments of probability, attitudes towards ambiguity, attitudes towards probabilistic risk, and utilities are all distinct features of preference.

This poster presents results from applying agent-based modeling to an exploration of risk attitudes and rational decision making in the context of group interaction. We are also interested in the place of agent-based modeling and computational philosophy within the computational humanities. Computational philosophy has not typically been included in Digital Humanities; computational work has been done using philosophy texts as a source for analysis (Kinney 2022; Malaterre et al. 2021; Fletcher et al. 2021; Zahorec et al. 2022), but there are few examples of philosophical arguments being made based on computation (Zahorec et al. 2022). Modeling is largely accepted as a computational humanist method (McCarty 2004; So 2022), but typically models are based on data rather than designed simulations as a method analogous to a thought experiment (Mayo-Wilson / Zollman 2021). Agent-based modeling is not as common in computational humanities, but we are interested in its potential; for instance, see work modeling correspondence networks to better understand lost information and biases in correspondence data sets (Buarque / Vogl 2023), or work simulating past human societies (Romanowska et al. 2021). Our project explores Lara Buchak’s theory of risk-weighted rational decision making by extending it to the context of group populations and interactions. Buchak has proposed risk-weighted expected utility maximization, which incorporates individual risk attitudes into the standard expected utility (EU) calculation based on utility and probability of outcomes (Buchak 2017). This theory provides an explanation for differences of behavior seen in human populations, while still allowing those different choices to be rational. Buchak’s theory has previously only been applied to individual decision making; our work uses agent-based modeling to develop and analyze simulations which incorporate a variety of risk attitudes (risk avoidance and risk seeking) into game theoretic interactions. This project is a collaboration between a philosopher and a research software engineer; we have worked together to develop simulations that implement agents with risk attitudes making risky choices. This presentation focuses on results from an implementation of a hawk/dove game with multiple risk attitudes and risk attitude adjustment. In the hawk/dove game cooperation, or playing dove, is better for the population, but acting aggressively, or playing hawk, is better for an individual if they are in a neighborhood of doves. To set up the game, we place agents on a grid and have them play against each of their neighbors, and accumulate payoffs based on the success of their plays. We define risk attitudes 0 through 9, where that number corresponds to the minimum number of neighbors playing dove for an agent to play hawk. An agent with risk attitude 0 is most risk seeking and always plays hawk; an agent with risk attitude 1 will play hawk if at least one neighbor plays dove; an agent with risk attitude 9 always takes the safe choice and plays dove; an agent with risk attitude 4 or 5 is risk neutral (breaking ties in different ways), which corresponds to expected utility. In this simulation we randomly set agent initial risk attitudes, and then every ten rounds agents compare their payoffs with their neighbors and adopt the most successful risk attitude in their neighborhood. The simulation is coded to stop once risk attitude adjustments stabilize. We define 13 different population states based on primary and second majority of risk averse, risk inclined, or risk moderate, and analysis of over 1 million runs indicate that while it’s more likely to stabilize with the population having become majority risk inclined, that is not the only outcome; we also see cases where the population stabilizes as risk neutral, risk avoidant, and many cases with no clear majority. This diversity of stable populations provides support for the argument that no one risk attitude is uniquely rational, but rather that risk attitudes are conventional. This matches what we observe in the real world: that different populations have different risk attitudes. Our simulations include numerous parameters to vary grid size; adjustment frequency, strategy, and wealth comparison; neighborhood sizes for observing previous choice, playing against, and comparing payoffs for adjusting risk attitudes; and different distributions for initializing risk attitudes. Analysis of parameters and adjusted risk attitudes shows that the strongest correlations are the initial distribution of risk attitudes, which tend to be preserved. * * * This poster was accepted and presented at the DH2024 conference in Washington, D.C.

This is the tenth volume of Oxford Studies in Philosophy of Religion. As with earlier volumes, these essays follow the tradition of providing a non-sectarian and non-partisan snapshot of the subdiscipline of philosophy of religion. This subdiscipline has become an increasingly important one within philosophy over the last century, and especially over the past half-century, having emerged as an identifiable subfield at the same time as other emerging subfields such as the philosophy of science and the philosophy of language. This volume continues the initial intention behind the series: attracting the best work from philosophers well known for their work in philosophy of religion, while also including essays by philosophers working mainly in other subfields when their research addresses religious matters. This inclusive approach to the series provides an opportunity to mitigate some of the costs of greater specialization in our discipline, while at the same time inviting wider interest in the work being done in the subfield. Volumes also typically contain the winner of the Sanders Prize in the Philosophy of Religion and other essays submitted to that competition.

In the peer disagreement debate, three intuitively attractive claims seem to conflict: there is disagreement among peers on many important matters; peer disagreement is a serious challenge to one’s own opinion; and yet one should be able to maintain one’s opinion on important matters. I show that contrary to initial appearances, we can accept all three of these claims. Disagreement significantly shifts the balance of the evidence; but with respect to certain kinds of claims, one should nonetheless retain one’s beliefs. And one should retain them even though these beliefs would not be supported by the new total evidence if one didn’t already hold them.

Suppose we want to do the most good we can with a particular sum of money, but we cannot be certain of the consequences of different ways of making use of it. This article explores how our attitudes towards risk and ambiguity bear on what we should do. It shows that risk-avoidance and ambiguity-aversion can each provide good reason to divide our money between various charitable organizations rather than to give it all to the most promising one. It also shows how different attitudes towards risk and ambiguity affect whether we should give to an organization which does a small amount of good for certain or to one which does a large amount of good with some small or unknown probability.

Certain ethical views hold that we should pay more attention, even exclusive attention, to the worst-case scenario. Prominent examples include Rawls's Difference Principle and the Precautionary Principle. These views can be anchored in formal principles of decision theory, in two different ways. On the one hand, they can rely on ambiguity-aversion: the idea that we cannot assign sharp probabilities to various scenarios, and that if we cannot assign sharp probabilities, we should decide pessimistically, as if the probabilities are unfavorable. On the other hand, they can rely on risk-avoidance: the idea that we should pay more attention to worse scenarios, even when we can assign sharp probabilities. I distinguish these two foundations. I also show how they can be modified to support versions of these views that pay more but not exclusive attention to worst-case scenarios. Finally, I argue that risk-avoidance provides a superior foundation than ambiguity-aversion for the Difference Principle and the Precautionary Principle; in particular, it correctly identifies which ethical facts should matter to those who champion these principles.

One phenomenon arising in epistemic life is allegiance to, and break from, a tradition. This phenomenon has three central features. First, individuals who adhere to a tradition seem to respond dogmatically to evidence against their tradition. Second, individuals from different traditions appear to see the same evidence differently. And third, conversion from one tradition to another appears to be different in kind from ordinary belief shift. This paper uses recent work on the nature and rationality of faith to show that these features can all emerge from individuals acting rationally—in particular, from individuals rationally having faith in the core assumptions of their traditions. One upshot is that we don't need to employ the idea of incommensurability to explain these features.

The good of those who are worse off matters more to the overall good than the good of those who are better off does. But being worse off than one’s fellows is not itself bad; nor is inequality itself bad; nor do differences in well-being matter more when well-being is lower in an absolute sense. Instead, the good of the relatively worse-off weighs more heavily in the overall good than the good of the relatively better-off does, in virtue of the fact that the former are relatively worse off. This paper articulates and defends the view just described.

How do scientific explanations for beliefs affect people's confidence that those beliefs are true? For example, do people think neuroscience-based explanations for belief in God support or challenge God's existence? In five experiments, we find that people tend to think explanations for beliefs corroborate those beliefs if the explanations invoke normally-functioning mechanisms, but not if they invoke abnormal functioning (where “normality” is a matter of proper functioning). This emerges across a variety of kinds of scientific explanations and beliefs (religious, moral, and scientific). We also find evidence that these effects can interact with people's prior beliefs to produce motivated judgments.

Within philosophy of action, there are three broad views about what, in addition to beliefs, answer the question of “what to do?” and so determine an agent’s motivation: desires, judgments about values/reasons, or states of the will, such as intentions. We argue that recent work in decision theory vindicates the volitionalist. “What to do?” isn’t settled by “what do I value” or “what reasons are there?” Rational motivation further requires determining how to trade off the possibility of a good outcome against the possibility of a bad one—i.e., determining how much of a risk to take. The risk attitudes that embody this tradeoff seem best understood as intentions: as self-governing policies to weight desires or reasons in certain ways. That we need to settle our risk attitudes before making most decisions corroborates Bratman’s claim that self-governing policies are required for resolving impasses of evaluative and normative underdetermination. Moreover, far from being rare or confined to tie-breakings, cases that are underdetermined but for one’s risk attitudes are typical of everyday decision-making. The will is required for most rational action.

This essay argues that when setting climate policy, we should place more weight on worse possible consequences of a policy, while still placing some weight on better possible consequences. The argument proceeds by elucidating the range of attitudes people can take towards risk, how we must make choices for people when we don’t know their risk-attitudes, and the situation we are in with respect to climate policy and the consequences for future people. The result is an alternative to the Precautionary Principle, an alternative that gives similar policy recommendations in many cases but is also sensitive to the costs of precautions.

How should a group with different opinions (but the same values) make decisions? In a Bayesian setting, the natural question is how to aggregate credences: how to use a single credence function to naturally represent a collection of different credence functions. An extension of the standard Dutch-book arguments that apply to individual decision-makers recommends that group credences should be updated by conditionalization. This imposes a constraint on what aggregation rules can be like. Taking conditionalization as a basic constraint, we gather lessons from the established work on credence aggregation, and extend this work with two new impossibility results. We then explore contrasting features of two kinds of rules that satisfy the constraints we articulate: one kind uses fixed prior credences, and the other uses geometric averaging, as opposed to arithmetic averaging. We also prove a new characterisation result for geometric averaging. Finally we consider applications to neighboring philosophical issues, including the epistemology of disagreement

The ‘rollback argument,’ pioneered by Peter van Inwagen, purports to show that indeterminism in any form is incompatible with free will. The argument has two major premises: the first claims that certain facts about chances obtain in a certain kind of hypothetical situation, and the second that these facts entail that some actual act is not free. Since the publication of the rollback argument, the second claim has been vehemently debated, but everyone seems to have taken the first claim for granted. Nevertheless, the first claim is totally unjustified. Even if we accept the second claim, therefore, the argument gives us no reason to think that free will and indeterminism are incompatible. Furthermore, seeing where the rollback argument goes wrong illuminates how a certain kind of incompatibilist, the ‘chance-incompatibilist,’ ought to think about free will and chance, and points to a possibility for free will that has remained largely unexplored.

Does postulating skeptical theism undermine the claim that evil strongly confirms atheism over theism? According to Perrine and Wykstra, it does undermine the claim, because evil is no more likely on atheism than on skeptical theism. According to Draper, it does not undermine the claim, because evil is much more likely on atheism than on theism in general. I show that the probability facts alone do not resolve their disagreement, which ultimately rests on which updating procedure – conditionalizing or updating on a conditional – fits both the evidence and how we ought to take that evidence into account.

I have claimed that risk-weighted expected utility maximizers are rational, and that their preferences cannot be captured by expected utility theory. Richard Pettigrew and Rachael Briggs have recently challenged these claims. Both authors argue that only EU-maximizers are rational. In addition, Pettigrew argues that the preferences of REU-maximizers can indeed be captured by EU theory, and Briggs argues that REU-maximizers lose a valuable tool for simplifying their decision problems. I hold that their arguments do not succeed and that my original claims still stand. However, their arguments do highlight some costs of REU theory.