Common reasoning in games: A Lewisian analysis of common knowledge of rationality

The game-theoretic assumption of common knowledge of rationality leads to paradoxes when rationality is represented in a Bayesian framework as cautious expected utility maximisation with independent beliefs (ICEU). We diagnose and resolve these paradoxes by presenting a new class of formal models of players' reasoning, inspired by David Lewis's account of common knowledge, in which the analogue of common knowledge is derivability in common reason. We show that such models can consistently incorporate any of a wide range of standards of decision-theoretic practical rationality. We investigate the implications arising when the standard of decision-theoretic rationality so assumed is ICEU

Moral Judgments in Social Dilemmas: How Bad is Free Riding?

In the last thirty years, economists and other social scientists have investigated people’s normative views on distributive justice. Here we study people’s normative views in social dilemmas, which underlie many situations of economic and social significance. Using insights from moral philosophy and psychology we provide an analysis of the morality of free riding. We use experimental survey methods to investigate people’s moral judgments empirically. We vary others’ contributions, the framing (“give-some” vs. “take-some”) and whether contributions are simultaneous or sequential. We find that moral judgments of a free rider depend strongly on others’ behaviour; and that failing to give is condemned more strongly than withdrawing all support.moral judgments, moral psychology, framing effects, public goods experiments, free riding

Moral Judgments in Social Dilemmas: How Bad is Free Riding?

In the last thirty years, economists and other social scientists have investigated people’s normative views on distributive justice. Here we study people’s normative views in social dilemmas, which underlie many situations of economic and social significance. Using insights from moral philosophy and psychology we provide an analysis of the morality of free riding. We use experimental survey methods to investigate people’s moral judgments empirically. We vary others’ contributions, the framing (“give-some” vs. “take-some”) and whether contributions are simultaneous or sequential. We find that moral judgments of a free rider depend strongly on others’ behaviour; and that failing to give is condemned more strongly than withdrawing all support.moral judgments, moral psychology, framing effects, public goods experiments, free riding

Conditional Cooperation and Betrayal Aversion

We investigate whether there is a link between conditional cooperation and betrayal aversion. We use a public goods game to classify subjects by type of contribution preference and by belief about the contributions of others; and we measure betrayal aversion for different categories of subject. We find that, among conditional cooperators, only those who expect others to contribute little to the public good are significantly betrayal averse, while there is no evidence of betrayal aversion for those who expect substantial contributions by others. This is consistent with their social risk taking in public goods games, as the pessimistic conditional cooperators tend to avoid contribution to avoid exploitation, whereas the optimistic ones typically contribute to the public good and thus take the social risk of being exploited

Common reasoning in games: a Lewisian analysis of common knowledge of rationality

Abstract: We present a new class of models of players’ reasoning in non-cooperative games, inspired by David Lewis’s account of common knowledge. We argue that the models in this class formalise common knowledge of rationality in a way that is distinctive, in virtue of modelling steps of reasoning; and attractive, in virtue of being able to represent coherently common knowledge of any consistent standard of individual decision-theoretic rationality. We contrast our approach with that of Robert Aumann (1987), arguing that the former avoids and diagnoses certain paradoxes to which the latter may give rise when extended in particular ways

On preference imprecision

Recent research invokes preference imprecision to explain violations of individual decision theory. While these inquiries are suggestive, the nature and significance of such imprecision remain poorly understood. We explore three questions using a new measurement tool in an experimental investigation of imprecision in lottery valuations: Does such preference imprecision vary coherently with lottery structure? Is it stable on repeat measurement? Does it have explanatory value for economic behaviour? We find that imprecision behaves coherently, shows no tendency to change systematically with experience, is related to choice variability, but is not a main driver of the violations of standard decision theory that we consider

Credit Constraints and the Measurement of Time Preferences

Incentivized experiments are commonly used to estimate marginal rates of intertemporal substitution (MRS) in the lab and in the field in order to make inferences about individual time preferences. This paper considers an integrated model of behavior in which individuals are subject to financial shocks and credit constraints, and take those into account when making experimental choices. The model shows that measured MRS depends on the individual’s effective interest rate which is equal to the relative marginal utility of current and future consumption. Experimental responses should therefore be correlated with other variables that describe the subject’s financial situation, like savings and shocks to income and consumption. We test the model using a new a panel data set from Mali and find evidence for such effects. Our results imply that the relationship between experimentally elicited MRS and time preferences is not straightforward. However, measured MRS can be useful in determining the importance of different types of financial shocks to the household

Dynamic Choice under Ambiguity

This paper analyzes sophisticated dynamic choice for ambiguity-sensitive decision makers. It characterizes Consistent Planning via axioms on preferences over decision trees. Furthermore, it shows how to elicit conditional preferences from prior preferences. The key axiom is a weakening of Dynamic Consistency, deemed Sophistication. The analysis accommodates arbitrary decision models and updating rules. Hence, the results indicate that (i) ambiguity attitudes, (ii) updating rules, and (iii) sophisticated dynamic choice are mutually orthogonal aspects of preferences. As an example, a characterization of prior-by-prior Bayesian updating and Consistent Planning for arbitrary maxmin-expected utility preferences is presented. The resulting sophisticated MEU preferences are then used to analyze the value of information under ambiguity; a basic trade-off between information acquisition and commitment is highlighted

Functional antibody and T-cell immunity following SARS-CoV-2 infection, including by variants of concern, in patients with cancer: the CAPTURE study

Patients with cancer have higher COVID-19 morbidity and mortality. Here we present the prospective CAPTURE study (NCT03226886) integrating longitudinal immune profiling with clinical annotation. Of 357 patients with cancer, 118 were SARS-CoV-2-positive, 94 were symptomatic and 2 patients died of COVID-19. In this cohort, 83% patients had S1-reactive antibodies, 82% had neutralizing antibodies against WT, whereas neutralizing antibody titers (NAbT) against the Alpha, Beta, and Delta variants were substantially reduced. Whereas S1-reactive antibody levels decreased in 13% of patients, NAbT remained stable up to 329 days. Patients also had detectable SARS-CoV-2-specific T cells and CD4+ responses correlating with S1-reactive antibody levels, although patients with hematological malignancies had impaired immune responses that were disease and treatment-specific, but presented compensatory cellular responses, further supported by clinical. Overall, these findings advance the understanding of the nature and duration of immune response to SARS-CoV-2 in patients with cancer