Computational theories should be made with natural language instead of meaningless code.

The target article claims that we should speak in code to understand property, because natural language is too ambiguous. Yet the best computer programmers tell us the opposite: Arbitrary code is too ambiguous, so we should use natural language for variables, functions, and classes. I discuss how meaningless code makes Boyer's theory too enigmatic to properly debate.

Moralistic punishment is not for cooperation.

The theory proposed by Fitouchi et al. misses the core of puritanical morality: Cruel punishment for harmless actions. Punishment is mutually harmful, unlike cooperation which is mutually beneficial. Theories of moral judgment should not obscure this fundamental distinction.

Common knowledge, coordination, and strategic mentalizing in human social life.

People often coordinate for mutual gain, such as keeping to opposite sides of a stairway, dubbing an object or place with a name, or assembling en masse to protest a regime. Because successful coordination requires complementary choices, these opportunities raise the puzzle of how people attain the common knowledge that facilitates coordination, in which a person knows X, knows that the other knows X, knows that the other knows that he knows, ad infinitum. We show that people are highly sensitive to the distinction between common knowledge and mere private or shared knowledge, and that they deploy this distinction strategically in diverse social situations that have the structure of coordination games, including market cooperation, innuendo, bystander intervention, attributions of charitability, self-conscious emotions, and moral condemnation.

How Homo economicus lost her mind and how we can revive her.

The target article by Boyer & Petersen (B&P) contributes a vital message: that people have folk economic theories that shape their thoughts and behavior in the marketplace. This message is all the more important because, in the history of economic thought, Homo economicus was increasingly stripped of mental capacities. Intuitive theories can help restore the mind of Homo economicus.

Equity or equality? Moral judgments follow the money.

Previous research emphasizes people's dispositions as a source of differences in moral views. We investigate another source of moral disagreement, self-interest. In three experiments, participants played a simple economic game in which one player divides money with a partner according to the principle of equality (same payoffs) or the principle of equity (pay-offs proportional to effort expended). We find, first, that people's moral judgment of an allocation rule depends on their role in the game. People not only prefer the rule that most benefits them but also judge it to be more fair and moral. Second, we find that participants' views about equality and equity change in a matter of minutes as they learn where their interests lie. Finally, we find limits to self-interest: when the justification for equity is removed, participants no longer show strategic advocacy of the unequal division. We discuss implications for understanding moral debate and disagreement.

The commitment function of angry facial expressions.

What function do facial expressions have? We tested the hypothesis that some expressions serve as honest signals of subjective commitments-in particular, that angry faces increase the effectiveness of threats. In an ultimatum game, proposers decided how much money to offer a responder while seeing a film clip depicting an angry or a neutral facial expression, together with a written threat that was either inherently credible (a 50-50 split) or less credible (a demand for 70% of the money). Proposers offered greater amounts in response to the less credible threat when it was accompanied by an angry expression than when it was accompanied by a neutral expression, but were unaffected by the expression when dealing with the credible threat. This finding supports the hypothesis that angry expressions are honest signals that enhance the credibility of threats.

Does market competition explain fairness?

The target article by Baumard et al. uses their previous model of bargaining with outside options to explain fairness and other features of human sociality. This theory implies that fairness judgments are determined by supply and demand but humans often perceive prices (divisions of surplus) in competitive markets to be unfair.

Pay Your Debts: Moral Dilemmas of International Debt.

Should a government repay its international debts even if this imposes severe hardships on its citizens? Drawing on moral psychology, we investigate when people think a government is morally obligated to pay its debts. Participants read about a government that has to decide whether to default on its debt payments or cut vital programs. Across conditions, we varied the number of jobs at stake and whether a full or partial default is required to save them. Overall, most participants judged that a government should pay its debt even when the damage to the debtor is greater than the benefit to the lender. As the damage to the debtor became extreme, participants increasingly said the government should default, but they still judged that defaulting is morally wrong. In Experiment 2, we find in a national sample of Americans that political conservatives were more opposed to default than liberals. We discuss implications for policy, public opinion, and public welfare during economic downturns. Supplementary Information: The online version of this article (10.1007/s11109-020-09675-6) contains supplementary material, which is available to authorized users.

The omission strategy.

People are more willing to bring about morally objectionable outcomes by omission than by commission. Similarly, people condemn others less harshly when a moral offense occurs by omission rather than by commission, even when intentions are controlled. We propose that these two phenomena are related, and that the reduced moral condemnation of omissions causes people to choose omissions in their own behavior to avoid punishment. We report two experiments using an economic game in which one participant (the taker) could take money from another participant (the owner) either by omission or by commission. We manipulated whether or not a third party had the opportunity to punish the taker by reducing the taker's payment. Our results indicated that the frequency of omission increases when punishment is possible. We conclude that people choose omissions to avoid condemnation and that the omission effect is best understood not as a bias, but as a strategy.

One-way routes complicate cooperation in migrant crises.

How can countries cooperate to shelter migrants? We use experimental economics to study the distinct challenges of cooperation in migrant crises. We designed an economic game, pass the buck, where participants are leaders of countries who decide whether to shelter migrants or pass them to the next country. We examine the difficulties posed by one-way migration and differences in wealth. We find that leaders sheltered migrants less often when they received them first on a one-way route, compared to when everyone received migrants at the same time. Moreover, the first leader became more likely to shelter migrants when the last country could return them to the first. When one country was wealthier, the wealthy leader sheltered more and the other leaders passed more. We discuss the implications for international cooperation in migrant crises.

Spending too little in hard times.

People's decisions to consume and save resources are critical to their wellbeing. Previous experiments find that people typically spend too much because of how they discount the future. We propose that people's motive to preserve their savings can instead cause them to spend too little in hard times. We design an economic game in which participants can store resources for the future to survive in a harsh environment. A player's income is uncertain and consumption yields diminishing returns within each day, creating tradeoffs between spending and saving. We compare participants' decisions to a heuristic that performed best in simulations. We find that participants spent too much after windfalls in income, consistent with previous research, but they also spent too little after downturns, supporting the resource preservation hypothesis. In Experiment 2, we find that by varying the income stream, the downturn effect can be isolated from the windfall effect. In Experiments 3-4, we find the same downturn effect in games with financial and political themes.

Maimonides' ladder: States of mutual knowledge and the perception of charitability.

Why do people esteem anonymous charitable giving? We connect normative theories of charitability (captured in Maimonides' Ladder of Charity) with evolutionary theories of partner choice to test predictions on how attributions of charitability are affected by states of knowledge: whether the identity of the donor or of the beneficiary is revealed to the other. Consistent with the theories, in Experiments 1-2 participants judged a double-blind gift as more charitable than one to a revealed beneficiary, which in turn was judged as more charitable than one from a revealed donor. We also found one exception: Participants judged a donor who revealed only himself as slightly less, rather than more, charitable than one who revealed both identities. Experiment 3 explains the exception as a reaction to the donor's perceived sense of superiority and disinterest in a social relationship. Experiment 4 found that donors were judged as more charitable when the gift was shared knowledge (each aware of the other's identity, but unsure of the other's awareness) than when it was common knowledge (awareness of awareness). Experiment 5, which titrated anonymity against donation size, found that not even a hundredfold larger gift could compensate for the disapproval elicited by a donor revealing his identity. Experiment 6 showed that participants' judgments of charitability flip depending on whose perspective they take: Observers disapprove of donations that they would prefer as beneficiaries. Together, these experiments provide insight into why people care about how a donor gives, not just how much. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The Communicative Function of Sad Facial Expressions.

What are the communicative functions of sad facial expressions? Research shows that people feel sadness in response to losses but it's unclear whether sad expressions function to communicate losses to others and if so, what makes these signals credible. Here we use economic games to test the hypothesis that sad expressions lend credibility to claims of loss. Participants play the role of either a proposer or recipient in a game with a fictional backstory and real monetary payoffs. The proposers view a (fictional) video of the recipient's character displaying either a neutral or sad expression paired with a claim of loss. The proposer then decided how much money to give to the recipient. In three experiments, we test alternative theories by using situations in which the recipient's losses were uncertain (Experiment 1), the recipient's losses were certain (Experiment 2), or the recipient claims failed gains rather than losses (Experiment 3). Overall, we find that participants gave more money to recipients who displayed sad expressions compared to neutral expressions, but only under conditions of uncertain loss. This finding supports the hypothesis that sad expressions function to increase the credibility of claims of loss.

Ownership Dilemmas: The Case of Finders Versus Landowners.

People sometimes disagree about who owns which objects, and these ownership dilemmas can lead to costly disputes. We investigate the cognitive mechanisms underlying people's judgments about finder versus landowner cases, in which a person finds an object on someone else's land. We test psychological hypotheses motivated directly by three major principles that govern these cases in the law. The results show that people are more likely to favor the finder when the object is in a public space compared to a private space. We find mixed support for the hypothesis that people are less likely to favor a finder who is employed by the landowner. Last, we find no support for the hypothesis that people are more likely to favor finders for objects located above ground compared to below ground. We discuss implications for psychological theories of ownership and potential applications to property law.

Kill or die: Moral judgment alters linguistic coding of causality.

What is the relationship between the language people use to describe an event and their moral judgments? We test the hypothesis that moral judgment and causative verbs rely on the same underlying mental model of people's actions. Experiment 1a finds that participants choose different verbs to describe the major variants of a moral dilemma, the trolley problem, mirroring differences in their wrongness judgments: they described direct harm with a single causative verb (Adam killed the man), and indirect harm with an intransitive verb in a periphrastic construction (Adam caused the man to die). Experiments 1b and 2 separate physical causality from moral valuation by varying whether the victim is a person or animal and whether the harmful action rescues people or inanimate objects. The results show that people's moral judgments lead them to portray a causal event as either more or less direct and intended, which in turn shapes their verb choices. Experiment 3 finds the same basic asymmetry in verb usage in a production task in which participants freely described what happened. (PsycINFO Database Record

Recursive mentalizing and common knowledge in the bystander effect.

The more potential helpers there are, the less likely any individual is to help. A traditional explanation for this bystander effect is that responsibility diffuses across the multiple bystanders, diluting the responsibility of each. We investigate an alternative, which combines the volunteer's dilemma (each bystander is best off if another responds) with recursive theory of mind (each infers what the others know about what he knows) to predict that actors will strategically shirk when they think others feel compelled to help. In 3 experiments, participants responded to a (fictional) person who needed help from at least 1 volunteer. Participants were in groups of 2 or 5 and had varying information about whether other group members knew that help was needed. As predicted, people's decision to help zigzagged with the depth of their asymmetric, recursive knowledge (e.g., "John knows that Michael knows that John knows help is needed"), and replicated the classic bystander effect when they had common knowledge (everyone knowing what everyone knows). The results demonstrate that the bystander effect may result not from a mere diffusion of responsibility but specifically from actors' strategic computations.

People's Judgments About Classic Property Law Cases.

People's judgments about property shape how they relate to other people with respect to resources. Property law cases can provide a valuable window into ownership judgments because disputants often use conflicting rules for ownership, offering opportunities to distinguish these basic rules. Here we report a series of ten studies investigating people's judgments about classic property law cases dealing with found objects. The cases address a range of issues, including the relativity of ownership, finder versus landowner rights, object location, objects below- versus above-ground, mislaid versus lost objects, contracts between landowners and finders, and the distinction between public and private space. The results show nuanced patterns in ownership judgments that are not well-explained by previous psychological theories. Also, people's judgments often conflict with court decisions and legal principles. These empirical patterns can be used to generate and test novel hypotheses about the intuitive logic of ownership.

A memory advantage for property.

People's access to resources depends on their status as the owner of particular items. To respect property, people need to remember who owns which objects. We test the hypothesis that people possess enhanced memory for ownership relations compared to unrelated objects. Participants viewed a sequence of 10 person-object pairs before completing a surprise associative memory test in which they matched each person with the previously paired object. We varied the description of the person-object pairs in the instructions. Across three experiments, participants showed better recall when the person was described as the owner of the object compared to being unrelated. Furthermore, memory for property was better than a physical relation (bumping), whereas it did not differ from mental relations (wanting and thinking). These patterns were observed both for memory of items (Experiments 1 and 2) and perceptual details (Experiment 3). We discuss implications for how people remember other people's property.

The psychology of coordination and common knowledge.

Research on human cooperation has concentrated on the puzzle of altruism, in which 1 actor incurs a cost to benefit another, and the psychology of reciprocity, which evolved to solve this problem. We examine the complementary puzzle of mutualism, in which actors can benefit each other simultaneously, and the psychology of coordination, which ensures such benefits. Coordination is facilitated by common knowledge: the recursive belief state in which A knows X, B knows X, A knows that B knows X, B knows that A knows X, ad infinitum. We test whether people are sensitive to common knowledge when deciding whether to engage in risky coordination. Participants decided between working alone for a certain profit and working together for a potentially higher profit that they would receive only if their partner made the same choice. Results showed that more participants attempted risky coordination when they and their prospective partner had common knowledge of the payoffs (broadcast over a loudspeaker) than when they had only shared knowledge (conveyed to both by a messenger) or private knowledge (revealed to each partner separately). These results support the hypothesis that people represent common knowledge as a distinct cognitive category that licenses them to coordinate with others for mutual gain. We discuss how this hypothesis can provide a unified explanation for diverse phenomena in human social life, including recursive mentalizing, performative speech acts, public protests, hypocrisy, and self-conscious emotional expressions.

A solution to the mysteries of morality.

We propose that moral condemnation functions to guide bystanders to choose the same side as other bystanders in disputes. Humans interact in dense social networks, and this poses a problem for bystanders when conflicts arise: which side, if any, to support. Choosing sides is a difficult strategic problem because the outcome of a conflict critically depends on which side other bystanders support. One strategy is siding with the higher status disputant, which can allow bystanders to coordinate with one another to take the same side, reducing fighting costs. However, this strategy carries the cost of empowering high-status individuals to exploit others. A second possible strategy is choosing sides based on preexisting relationships. This strategy balances power but carries another cost: Bystanders choose different sides, and this discoordination causes escalated conflicts and high fighting costs. We propose that moral cognition is designed to manage both of these problems by implementing a dynamic coordination strategy in which bystanders coordinate side-taking based on a public signal derived from disputants' actions rather than their identities. By focusing on disputants' actions, bystanders can dynamically change which individuals they support across different disputes, simultaneously solving the problems of coordination and exploitation. We apply these ideas to explain a variety of otherwise mysterious moral phenomena.