This chapter of the handbook discusses the complex, multifaceted connection between morality and religion from an evolutionary perspective. After providing some much-needed conceptual ground clearing, the authors focus on accounts of the linkage between morality and religion in terms of evolved psychological mechanisms that promote cooperation and inhibit competition. One of the better known of these accounts is the supernatural punishment hypothesis. On this view, the morality–religion link is sustained by the fact that belief in an all-knowing, all-powerful god who monitors people’s behavior and punishes their moral transgressions motivates people to behave less selfishly and more cooperatively. Another account emphasizes religious behavior and posits that participation in religious ritual is a form of costly signaling, indicating to others that the participant can be trusted to observe the moral norms of the community. While there is considerable support for the idea that aspects of religion function to curb selfishness, however, the authors caution that the psychological and sociological mechanisms underlying this function are not yet well understood.

This chapter of the handbook takes up the issue of moral development in adolescence. The authors’ wide-ranging discussion touches on how differences in temperament, gender, familial and peer relationships, and lived experience influence the timing and outcome of adolescent moral development. Regarding the role of temperament, for example, high-reactive individuals may be more prone to impulsive behavior that violates moral norms, whereas low-reactive individuals may be more likely to conform to moral norms because they are more sensitive to the threat of punishment. On the importance of interpersonal relationships, weak attachment to caregivers in adolescence is associated with impairments of empathy and a greater propensity for antisocial and immoral behavior. Peer influence is another key predictor of both antisocial and prosocial behavior in adolescence. Further, moral development in adolescence critically depends on the maturation of capacities for empathy and self-conscious emotion, a process that is shaped by the individual’s lived experience.

This chapter of the handbook consists of a two-part discussion of moral communication, highlighting the topic of punishment. In the first part, the authors focus on what makes human forms of communication distinctive, whether linguistic or nonlinguistic, and on what distinguishes moralized norms from normative attitudes and behaviors. They argue that the transgression of moralized norms is distinctive in that it tends to provoke a strong desire to punish transgressors, where such punishment has a communicative dimension. In the second part, the authors review psychological research on why people punish and discuss its communicative aspects. They propose that a communicative framework not only resolves major ongoing debates between traditional camps (retributive vs. consequentialist) but also potentially accounts for some otherwise puzzling findings. Studying the symbolic meaning of punishment along with its intended recipients opens up promising new avenues for research into factors that could modulate people‘s taste for punishment.

This chapter proposes a way to investigate and evaluate the moral standing of cultural customs different from one’s own without falling into ethnocentrism. As a methodological approach the authors adopt the perspective of “moral realism,” which is the view that there are absolute moral truths that supply all human beings with good reasons for their judgments about what is right or wrong and possess a normative authority that supersedes social consensus and personal desire. According to the authors genuine moral absolutes are abstract forms that provide the skeletal structure for the development of any genuinely moral cultural tradition; while it is their fate to be specified and implemented locally and to assume an historically provincial moral shape. To illustrate this relationship between moral reality and cultural specificity, the authors analyze several ethnographic examples of distinctive and even clashing moral traditions. These include clashes between Brahman Hindu Indian and Western secular views of a widow’s obligations and tensions between Native American whalers’ and whaling protesters’ attitudes toward whaling.

This chapter of the handbook posits utilitarianism as a standard of rational moral judgment. The author does not directly defend utilitarianism as a theory but investigates cases of apparent contradiction between people’s moral decisions (sometimes grounded in nonutilitarian principles) and the consequences of those decisions that they themselves would consider worse for themselves and everybody else. For example, when some people use a moral principle (e.g., bodily autonomy) to assertively make a decision (e.g., to not get vaccinated), it has negative moral consequences for others (e.g., infecting people) and for themselves (risking infection). The author asks whether such contradictions in moral reasoning can provide insights into some of the determinants of such reasoning. These insights, importantly, are valuable even for those who do not adopt utilitarianism as a normative model. From over a dozen candidate moral contradictions, the author concludes that many deviations from utilitarian considerations in moral contexts are reflections of familiar nonmoral cognitive biases, but some arise from adherence to strong moral rules or principles (e.g., protected or sacred values).

This chapter of the handbook tackles a foundational question in moral psychology: What constitutes the moral domain? To answer this question, we first have to know how our minds determine right from wrong. The authors argue that our intuitive, culturally flexible perceptions of harm drive our judgments of the moral domain. This is not the dominant view of the moral domain, but the most popular models of the past and present need not be the most accurate ones. Instead, these paradigms reflect broader shifts in our values as a society and a field of research. The Turielian moral domain of the 1970s and 1980s took inspiration from the cognitive revolution, positing harm as a universal value that fully determines how people decide right from wrong. The Haidtian paradigm of today is influenced by the rise of cross-cultural psychology, arguing that harm is just one of many intuitive, culturally activated moral values. Ultimately, neither paradigm gets it completely right, but the authors argue that we can build a better paradigm by combining the strengths of each. In this model, harm is the key driver of moral judgments, but perceptions of harm are intuitive and culturally variable.

This chapter of the handbook introduces some core elements of moral decision making by framing it from one particular perspective: expected utility theory. In its classic form, expected utility theory focuses on the outcomes of actions: the expected utility of a decision is the sum of the values associated with the different possible outcomes of the decision weighted by the probability of their occurrence. As such, expected utility theory is well suited to explain the moral choices recommended by utilitarianism, which characterizes right actions in terms of the maximization of aggregate utility. As the authors point out, however, expected utility theory can be also used to model nonutilitarian decision making by assigning utilities to actions themselves, not just their outcomes. This action-based form of expected utility theory can readily accommodate the fact that people tend to assign low utility to actions that violate moral norms. Further, action-based expected utility theory can explain a wide range of phenomena revealed by empirical research on moral decision making, such as interpersonal disagreement about fairness, in-group bias, and outcome neglect.

This chapter of the handbook suggests some lessons from moral psychology for ethics and metaethics. The authors note that empirical research on a wide range of topics, including moral character, happiness and well-being, free will and moral responsibility, and moral judgment, has had a profound influence on recent philosophical theorizing about the foundations of morality. In their chapter they focus on one issue of particular importance: the reliability and trustworthiness of moral judgment. They critically assess three lines of argument that threaten to undermine epistemic confidence in our moral judgments, namely process debunking arguments, arguments from disagreement, and arguments from irrelevant influences. Though the jury is still out on how successful these arguments are, there is little question that they have potentially profound implications both for moral epistemology and philosophical methodology. Perhaps the most important lesson for ethics and metaethics to be drawn from moral psychology, then, may be that future progress in moral philosophy is likely to depend on philosophers and psychologists working together, rather than in isolation from one another.

This chapter of the handbook discusses the moral dimensions of political attitudes and behavior. The authors argue that a person’s political views – both at the level of political ideology as a whole and views on specific matters of economic and social policy – are profoundly shaped by their beliefs about right and wrong. These political views in turn drive people’s political behavior, not just at the ballot box or on the campaign trail, but in the community more generally. One downside of the way in which moral convictions fuel political attitudes and behavior is that they tend to interfere with productive communication across partisan divides, fueling a kind of animosity that stifles cooperation and compromise. Divergence in people’s moral convictions, then, leads inexorably to political polarization and gridlock. To address this problem, the authors discuss a number of potentially promising interventions, some of which target individuals’ attitudes (e.g., promoting empathy, reducing negative stereotypes), and others that aim at improving the quality of interpersonal relationships (e.g., increasing contact, fostering dialogue across political divides).

This chapter of the handbook examines the foundational role of norms in moral psychology, a topic that has long garnered cross-disciplinary interest from philosophy to biology, from anthropology to computer science. The authors touch briefly on the debates over potentially different types of norm (e.g., conventional, social, moral, legal) and maintain that social and moral norms, in particular, are difficult to separate unless one adopts a specific theoretical position. The authors’ treatment centers on a core feature of most or all social and moral norms: that people, in complying or not complying with norms, are sensitive to other community members’ norm-relevant beliefs and attitudes. By recognizing this sensitivity, scientists can, first, gain a better scientific understanding of norm inference, the complex processes by which people learn which norms apply to a given setting and how strong the norms are; and second, they can better diagnose whether (and how strongly) a given norm exists in a community. All these insights pave the way for potential interventions on people’s beliefs about the community’s norms, which are easier to change than individual moral convictions.

This chapter of the handbook introduces readers to the field of moral psychology as a whole and provides them with a guide to the volume. The authors delineate the landscape of morality in terms of five phenomena extensively studied by moral psychologists: moral behavior, moral judgments, moral sanctions, moral emotions, and moral communication, all against a background of moral standards. They then provide brief overviews of research on a few topics not assigned a dedicated chapter in the book (e.g., the moral psychology of artificial intelligence, free will, and moral responsibility), noting several other topics not treated in depth (e.g., the neuroscience of morality, links between moral and economic behavior, moral learning). In the last section of the chapter, the authors summarize each of the contributed chapters in the book.

This chapter of the handbook presents a large body of evidence suggesting that, within the first year of life, infants hold both expectations about and preferences for morally good versus bad protagonists. The authors show that, across different methods, infants distinguish between morally significant acts of helping and hindering as well as between acting fairly and unfairly; they prefer the morally good actions and the morally good protagonists; and they expect others to prefer the morally good protagonists as well. Going beyond a mere valence difference, these expectations vary systematically in response to critical factors, such as the victim’s state of need, in-group/out-group membership, and an actor’s intentions. Many of the findings appear in infants 8–12 months of age, some as early as 3 months of age. Many questions remain, such as how consistent the findings are across experimenters and populations; whether the violated norm is truly moral or only a social expectation; or to what extent earliest learning guides these expectations and preferences. But overall, the evidence for budding moral distinctions in early infancy is highly compelling and provocative.

This chapter of the handbook highlights that, for successful social living, humans’ capacity to be prosocial had to surpass their capacity for selfish and harmful behavior. The authors provide an overview of the scientific study of prosocial capacities, with a focus on experimental research. Summarizing extensive work in laboratory paradigms of behavioral economics and social psychology, the authors document a strong human tendency toward behaving prosocially. They then briefly examine the phylogenetic and developmental origins of behaving prosocially and its different motives, such as reputational concerns and caring for others, as well as emotions that facilitate prosocial behavior, such as empathy or guilt. The authors also summarize insights from cognitive neuroscience on the brain networks that undergird prosocial behavior. They close with a call for more naturalistic experimental paradigms and the consideration of temporal dynamics of prosocial behavior.

This chapter of the handbook proposes a developmental ethics, an organic moral theory grounded in (1) humanity’s deep evolutionary history, (2) the malleability of the child’s neurobiological structures that undergird moral functioning, and (3) the influence of cultural practices on neurobiological development. The chapter addresses the following questions: What kind of creature are we? What qualities do we need to live a full life? What kinds of capacities make each a proper member of the species? What influences our development? Answers center around perhaps the most critical influence on human development, our species’ evolved nest. In humanity’s ancestral context, nestedness is a lifelong experience with particular import in early life. Moral virtue emerges from holistically coordinated physiological, psychological, spiritual systems oriented toward holistic communal harmony, social attunement, receptivity, and interpersonal flexibility. Understanding how the evolved nest scaffolds biopsychosocial and moral development reveals why antisocial behavior is so pervasive in modern Western culture – and it provides a baseline for redesigning society to promote prosociality.