Piaget proposed that young children do not realize that moral rules can vary across people and cultures. Older children undergo a shift from realism to relativism. They come to understand that some moral rules are cultural conventions, not absolute truths. They undergo a second shift from prescriptions to principles in which they recognize that moral rules are expressions of general principles, such as fairness and avoiding harm to others. In the final shift, children begin to distinguish outcomes from intentions, considering people's intentions when judging the morality of an act. For example, harming someone intentionally is judged more harshly than harming someone accidentally, even if the injury is identical.
Lawrence Kohlberg proposed a theory of moral development consisting of six stages divided into three levels. At the preconventional level, infants and toddlers want to avoid punishment, whereas preschoolers want to please others for their own benefit. At the conventional level, school-aged children learn that authorities establish certain conventions that govern how they should and should not behave. At the post-conventional level, an individual learns the difference between right and wrong from a broader moral perspective. Teens adopt a code of morality based on principles of mutual benefits and reciprocity. Adults develop a moral code that transcends mutual benefits, focusing on principles such as justice. In this stage, people may justify violating social conventions to serve a higher purpose. Not all people reach this post-conventional stage of morality.
Kohlberg’s Theory of Moral Development
| Level | Stage | Developmental Phase | Description |
|---|---|---|---|
| Preconventional | Obedience and punishment | Infancy | Right and wrong is defined by punishment |
| Self-interest and relativism | Preschool | Right and wrong begins to shift toward rewards and self-interest | |
| Conventional | Conformity and interpersonal relationships | School-age | Conforming to please others, with right and wrong defined by the majority |
| Authority and social order | School-age | Right and wrong is defined by duty to society and obeying laws | |
| Post-conventional | Social contract | Adolescence | Right and wrong is defined by personal values and mutual benefit |
| Universal principles | Adulthood | Right and wrong is based on moral principles over mutual benefit |
According to Kohlberg, people's approach to morality changes throughout the lifespan, although not everyone reaches the highest stages of moral development.
Early theories of moral development assumed the ability to reason about right and wrong emerged gradually from infancy to adulthood. Modern scientific findings suggest otherwise. Infants as young as six months can distinguish between prosocial actions (helping, sharing) and antisocial actions (hindering, harming), and they prefer individuals who engage in prosocial actions. When given the choice to accept a smaller offering from a prosocial individual or a larger offering from an antisocial individual, school-aged children and infants as young as 12 months choose to accept the smaller offering. By the second year of life, toddlers expect reciprocity (mutual exchange) in social interactions. By the third year, they distinguish between moral rules and social conventions. Infants and toddlers also expect people to behave better toward members of their own group.
Moral dilemmas are the cornerstone of modern research on moral reasoning. The classic trolley problem is one of the most researched dilemmas. In the trolley problem, a person must decide whether to divert a runaway trolley to save five people, knowing that diverting the trolley will kill one person. By systematically varying features of this problem, researchers have tested different theories of moral reasoning. According to an influential dual-process model proposed by Joshua Greene, moral judgment is the outcome of a rapid, emotion-laden process and a slower, deliberative process. If these outputs conflict, decision time increases to resolve the discrepancy. Moral judgment is therefore a combination of emotion and reason.
An alternative theory proposed by American social psychologist Jonathan Haidt, called the social intuitionist theory, claims moral judgment is like aesthetic judgment: people see an action or hear a story and have an instant sense of approval or disapproval. Deliberative reasoning takes place later, usually to justify a moral judgment that has already been made. Haidt's cross-cultural research revealed several different psychological foundations to morality upon which human cultures construct their moral communities. The moral domain of educated Westerners is narrower—focused primarily on harm, freedom, and fairness. Other cultures give more consideration to purity, authority, and loyalty. Moral judgments also vary across the political spectrum.