Summary: Human progress depends on shared moral ground, yet people differ widely in what they see as right and wrong. Morality is neither fixed nor arbitrary. Instead, modern psychology shows that morality arises from evolved tendencies that vary across individuals and cultures. Understanding the psychological origins of moral foundations—and the trade-offs they entail—helps to illuminate today’s political divides and offers a path toward healthier discourse and more resilient progress.
Human progress depends on some shared understanding of what “progress” actually means. That understanding is grounded in our moral psychology—how we think about morality and what we see as moral or immoral. For millennia, people have debated what the right morals ought to be, but morality is not a unitary construct. Some philosophers have therefore abandoned the task of moral prescriptions altogether, opting instead for a philosophy of moral relativism – the view that right and wrong depend on culture or personal choice. At its best, moral relativism acknowledges that there is no universal approach to human flourishing across all contexts, leading to a more nuanced discussion on human progress. At its worst, moral relativism represents a complete disregard for moral constraints.
Postmodernist philosophers, such as Michel Foucault and Jacques Derrida, argued that morality is not objective but rather an arbitrary social construct, one typically shaped and enforced to serve the interests of those in power. This interpretation has disastrous consequences: If morality is nothing more than a mask for power, then justice becomes indistinguishable from domination, and every moral claim is reduced to a struggle for control. The possibility of truth, virtue, or genuine liberty disappears, leaving only competing moral narratives without any objective ethical standards to apply. But that is an extreme and perhaps deliberately provocative position. There exists a more nuanced understanding of moral relativism, grounded in evolutionary psychology, that acknowledges different moral values as real but often involving personal and societal trade-offs.
Experts in the field of personality psychology have proposed the “Big Five” theory, which features a five-factor model of personality measuring extraversion, agreeableness, neuroticism, conscientiousness, and openness to experience. This theory is the dominant explanation describing personality in terms of biologically rooted, independent, stable traits. A similar quintet has been applied to moral psychology: the American social psychologist Jonathan Haidt’s five-factor Moral Foundations Theory. Haidt argues that morality can be understood through five core dimensions shaped by evolutionary concerns: care, fairness, loyalty, authority, and purity.
Just as with personality traits, where individuals can fall on the high or low end of a continuous trait—such as being extraverted, introverted, or somewhere in between—Moral Foundations Theory proposes that both individuals and cultures may differ in their valuation of different moral concerns. Importantly, these factor models of personality and morality do not claim whether it is better or worse to be high or low in a trait. Any configuration of this factor model may be adaptive for survival in different environmental niches, but we have evolved levels of traits that, on average, tend to serve us best.
For instance, the adaptiveness of high or low extraversion can depend on the environment. In a resource-rich, socially interconnected environment, greater sociability can enhance cooperation and access to shared goods; however, in a resource-scarce or unstable setting, less sociability may conserve energy and improve self-reliance. As we are social beings, even the most introverted humans tend to be more extroverted than species that fend for themselves. Even the most isolated adult humans learn to speak a language and depend on others in childhood, demonstrating our fundamental extraversion compared with much of the animal kingdom.
Similarly, moral foundations such as care may seem like an unequivocal good, but they are judged not in absolute terms but relative to the human baseline. Even relatively callous humans tend to be more empathetic than the most empathetic chimpanzees, our notoriously violent evolutionary cousins. Moral Foundations Theory suggests that extreme care can sometimes be disadvantageous. For example, excessive care could lead to expending precious resources on the sick and vulnerable at the expense of the group. A lower care value, however, might make hunters and warriors more effective at feeding and defending the tribe, especially when paired with greater loyalty.
Similarly, while fairness is widely regarded as a moral good, it is also one of the most context-dependent traits. Fairness in opportunity often conflicts with fairness in outcome. A society that rewards merit and effort inevitably produces inequality, while one that enforces equality of outcome risks punishing productivity and innovation. In school, grading everyone equally regardless of performance may appear compassionate, but it undermines excellence. In the workplace, equality in compensation can erode motivation among high performers.
Psychological research shows that moral outrage at unfairness typically stems from perceived deceit, exploitation, or free riding, rather than from unequal outcomes in a meritocracy. For example, in behavioral economics research, participants might play a game where each person starts with a fixed amount of money and decides how much to contribute to a public good, such as a water well. The public good benefits everyone, regardless of individual contributions. When some individuals contribute nothing yet still receive its benefits, others frequently choose to spend their own money to penalize these free riders. Evolutionary psychology suggests that moral outrage toward unfairness, including even the willingness to punish cheaters at a personal cost, is an adaptation that safeguards communal welfare and ensures that exploitation is more costly than cooperation.
Sometimes loyalty is directly at odds with care, fairness, and authority. What do you do if a family member has committed a serious criminal offense? Do you protect them from being discovered, or report them to the authorities? Social psychology research shows that people vary in where their loyalties lie, especially across cultures. People from WEIRD (Western, Educated, Industrialized, Rich and Democratic) societies tend to support legal justice even when it means punishing their kin. In contrast, people from so-called cultures of honor, particularly those in the Middle East, tend to prioritize loyalty to their families over the law.
A useful way to conceptualize the difference between the psychological foundations of loyalty and authority is to consider the extent to which allegiances apply between or within groups. Loyalty is fundamentally an intergroup phenomenon. Evolutionary theory suggests that people from the same family or tribe tend to be loyal to each other but not necessarily to out-groups. From a psychological perspective, betrayal rarely stems from a total lack of loyalty—more often, it indicates conflicting loyalties. For instance, a person might leave one lover to commit to another; a whistleblower might betray their employer out of loyalty to their country; and Jean Valjean steals bread to feed his family. In each case, betrayal is relative to one’s personal judgment regarding who belongs to the ingroup.
Authority, however, pertains to dynamics within groups. People within a family or nation may deserve the same level of loyalty and care but not necessarily the same level of authority. Like primate social groups, human societies are deeply hierarchical. Elders and people with strong skill sets, such as the best hunters in hunter-gatherer tribes, often command the most authority. Respect for authority may stabilize a society, especially in a well-functioning meritocracy. But in corrupt countries, where positions of authority are often held by unworthy individuals, subversion of authority is more adaptive. In all cases, it is adaptive to have a range of personality dispositions in the gene pool and a range of moral dispositions across cultures. This allows humans to adapt to changing environments.
Last is purity, a moral foundation rooted in our behavioral immune system. The emotion of disgust evolved as a protection against pathogens. That is why moral prescriptions regarding purity often extend beyond cleanliness to include restrictions on sexual activity, dietary customs, and rules governing the treatment of outsiders. From an evolutionary perspective, all these practices offer potential benefits, but they can also introduce pathogens. Individuals who value purity tend to avoid novel sources of calories, mating opportunities, and contact with strangers, whereas those who do not prioritize purity may reap the benefits while incurring some risk. Neither is better nor worse in any environment, but most people tend to cluster around a baseline that is, on average, adaptive.
Personality psychology primarily focuses on individual differences in traits such as the Big Five and the Moral Foundations, but personality dynamics also occur at the group level. People literally see the world differently based on their personality, and they form or adhere to ideologies as a function of their psychological disposition. Highly empathetic people tend to be left-wing, while highly conscientious people tend to be right-wing. People with like-minded personalities cluster into groups, and these groups become political.
The same goes for moralizing dispositions, as the Harvard University psychologist Joshua Greene explains in his book, Moral Tribes. Progressives tend to most strongly value moral concerns of care and fairness; conservatives, however, tend to most strongly value loyalty, authority, and purity. As mentioned above, these concerns are neither better nor worse, but each brings with it different problems and trade-offs. As Haidt writes in his book The Coddling of the American Mind, progressive values of care and fairness, when taken to their extremes, can stifle meritocracy and foster fragility in children who have not been adequately challenged under the pretext of care. Similarly, conservative values of loyalty, authority, and purity, when also taken to their extremes, can demand conformity, suppress dissent, and justify exclusion in the name of order.
In today’s polarized landscape, these insights into moral foundations reveal why political debates often feel intractable. Disagreements are not merely about facts; they are about competing moral priorities—care versus loyalty, or fairness versus authority. Each moral value is rooted in evolved psychological dispositions. When one side frames inequality as exploitation and the other frames redistribution as coercion, both are acting from deeply ingrained moral instincts. Recognizing that fact does not eliminate conflict, but it reframes it: A society that understands morality as a set of context-dependent trade-offs among competing values can better resist the extremes of both rigid absolutism and cynical relativism.
Just as with personality traits—where diversity ensures a society has both creative innovators and cautious stabilizers—moral diversity serves an adaptive function. A healthy society requires individuals who emphasize care and fairness to protect the vulnerable, and it needs those who emphasize loyalty, authority, and purity to preserve cohesion and continuity. Neither orientation is superior; each corrects the excesses of the other. Moral relativism, rightly understood, does not imply that all values are equal or arbitrary. Rather, like personality traits, it acknowledges that there is a plethora of legitimate moral concerns that come with their own adaptive trade-offs. In this view, moral truth emerges not from deontology—or a strict rule set—but from a free market of moral ideas where different values can evolve, contend, and refine one another through open discourse. Preservation of that discourse is important not only for a peaceful coexistence between citizens with very different moral viewpoints, but for human progress itself.
