I began to study morality and culture at the University of Pennsylvania in 1987. A then-prevalent definition of the moral domain, from the Berkeley psychologist Elliot Turiel, said that morality refers to "prescriptive judgments of justice, rights, and welfare pertaining to how people ought to relate to each other." But if morality is about how we treat each other, then why did so many ancient texts devote so much space to rules about menstruation, who can eat what, and who can have sex with whom? There is no rational or health-related way to explain these laws. (Why are grasshoppers kosher but most locusts are not?) The emotion of disgust seemed to me like a more promising explanatory principle. The book of Leviticus makes a lot more sense when you think of ancient lawgivers first sorting everything into two categories: "disgusts me" (gay male sex, menstruation, pigs, swarming insects) and "disgusts me less" (gay female sex, urination, cows, grasshoppers ).

For my dissertation research, I made up stories about people who did things that were disgusting or disrespectful yet perfectly harmless. For example, what do you think about a woman who can't find any rags in her house so she cuts up an old American flag and uses the pieces to clean her toilet, in private? Or how about a family whose dog is killed by a car, so they dismember the body and cook it for dinner? I read these stories to 180 young adults and 180 eleven-year-old children, half from higher social classes and half from lower, in the USA and in Brazil. I found that most of the people I interviewed said that the actions in these stories were morally wrong, even when nobody was harmed. Only one group—college students at Penn—consistently exemplified Turiel's definition of morality and overrode their own feelings of disgust to say that harmless acts were not wrong. (A few even praised the efficiency of recycling the flag and the dog).

This research led me to two conclusions. First, when gut feelings are present, dispassionate reasoning is rare. In fact, many people struggled to fabricate harmful consequences that could justify their gut-based condemnation. I often had to correct people when they said things like "it's wrong because… um…eating dog meat would make you sick" or "it's wrong to use the flag because… um… the rags might clog the toilet." These obviously post-hoc rationalizations illustrate the philosopher David Hume's dictum that reason is "the slave of the passions, and can pretend to no other office than to serve and obey them." This is the first rule of moral psychology: feelings come first and tilt the mental playing field on which reasons and arguments compete. If people want to reach a conclusion, they can usually find a way to do so. The Democrats have historically failed to grasp this rule, choosing uninspiring and aloof candidates who thought that policy arguments were forms of persuasion.

The second conclusion was that the moral domain varies across cultures. Turiel's description of morality as being about justice, rights, and human welfare worked perfectly for the college students I interviewed at Penn, but it simply did not capture the moral concerns of the less elite groups—the working-class people in both countries who were more likely to justify their judgments with talk about respect, duty, and family roles. ("Your dog is family, and you just don't eat family.") From this study I concluded that the anthropologist Richard Shweder was probably right in a 1987 critique of Turiel in which he claimed that the moral domain (not just specific rules) varies by culture. Drawing on Shweder's ideas, I would say that the second rule of moral psychology is that morality is not just about how we treat each other (as most liberals think); it is also about binding groups together, supporting essential institutions, and living in a sanctified and noble way.

On Turiel's definition of morality ("justice, rights, and welfare"), Christian and Hindu communities don't look good. They restrict people's rights (especially sexual rights), encourage hierarchy and conformity to gender roles, and make people spend extraordinary amounts of time in prayer and ritual practices that seem to have nothing to do with "real" morality. But isn't it unfair to impose on all cultures a definition of morality drawn from the European Enlightenment tradition? Might we do better with an approach that defines moral systems by what they do rather than by what they value?

Here's my alternative definition: morality is any system of interlocking values, practices, institutions, and psychological mechanisms that work together to suppress or regulate selfishness and make social life possible. It turns out that human societies have found several radically different approaches to suppressing selfishness, two of which are most relevant for understanding what Democrats don't understand about morality.

First, imagine society as a social contract invented for our mutual benefit. All individuals are equal, and all should be left as free as possible to move, develop talents, and form relationships as they please. The patron saint of a contractual society is John Stuart Mill, who wrote (in On Liberty) that "the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others." Mill's vision appeals to many liberals and libertarians; a Millian society at its best would be a peaceful, open, and creative place where diverse individuals respect each other's rights and band together voluntarily (as in Obama's calls for "unity") to help those in need or to change the laws for the common good.

Psychologists have done extensive research on the moral mechanisms that are presupposed in a Millian society, and there are two that appear to be partly innate. First, people in all cultures are emotionally responsive to suffering and harm, particularly violent harm, and so nearly all cultures have norms or laws to protect individuals and to encourage care for the most vulnerable. Second, people in all cultures are emotionally responsive to issues of fairness and reciprocity, which often expand into notions of rights and justice. Philosophical efforts to justify liberal democracies and egalitarian social contracts invariably rely heavily on intuitions about fairness and reciprocity.

But now imagine society not as an agreement among individuals but as something that emerged organically over time as people found ways of living together, binding themselves to each other, suppressing each other's selfishness, and punishing the deviants and free-riders who eternally threaten to undermine cooperative groups. The basic social unit is not the individual, it is the hierarchically structured family, which serves as a model for other institutions. Individuals in such societies are born into strong and constraining relationships that profoundly limit their autonomy. The patron saint of this more binding moral system is the sociologist Emile Durkheim, who warned of the dangers of anomie (normlessness), and wrote, in 1897, that "Man cannot become attached to higher aims and submit to a rule if he sees nothing above him to which he belongs. To free himself from all social pressure is to abandon himself and demoralize him." A Durkheimian society at its best would be a stable network composed of many nested and overlapping groups that socialize, reshape, and care for individuals who, if left to their own devices, would pursue shallow, carnal, and selfish pleasures. A Durkheimian society would value self-control over self-expression, duty over rights, and loyalty to one's groups over concerns for outgroups.

A Durkheimian ethos can't be supported by the two moral foundations that hold up a Millian society (harm/care and fairness/reciprocity). My recent research shows that social conservatives do indeed rely upon those two foundations, but they also value virtues related to three additional psychological systems: ingroup/loyalty (involving mechanisms that evolved during the long human history of tribalism), authority/respect (involving ancient primate mechanisms for managing social rank, tempered by the obligation of superiors to protect and provide for subordinates), and purity/sanctity (a relatively new part of the moral mind, related to the evolution of disgust, that makes us see carnality as degrading and renunciation as noble). These three systems support moralities that bind people into intensely interdependent groups that work together to reach common goals. Such moralities make it easier for individuals to forget themselves and coalesce temporarily into hives, a process that is thrilling, as anyone who has ever "lost" him or herself in a choir, protest march, or religious ritual can attest.

Religion and political leadership are so intertwined across eras and cultures because they are about the same thing: performing the miracle of converting unrelated individuals into a group. Durkheim long ago said that God is really society projected up into the heavens, a collective delusion that enables collectives to exist, suppress selfishness, and endure. The three Durkheimian foundations (ingroup, authority, and purity) play a crucial role in most religions. When they are banished entirely from political life, what remains is a nation of individuals striving to maximize utility while respecting the rules. What remains is a cold but fair social contract, which can easily degenerate into a nation of shoppers.