Is doing the right thing hard-wired?

What gives people the ability to tell right from wrong? Is the moral sense instilled in us by God? Is it inculcated through religious training? Or does moral judgment vary according to the culture in which we were raised?

In a talk April 26, psychology professor Marc Hauser argued that our moral sense is part of our evolutionary inheritance. Like the “language instinct” hypothesized by linguistic theorist Noam Chomsky, the capacity for moral judgment is a universal human trait, “relatively immune” to cultural differences. Hauser described it as a “cold calculus,” independent of emotion, whose workings are largely inaccessible to our conscious minds.

Hauser, whose most recent book is “Moral Minds: How Nature Designed Our Universal Sense of Right and Wrong” (2006), draws his conclusions from experiments with nonhuman primates as well the Internet-based “Moral Sense Test,” administered to 150,000 subjects in 120 countries.

Hauser said that a key ability in making moral judgments is being able to read beneath the surface when observing another creature’s actions. Experiments show that monkeys, apes, and other animals share this ability with humans.

Evolution selected for this trait, Hauser said, because being able to perceive another creature’s intentions conferred a survival benefit over animals that could only respond to consequences.

“You can imagine the evolution of morality as a series of steps leading to a moral system,” he said.

Another important building block in the evolution of a moral sense is cooperation, which takes three different forms in the animal world. The first is cooperation based on kinship. An animal that sacrifices to benefit its offspring, for example, helps to protect their shared genes. In the second type, both individuals receive some cost, but both benefit. Cooperative hunting behavior is an example of this type. The third and rarest type is reciprocity, where an individual gives something up with the expectation that it will receive benefit in the future. The Golden Rule, Hauser said, is a formulation in human terms of this adaptation.

Hauser cited experiments with cotton-top tamarins in which individuals learned to manipulate a tool to provide a monkey in an adjoining cage with food if they believed that the other monkey would return the favor.

These experiments set the stage for the next chapter in the story, the evolution of human morality. Here Hauser turned to the results of the Moral Sense Test, which tracks responses to a series of hypothetical moral dilemmas. These responses have proven to be remarkably consistent, regardless of age, gender, religion, or cultural background.

In one example, a runaway trolley is about to kill five people walking on the tracks. You can flip a switch that will send the trolley onto a sidetrack where it will kill only one person. Is it morally permissible to flip the switch?

In another example, you are asked whether it is permissible to kill one healthy person so that doctors can harvest his organs and transplant them into five sick persons who would otherwise die.

Despite the fact that in both examples one person is sacrificed to save five others, respondents had no trouble distinguishing between the two cases. In the first case, 90 percent said it was OK to divert the trolley and kill one to save five, but in the second case 97 percent answered that it would be wrong to sacrifice a healthy person to allow five sick ones to live. Most people find it difficult or impossible to give a coherent explanation of why the two examples call for such different responses.

According to Hauser, responses to the Moral Sense Test indicate the presence of a moral grammar that exists in all of us and that influences the way we make moral judgments. This moral grammar is based on three basic principles: the intention principle or the doctrine of double effect, first formulated by Thomas Aquinas, stating that it is permissible to harm someone for the greater good if that person is not treated as a means to an end; the action principle, which holds that actively causing harm is worse than causing harm through inaction; and the contact principle, that it is worse to cause harm by one’s own hand than to do so indirectly.

Contrary to the famous statement by the character Ivan in Dostoevsky’s “The Brothers Karamozov” — “If there is no God, then all is permitted,” Hauser found no difference in the way religious and nonreligious people responded to the test. Nor did he find differences between men and women, a conclusion that seems to contradict Carol Gilligan’s pioneering work “In a Different Voice,” which contends that girls and boys differ in the way they reach moral decisions.

Hauser points out, however, that the Moral Sense Test measures moral decision-making, not behavior.

“The fact that humans have done horrible things is undeniable. The universality is in the judging part, not in the doing part,” he said.

Where religion and culture do make a difference is in how people judge particular situations. For example, in a famous essay, “A Defense of Abortion,” moral philosopher Judith Jarvis Thomson presents a hypothetical situation in which a person wakes up in bed and finds he has had his circulatory system connected with that of a famous violinist. He is told that the two of them must remain connected for nine months or else the violinist will die. Is it permissible to unplug oneself from the violinist even though doing so would cause his death?

The vast majority of people asked this question say that it is permissible to unplug oneself, even though the difference between this situation and pregnancy is difficult to articulate.

“Religion gives you rules that don’t apply when they are removed from the specific situation,” Hauser said.