Morality is not just something that people learn, argues Yale psychologist Paul Bloom: It is something we are all born with. At birth, babies are endowed with compassion, with empathy, with the beginnings of a sense of fairness. It is from these beginnings, he argues in his new book Just Babies, that adults develop their sense of right and wrong, their desire to do good — and, at times, their capacity to do terrible things. Bloom answered questions recently from Mind Matters editor Gareth Cook.

What are the first signs of morality in babies?

The earliest signs are the glimmerings of empathy and compassion—pain at the pain of others, which you can see pretty soon after birth. Once they’re capable of coordinated movement, babies will often try to soothe others who are suffering, by patting and stroking.

The sort of research that I’ve been involved with personally, looking at the origins of moral judgment, is difficult to do with very young babies. But we have found that even 3-month-olds respond differently to a character who helps another than to a character who hinders another person. This finding hints that moral judgment might have very early developmental origins.

What is the strongest proof that morality has a genetic component, that two people may have differing moral views because of their genes?

There have been the usual sorts of behavioral genetics studies—adopted children, twins separated at birth, that sort of thing—that find evidence for heritability in capacities such as empathy, which is plainly related to morality.

But I think the strongest evidence that morality has a genetic component has little to do with human differences, and everything to do with human universals. Every normal person has a sense of right and wrong, some appreciation of justice and fairness, some gut feelings that are triggered by kindness and cruelty. I like how Thomas Jefferson put it—the moral sense is “as much a part of man as his leg or arm.”

What would you say are the moral principles which young children share?

A list would include: An understanding that helping is morally good, and that harming, hindering, or otherwise thwarting the goals of another person is morally bad. A rudimentary sense of justice—an understanding that good guys should be rewarded and bad guys should be punished. An initial sense of fairness—in particular, that there should be an equal division of resources. And alongside these principles are moral emotions, including empathy, compassion, guilt, shame, and righteous anger.

Can you give an example of a moral principle from childhood that tends to change as we grow older?

An understanding of fairness goes through considerable development as someone gets older. For young children, fairness pretty much reduces to equality—everyone gets the same. It’s only with development that we come to an appreciation of the complex ways in which fairness might diverge from equality, such as when one person deserves more (by working harder, perhaps) or is in greater need or has been short-changed in the past. In fact, even adults differ in our intuitions about what is, and what is not, fair. This is a domain in which there is a fascinating interplay between innate capacities, cultural learning, and the individual exercise of reason.

Are there ways that the moral emotions you mentioned — like “righteous anger” — lead to behavior that we would call “immoral”?

Absolutely. Our emotions have evolved for simpler times. They are not well calibrated for the modern world, where we are surrounded by countless strangers and have access to cars, guns, and the Internet. It makes sense to be outraged when you are deceived by a friend or when someone you love is wronged. This can be a moral response. But it is irrational—and often immoral—when the same anger is acted upon towards someone who cuts you off on the highway. Worse, righteous anger can provoke international confrontations that can lead to the death of millions. Anger is one thing when you are armed with your fists and a stick; quite another when you have an army and nuclear weapons.

It’s not just anger, though. All of the moral emotions can have disastrous effects. As I argue in a recent New Yorker article, I think this is true even for empathy—the capacity to put yourself in someone else’s shoes, to feel their pleasure and their pain. When it comes to personal relationships, empathy can be a good thing—I wouldn’t want a parent, a child, or a spouse who lacked empathy. But, just as with anger, empathy doesn’t scale. It is because of our empathetic responses that we care more about a little girl stuck in a well than about billions being affected in the future by climate change. The girl elicits empathy; statistical future harms do not. To the extent that we can recognize, and act upon, serious threats that don’t have identifiable victims, we are relying on rational deliberation, not gut responses.

How has learning about the origins of morality changed how you view the moral reasoning of adults?

There are two discoveries that I discuss in Just Babies that influence how I think about adult moral reasoning. The first is that there are hard-wired moral universals. To an important extent, all people have the same morality; the differences that we see—however important they are to our everyday lives—are variations on a theme. This universality provides some reason for optimism. It suggests that if we look hard enough, we can find common ground with any other neurologically normal human.

The second discovery is the importance of reason. Prominent writers and intellectuals like David Brooks, Malcolm Gladwell, and Jonathan Haidt have championed the view that, as David Hume famously put it, we are slaves of the passions. Our moral judgments and moral actions are driven mostly by gut feelings—rational thought has little to do with it. I find this a grim view of human nature, but if it were true, we should buck up and learn to live with it.

But I argue in Just Babies that it isn’t true. It is refuted by everyday experience, by history, and by the science of developmental psychology. It turns out instead that the right theory of our moral lives has two parts. It starts with what we are born with, and this is surprisingly rich: babies are moral animals. But we are more than just babies. A critical part of our morality—so much of what makes us human—emerges over the course of human history and individual development. It is the product of our compassion, our imagination, and our magnificent capacity for reason.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist and regular contributor to NewYorker.com. Gareth is also the series editor of Best American Infographics, and can be reached at garethideas AT gmail.com or Twitter @garethideas.