The Problem with Moral Psychology

What science says about moral truths and romancing your sibling

Every year, I (Kurt) teach an undergraduate psychology course called the Science of Moral Understanding, for which Sam is a teaching assistant. The goal of the course is to understand where our moral values come from, so that we can better understand ourselves and those who disagree with us. We begin with a thought experiment from a classic moral psychology paper by Jon Haidt:

“Julie and Mark, who are brother and sister, are traveling together in France. They are both on summer vacation from college. One night they are staying alone in a cabin near the beach. They decide that it would be interesting and fun if they tried making love. At the very least it would be a new experience for each of them. Julie was already taking birth control pills, but Mark uses a condom too, just to be safe. They both enjoy it, but they decide not to do it again. They keep that night as a special secret between them, which makes them feel even closer to each other. So what do you think about this? Was it wrong for them to have sex?”  

The students, after some laughter and nervous glances between friends, muster the confidence to offer their opinions. Some say, “It’s fine, I guess, because no one was harmed,” but most others argue “It’s just wrong! They’re brother and sister!” We discuss why someone might answer one way or the other, but they eventually want to know the true answer to this question—is what Mark and Julie did objectively wrong? 

This is where we shrug. A key point of the course is that there might not be objective answers to questions of morality. Our moral judgments—or intuitions—evolved to help keep us safe and our social groups stable, often leading to bizarre, short-sighted, and contradictory beliefs. The burning of witches, human sacrifices, and even infanticide have historically been upheld as “moral” when they seem to safeguard one’s own tribe.  

Moral psychologists study these beliefs, and many of us agree that once we’ve mapped out people’s morals and the psychological processes that cause them, there might be nothing else to say about the objective moral goodness of any act. At the very least, if there is a true moral order to the universe, our moral judgments certainly don’t reveal it. Our feelings about right and wrong might be just that—feelings. 

When we tell the students that their revulsion at consensual incest might not reveal any objective wrongness of Mark and Julie’s romantic getaway, they are often incredulous and more than a bit disgusted. They also seem suspicious of us, the laissez-faire scientists telling them that the morality of sibling incest “just depends on who you ask.”  

Does thinking of morality as relative make us monsters? Without a true North to our moral compass, are we likely murderers? How could moral psychologists—or any moral relativists—be trusted with children!? 

We don’t think that moral psychologists are evil (though our field’s fascination with consensual incest is admittedly strange). In fact, we think that appreciating that morality is relative is useful. Only when we recognize the subjectivity of our own moral judgments can we understand the morals of our opponents—and stop viewing them as objectively evil. 

In this post we’ll explain why human morality falls far short of objectivity, and why this idea rubs people the wrong way. All of us—even moral psychologists who argue for moral relativism—tend to feel that the answers to morality are etched in stone. 

Do Moral Philosophers Have the Answers? 

The potential existence of objective morality—of true answers to questions of right and wrong—is alluring to everyone, but some people have made finding moral truths their full-time job. Moral philosophers use logic and reason to try to figure out what makes something morally good. Unfortunately, attempts to define moral goodness from a set of rules often result in evil. 

Consider Immanuel Kant, one of the world’s most famous philosophers. He argued that you should only consider an act morally good if you would want anyone to do it, in any situation (he called this idea the “categorical imperative”). When we apply Kant’s rule, we can say that lying is objectively morally wrong because there are many cases where we wouldn’t want someone to lie, like lying to your spouse about infidelity or a doctor misinforming a patient about a diagnosis.  

Fair enough, but thinking of lying as objectively wrong leads to some bad consequences. If your friend asks you whether you like their new haircut, and you think it looks like roadkill, you have to say “your haircut looks like roadkill.” They will be devastated, but tough cookies—you’re just being super ethical.  

But is being cruel to a friend really ethical when a white lie would have saved their feelings? Kant doubled down—he thought it was unethical to lie to someone even if that lie could save the lives of an innocent family. If, during World War 2, the Gestapo came to your door and asked if you might have seen any Jewish families hiding, and you knew there was a Jewish family hiding in a nearby barn, Kant’s ethics require you to volunteer that information, because truth is (always) the (objectively) best policy.  

Any ethical rule that makes white lies more immoral than being complicit in genocide seems strange, and many people are rightly suspicious of Kant’s assertions because they conflict with our moral intuitions. We just feel that lying is not as bad as causing an innocent family to get murdered, and we prioritize those feelings over any objective rule. This seems to prove that in practice, people are moral relativists: our moral judgments are based less on principled rules and more on gut feelings. 

These gut feelings are fickle and swayed by things that everyone—especially philosophers—would consider irrelevant to morality. For example, a classic study analyzed 506 court cases and found that the more baby-faced the plaintiffs were (having round faces with big eyes, a narrow chin and a small nose), the more likely judges were to rule in their favor. Objectively speaking, whether someone has a cute face should not influence a court decision, but even judges—who are striving for moral truth—couldn’t resist the evolved human tendency to think “aww” when confronted with a baby-like face.  

That we can’t put our trust in the ethical absolutes of philosophers argues against objective morality, at least from philosophy. But there’s a problem with philosophers: they’re only human. For millennia, people have put their faith in another ultimate source of morality: God. But is religious morality really so objective? 

Morality from God? 

Many religious traditions believe that objective morality comes from an all-knowing, all-powerful, and all-loving God. For example, Christianity teaches that the ten commandments were revealed to Moses by God on Mount Sinai, giving us rules like “thou shalt not murder” and “thou shalt not steal.” There is no denying that these rules, as well as allegories from the Bible and other religious texts, provide some ethical guidance to billions around the world. But despite how clear cut these rules may seem, religious morality—at least in practice—is far from objective. 

One problem is that religious texts require human interpretation, which is inherently subjective. People must make inferences about the meaning of ambiguous rules—does “do not get drunk on wine, which leads to debauchery” (Ephesians 5:18-29) prohibit drinking altogether, or just drinking wine?—and determine how ancient rules apply to modern questions—how do the Psalms apply to behavior on social media? 

Subjectivity also seeps in when people pick which of God’s lessons might be most appropriate for a situation. If someone bullies you or your friends, should you turn the other cheek (Matthew 5:39) and avoid retaliation (Romans 12:17-19), or should you seek to stand up to injustice on behalf of all those who are needy (Proverbs 31:8-9)? 

Even if God really does have answers to these thorny moral questions, His mind is ultimately unknowable, which gives people another chance to inject their own subjective feelings into questions of objective morality. This explains why, even within congregations, there is heated disagreement about whether religion permits abortion, same-sex marriage, and related behaviors. It also explains why, when people think about the divine mind, they tend to just view God in their own image, assuming that His moral judgments exactly match their own. 

One study by Nick Epley and his colleagues demonstrated this moral “egocentrism” (anchoring on yourself) by asking religious people for their opinions on various ethical issues including same-sex marriage, the death penalty, and marijuana. Next, these researchers asked participants to guess how God feels about those issues. They found that people’s perceptions of God’s morals depended on their own personal beliefs. Christians who were staunchly anti-marijuana were convinced that God was too, but Christians who were down with getting stoned were more likely to think that God supports legalizing marijuana. 

Of course, one explanation of these results could be that the participants really were in touch with God’s morals and used them as a guide for their own beliefs. To rule this possibility out, the researchers ran a second experiment where they exposed people to persuasive arguments either for or against another moral issue: affirmative action. They found that people who read pro-affirmative action arguments became more favorable towards the policy, but they also said that God did too (see Figure 1). In other words, people based their perceptions of God’s “objective” morals on their own gut feelings, which were flimsy enough to be swayed by a simple argument. 

Figure 1. Participants who read arguments in favor of affirmative action (“Pro-Policy” condition) think that God is also more favorable toward affirmative action. From Epley et al., 2009. 

You can also see evidence for moral relativism in the change of official religious stances over time. For example, until the mid-1970s, many white evangelical Americans were not opposed to abortion. In 1968, the prominent evangelical theologian Bruce Waltke argued for the ethicality of abortion in Christianity Today: “God does not regard the fetus as a soul, no matter how far gestation has progressed. The Law plainly exacts: ‘If a man kills any human life he will be put to death’ (Lev. 24:17). But according to Exodus 21:22–24, the destruction of the fetus is not a capital offense… Clearly, then, in contrast to the mother, the fetus is not reckoned as a soul.”  

As Dartmouth religion professor Randall Balmer reports in Politico, staunch anti-abortion attitudes among evangelicals only emerged in the late 70s, when a political rallying cry by rightwing religious leaders mobilized evangelical conservatives to the polls.  

Our aim here is not to be critical of religious foundations of morality, but only to show that no matter where you get your morals—from faith or secular principles—your values are less objective than you might believe. This can be a scary realization, because the alternative—moral relativism—seems to provide a slippery slope. If morality is a product of human feelings and not God’s eternal law then—people wonder—what’s to stop us from committing abuse, adultery, or even genocide? There seems to be something deeply suspicious about moral relativism and those who endorse it. 

The Mistrust and Redemption of Moral Relativists 

Many people believe that without an objective moral authority to guide our behavior, we can't be moral at all.  

According to a 2014 Pew poll, 53% of Americans agree that it’s “necessary to believe in God to be moral.” This explains why, according to a 2020 poll, 40% of Americans would not vote for a presidential candidate who is openly atheist, even if they agreed with their politics. The prospect of moral relativism seems to destroy the very foundations of right and wrong, an idea captured nicely by Dostoevsky’s famous line “If God does not exist, then everything is permitted.” 

The psychologist Will Gervais has spent much of his career showing that people intuitively agree with this trope, and consequently mistrust moral relativists—especially atheists, who disavow God’s moral law. In one experiment, Gervais and his colleagues presented participants with a description of an extremely evil person: “a man who tortures animals as a child and then as an adult exhibits escalating violence culminating with the murder and mutilation of five homeless people.” Gervais then asked participants how likely this person was to be atheist versus religious. As Figure 2 shows, people across the board believed that the serial killer was a probable atheist. This prejudice ran so deep that it was even present (though less so) in more secular countries like New Zealand and the Netherlands.  

Figure 2. Even in secular countries, people intuitively associate serial killers with atheism. From Gervais et al., 2017. 

Is the mistrust of moral relativists fair? If so, then we should be very concerned, because countries across the world are becoming increasingly secular. Should we brace ourselves for a global spike in serial killers? 

Fortunately, acknowledging the subjectivity of morality doesn’t make us evil. Our moral intuitions, though context-dependent and subjective, run deep in our minds and usually serve as powerful checks to our most anti-social impulses. There’s a reason that serial killers evoke so much fascination: they are extremely rare and extremely different from the average human. For the rest of us, our moral intuitions—and especially the powerful desire to be seen as good by others—typically keep away the darker sides of human nature.

One of our lab’s former postdocs, Andy Vonasch, published a paper called “Death Before Dishonor” that reveals just how far people will go to preserve their reputation as a good person. Many of his participants reported that they would rather incur terrible consequences, like jail time, amputation, and even death, than have others think they are guilty of something awful, like being a Nazi or a child molester.  

Andy was also able to convince a sizeable portion of college students (30%) to actually stick their hand into a bucket of live worms (see Figure 3) to prevent the researchers from sending an all-school email telling everyone that they were racist. Even if our answers to questions of right or wrong depend upon our context and social group, at least people care deeply about being seen as moral by that social group—and this keeps us acting ethically even in the absence of moral absolutes. 

Figure 3. 30% of college students chose to stick their hand in this bucket of worms to avoid seeming racist. From Vonasch et al., 2017. 

It’s fortunate that a morality based on evolved social intuitions doesn’t make us serial killers, because we can have some peace of mind at night. It’s also fortunate because acknowledging the possibility of moral relativism—far from making us evil—can actually make us more moral and understanding people.  

From Right and Wrong to Understanding 

Recognizing the subjectivity of our own morals is a first step to understanding people with different moral beliefs. Our moral minds dictate our subjective perception of morality, and they also compel us to see those subjective perceptions as objective—and to attack and dehumanize the "other side". But if we had been born into a different group, with different beliefs or religious views, we’d probably feel just as strongly that those beliefs were objectively true.  

The obvious power of our social groups to shape morality is why so many moral psychologists work to bridge moral divides. When you are confronted every day with the fickleness of people’s ethical intuitions, it’s hard to believe that morality is objective. Of course, even moral psychologists feel the truth of their convictions burning in their heart like an eternal flame, and still have ethical causes that they care deeply about. Acknowledging the subjectivity of morality doesn’t require that we drop our convictions but rather gives us some humility about where they come from. 

When we realize that our judgments of moral issues—like two siblings going on a romantic getaway—are often a matter of perception, it reminds us that people who disagree with us on bigger moral issues can still be decent, reasonable people. We all see our positions on abortion or immigration as self-evident facts, but these feelings grow out of a mind that evolved primarily for getting along in tribes, not for discovering the ultimate moral truth of the universe. 

Believing that morality is relative doesn't make you a monster. Instead, it makes you less likely to believe that other people are monstrous—and this is a crucial step to moral understanding.