Lessons in moral science

Imagine that you are standing next to a railway track and you see a runaway trolley, with nobody on board, heading towards a group of five people down the track.

The only way to save these people is to throw a switch that will divert the train to another track. This will save the five, but will kill another person standing on the second track.

Now imagine the same runaway trolley and the same five people, but this time you are standing on a bridge above the track, next to a very large stranger.

The only way to stop the trolley is to shove the man off the bridge and into the trolley's path, killing him but saving the five. (It won't help to jump yourself; you are too small to stop the trolley.)

What is interesting is that both situations present the option of saving five by killing one, but most people respond to them differently. Most believe that you would be right to throw the switch but wrong to push the man. But why do we think this? And are we right to do so?

It used to be that the only people who had even heard of such dilemmas were professional philosophers. But now it seems everyone is doing trolleyology.

Neuroscientists have used brain-imaging techniques to see which parts of the brain light up when people reason about such problems and psychologists have conducted web-based surveys to monitor the intuitions of hundreds of thousands of people from different countries and cultures.

More generally, scientists around the world are exploring how we reason about right and wrong, looking not only at the usual pool of undergraduate volunteers but also at specialised populations such as hunter-gatherers, children and psychopaths.

And there is a rich body of theoretical work in behavioural economics and evolutionary psychology that attempts to explore the rationale behind our moral thoughts and feelings.

Unwise isolation

In the short and brilliant Experiments in Ethics, Princeton philosopher Kwame Anthony Appiah discusses this research and what it means for ethics.

He starts by pointing out that philosophy has almost always had an experimental side. David Hume, for instance, was adamant that moral philosophy had to be grounded in facts about human nature, in psychology and history.

Even Kant mixed his moral philosophy with practical observations and suggestions, on topics including child raising (“games with balls are among the best for children''). The idea of philosophy as an isolated discipline, Appiah argues, is a relatively newfangled idea, and not a good one.

Many philosophers, for example, argue that doing good, and living a good life, consists of possessing virtues such as honesty and kindness, and that a good society should aspire to cultivate these virtues in its citizens.

But a large body of evidence suggests that these enduring character traits, to the extent that they even exist, may not play much of a role in moral action. Instead, our behaviour is determined to a surprising extent by the situation.

Appiah says we are usually not conscious that this is happening. If you are standing outside a bakery with the smell of fresh bread in the air, one study showed, you are more likely to help a stranger than if you are standing outside a “neutral-smelling dry goods store''.

If you read sentences with words such as “honour'' and “respect'' you tend to be more polite, minutes later, than if you had read sentences with words such as “obnoxious'' and “bluntly''.

And then there are well-known demonstrations, such as the obedience experiments of Stanley Milgram, that you can get an average person to do terrible things by configuring the situation in a certain way.

This has implications for how we think of moral responsibility. Social psychologists argue, for instance, that the atrocities of wartime are usually not the acts of terrible people but are instead what normal people do when put in a terrible situation.

Talking about the genocide of the Tutsis in Rwanda in 1994, Appiah suggests that “if you or I had been planted on this earth as Hutus at that time and place, we too would probably have been participants''.

While I think this point is often somewhat overstated, Appiah is probably right when he concludes that we should place less emphasis on “character education'' and focus more on trying to establish situations in which people's better selves can flourish.

Trusting the gut

Appiah believes that experimental research has an even deeper connection to morality. To some extent, we have to trust our gut feelings when determining what is right and wrong.

But sometimes our feelings conflict: A minority feel that it is perfectly fine, for instance, to push the fat man into the path of the trolley. We can feel superior to our ancestors who sincerely believed that slavery was good and interracial marriage evil, but surely our grandchildren are going to feel the same way about some of our views.

Experimental psychology doesn't answer this question, but it might help. Appiah reviews the literature showing how our judgments can be affected by factors that, when we think about them, we can agree are irrelevant.

Research by the psychologist Jonathan Haidt, for instance, suggests that disgust is a powerful trigger for moral condemnation — being grossed out makes us mean — even if we are disgusted for reasons that have nothing to do with the person or act we are judging.

This is useful to know, particularly given the role disgust plays in contemporary political rhetoric.

I wish every philosopher wrote like Appiah. Experiments in Ethics is accessible and clear (and often very funny), and Appiah is generous when it comes to discussing the work of those he disagrees with.

The trolley literature “makes the Talmud look like Cliffs Notes'' even as its complexity fails, he argues, to capture the richness of morality in our lives. Real problems don't come in the form of SAT questions, and being a good person requires figuring out for yourself just what the options are.

This is bad news for those who hope for a simple and elegant account of moral life, which includes many of us engaged in experimental philosophy. But it fits with Appiah's worldview.

Near the end of the book, he says that when he tells a stranger that he is a philosopher, he often gets the question: “What's your philosophy?'' He answers: “My philosophy is that everything is more complicated than you thought.''

Paul Bloom, a professor of psychology at Yale, is the author of Descartes' Baby: How the Science of Child Development Explains What Makes Us Human. He is at present writing a book about pleasure.