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Why we have moral rules but don't follow them

Friday, 17. February 2012 - 21:10

WHY do we sometimes wrestle with moral dilemmas? A twist on a classic psychology experiment suggests that our minds have two parallel moral systems, and they don't always agree. In the trolley experiment, participants are told that a runaway tram trolley could kill five people on the tracks. They must decide whether to divert it onto a second track with only one person on it. Almost everyone diverts it, sacrificing one to save five.
But if instead you have to push one person off a bridge onto the track to stop the trolley, most people demur. That suggests most of us have a strict rule against killing people directly, even for the greater good.

How are such rules formed? Although moral codes appear to rule out the act of killing in the bridge experiment, most moral behaviour in animals appears focused on outcomes - the death of an individual, say - rather than the act that brought it about. When an animal experiences harm to help a relative, evolutionary biologists view this as increasing the chances that copies of the animal's genes will survive. Many psychologists think that human moral rules are an extension of this "kin selection".

Robert Kurzban of the University of Pennsylvania in Philadelphia thinks there's more to it than that. His latest study suggests there are moral rules that arose independently of those shaped by kin selection.

Kurzban's team gave volunteers variations of the bridge scenario. Volunteers were asked what they would do and whether their actions were morally right. Eighty-five per cent of them said it would be morally wrong to push one person off to save five, whether these people are brothers or strangers, confirming the idea that there is a rule against killing.

However, despite thinking it wrong, 28 per cent said they would still push a stranger off to save five, while 47 per cent said they would push a brother off to save five brothers. "They're more likely to do this 'less moral' thing if it's to save a relative," Kurzban says, suggesting kin selection is at work as well as the basic "moral rule" against killing (Evolution and Human Behavior, DOI: 10.1016/j.evolhumbehav.2011.11.002).

The experiment shows we have at least two parallel systems for deciding right and wrong: one that says some actions, like killing, are bad, and another that tells us to protect kin. They can clash, so how is this helpful? Co-author Peter DeScioli of Brandeis University in Waltham, Massachusetts, says social cohesion demands we have rules, regardless of what they are, to help resolve disputes quickly and peacefully.

DeScioli says our rule-making system is arbitrary, producing the belief that masturbation is "bad", for instance. The good news is that such rules can be changed.

But some may be harder to change than others, says Fiery Cushman of Brown University in Providence, Rhode Island. He says our protectiveness towards relatives influences rule-making, otherwise there would not be universal injunctions against theft, rape and murder.

by Michael Marshall

Source: 
www.newscientist.com/
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moral dilemmas
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psychology
Robert Kurzban
two parallel moral systems