Moral Tribes by Joshua Greene – review

http://www.theguardian.com/books/2014/jan/13/moral-tribes-joshua-greene-review

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You are standing on a bridge over a railway track when you observe a runaway truck on course to kill five railway workers. Right next to you stands a large man. The only way to save the five men is to push your hapless neighbour off the footbridge and on to the track below. The man will die but his bulk will stop the truck. (You are too puny to stop it if you jump in front of it yourself.)

Now a variation: a runaway truck is heading for the same five men, who will be killed if nothing is done. You can save them by operating a switch that will divert the truck to a sidetrack. However, on the sidetrack there is a single workman, who will be killed if you pull the switch.

This grisly thought experiment is known as "the trolley problem" (in the US the runaway truck is called a trolley), and if you are like most of the world you'll decide that while it would be wrong to push the fat man off the footbridge, it would be acceptable to operate the switch, despite the fact that the number of lives lost and saved are identical.

This fairly hoary ethical dilemma lies at the heart of Moral Tribes by Joshua Greene, director of the Moral Cognition lab at Harvard, and a leading light in the burgeoning field of moral psychology.

The evidence collected by Greene and others suggests that we have strong disinclinations to perform certain acts (murdering the fat man), even though they serve the greater good, but not others (pulling the switch) that have the same outcome.

What Greene and his team have added to this unnerving moral conundrum is the systematic use of multiple brain images that demonstrate that when people contemplate sacrificing the fat man there is increased activity in the ventromedial prefrontal cortex, a part of the brain associated with emotion, whereas consideration of operating the switch promotes increased activity in the dorsolateral prefrontal cortex, the part of the brain associated with reasoning. People with damage to the ventromedial prefrontal cortex, who lack normal emotions, were five times more likely to approve of pushing the fat man off the bridge.

Greene began his career as a philosopher so is well placed to consider the question of ethics from a theoretical as well as an empirical perspective. There have been a number of books recently that consider the biological roots of moral sense (Paul Bloom's Just Babies is the most recent example). But while Greene's research suggests, in accordance with Bloom, that the rudiments of morality are indeed innate, it also demonstrates, through such experiments as the trolley problem, that our moral responses rest on a wobbly intuitive base – a gut feeling that may not produce the best general outcome.

In a nutshell, his research reveals two basic settings in our brain which – using a camera as an analogy – he terms automatic and manual. (He acknowledges a debt here to Daniel Kahneman's Thinking, Fast and Slow, in my view an even more original book than either Bloom's or Greene's.) The automatic setting produces the instinctive or emotional response while the manual allows for consideration and reason.

Greene uses a parable to illustrate what he calls "commonsense morality" – in his view "the central tragedy of modern life, the deeper tragedy behind the moral problems that divide us". The parable is of tribes with a common resource that can be depleted or sustained according to the rules that determine its usage and the degree of willingness to sacrifice self-interest for the collective good. It runs as a theme throughout the book to highlight the mounting global danger of humankind's apparently inbuilt parochialism.

According to Greene, our moral brain is programmed to operate on an emotional basis to serve a select community or tribe (the physical proximity of the fat man and the relative distance of the solitary worker may explain our disinclination to sacrifice one and not the other). But what functions to promote harmony within a group becomes the source of antagonism when encountering other groups who give different moral weight to what determines the good.

Evolution, Greene contends, has prepared us for moral behaviour within our own tribe (us) but not with other tribes (them), and this gives rise to the countless conflicts and atrocities that beset the world: racism, antisemitism, ethnic cleansing, holy wars, genocide and – less dramatically if no less deleterious to global harmony – sexism, ageism, homophobia, class war and the problems of multiculturalism.

Greene's radical contention (pretty much a plea) is that the world will only be saved if we learn to transcend our intuitive responses in favour of what he wants to call "deep pragmatism", which is in fact a refined form of utilitarianism, the philosophy of the greatest good for the greatest number. This is only achievable where reason trumps emotion. It is a bold idea but my gut feeling is that it is inoperable because it leaves unanswered the problem of who shall say what is the general "good".

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