The Scientific Study of Moral Emotion and Moral Reason in the Brain: Joshua Greene's Dual Process Theory

For thousands of years, political philosophers have debated the role of emotion and reason in moral judgment.  We can now study this question scientifically through evolutionary theory and neuroscience.  If the brain is a product of Darwinian evolution, then we can explain how the brain supports moral judgment as shaped by evolutionary selection.  We can also study the activity of the brain as engaged in moral judgments to identify the interaction between the more rational capacities and the more emotional capacities.  One way to do this is to use functional MRI brain scanning while people are thinking about moral dilemmas presented to them.  Some of this research uses the trolley problems developed by philosophers as thought experiments in experimental neuroscientific studies.  For me, this shows how we can turn political philosophy into an empirical science.  So, for example, I think we can see much of this scientific research as supporting the moral psychology of David Hume and Adam Smith.

One of the leaders in this research is Joshua Greene, who directs the Moral Cognition Lab at Harvard, and who has recently published a book surveying his work--Moral Tribes: Emotion, Reason, and the Gap Between Us and Them (Penguin Press, 2013).  In explaining moral philosophy as rooted in an evolutionary moral psychology, Greene shares a lot in common with Jonathan Haidt, who has been the subject of previous posts here and here.  But they disagree about exactly how emotion and reason are related in moral experience.  Haidt thinks Hume was right about reason being the slave of the passions.  As Haidt suggested in the title of one of his articles, the emotional dog wags his rational tail.  On the contrary, Greene argues, our capacity for rational deliberation can sometimes set aside what our moral emotions tell us, and this capacity for reasoning can lead us to embrace the principles of utilitarianism as the best moral philosophy, even though utilitarian thinking sometimes requires the denial of our emotional moral intuitions.  He believes that we can see this in the responses of the brain to trolley problems--and particularly in comparing our responses to the Switch Case and the Footbridge Case.

I agree that Greene's research illuminates the evolutionary and neural grounds of moral psychology.  But his argument for utilitarianism (of the sort developed by Peter Singer) seems incoherent to me.  I agree that we are partial utilitarians, because we all want to be happy, and we don't want to be miserable.  But we are not pure utilitarians of the Singer kind, because while we care for the happiness of all human beings to some degree, we care more for the happiness of ourselves and those close to us.  Pure utilitarianism in which we would maximize happiness impartially, so that no one's happiness would be any more important than anyone else's, is inhuman in its denial of our evolved human nature.  Oddly, Greene admits this when he says that utilitarians must be hypocrites, because their human nature forces them to love themselves and love their own more than strangers.  That's what I mean by incoherence.

I also disagree with Greene's claim that his research supports left liberalism as the best way to overcome the conflicts between moral tribes.  As he himself admits, libertarians are "the least tribal people of all" (341).  But he fails to see how the libertarian appeal to the individual liberty to pursue one's happiness provides the broadest foundation for moral tribes to live together in peace.  I have made a similar argument in my posts on Haidt.

I'll elaborate these points in subsequent posts.