Thursday, May 21, 2015

Is Human Morality Human Nature?

It is becoming increasingly difficult to argue that human morality is entirely the product of culture.  Christopher Boehm presents a very strong case in his two books Hierarchy in the Forest and Moral Origins that morality emerged as a product of social selection.  Human groups imposed strong pressure on their individual members to suppress selfish and especially bullying behavior.  Over periods of evolutionary adaptation, individuals who better internalized the moral rules of their groups and groups that contained more honest cooperators were more successful than those that did not do so.  Frans de Waal and Michael Tomasello have shown that human morality builds on cooperative behaviors observed in other primates and the latter has shown that moral instincts emerge in children reliably at a young age. 
Those who hold that morality is entirely artificial, the product of learning and culture, haven’t yet given up the game.  Francisco J. Ayala contributes a chapter in a book he co-edited with Robert Arp (Contemporary Debates in Philosophy of Biology) that makes just that case.  Ayala argues that the capacity for ethics is indeed part of human nature.  It is grounded in three products of natural selection: the ability to anticipate the consequences of our actions; the ability to make value judgments, and the ability to choose between courses of action.  All moral norms are the consequence of the application of these basic human capacities to recurrent problems.  If some moral norms seem to be universal (e.g. return favors) that is only because the problems are universal.  All moral behaviors are, however, exaptations rather than adaptations: they emerge in the course of human evolution not because they were selected for but because they are secondary consequences of traits that were selected for. 
I have to say that this smacks of an almost Cartesian view of human beings.  Descartes famously believed that animals were mere biological machines, whereas human beings alone, having souls, possessed the metaphysical capacity for consciousness and freedom.  If Ayala is right, human beings alone achieved by hard work alone what the other social primates were granted by way of instincts: altruistic norms promoting cooperative behaviors. 
Whether such a dualism is tenable is not worth discussing.  I would point out here that it neglects the distinction between moral reasoning and moral emotions, about which we now know a lot.  Consider the two basic versions of the infamous trolley problem.  In the “trolley problem”, a trolley is headed toward a switch.  As the switch is set, the trolley will move onto a track and kill five innocent people.  If you throw the switch it will divert the trolley, saving those people.  However, it will kill one innocent person on the other track.  In the “footbridge problem,” you can save the five people only by pushing one innocent person off a bridge, thus stopping the trolley. 
I have frequently presented these two dilemmas to my philosophy classes and asked for a vote.  My results always conform more or less exactly to the general statistics.  Most of my students (but not all of them) throw the switch in the first case but refuse to push the fellow off in the second.  The most fascinating thing about these two scenarios is that the two popular results‑throw the switch but don’t push the fellow off the bridge‑can each be easily explained by two mutually exclusive theories of ethics.  Utilitarians (or consequentialists) argue that an action is just if it secures the most good for the most people.  Throwing the switch in the first case is an easy utilitarian calculus and most people make it.  Deontologists (or Kantians) argue that if something is wrong then you just shouldn’t do it, regardless of the consequences.  Most people confronted with the second scenario come to precisely that conclusion.  Yet the body count is the same in either case. 
The key to understanding why the jury splits here is to consider the roles of moral reasoning and moral emotions.  This has been done in a remarkably precise way by Joshua D. Greene et al. in “An fMRI Investigation of Emotional Engagement in Moral Judgment” (Science vol. 293 14 September 2001).  The result was that the two problems engage different parts of the brain.  The reason that people react different to footbridge problem than to the trolley problem is that the former engages moral emotions whereas the latter does not. 
Human beings are clearly capable of exercising abstract moral reasoning.  That’s a good thing.  It allows us to make impartial judgments and to arbitrate in controversies where we have no interests.  It makes it possible for us to respond with flexibility to unexpected circumstances.  It makes it possible to legislate.  If Ayala were right, that is all there is to morality. 
Of course, he is wrong.  We also have strong moral emotions that, when engaged, channel our moral reasoning and place limits on our choices.  That’s a good thing too.  In the absence of moral instincts we would not be impartial judges all the time.  We are also subject to selfish instincts and conflicts of interests.  Moral emotions make us better partners, friends, and citizens by making it uncomfortable for us to bend our moral reasoning to selfish ends.  It is difficult if not impossible to explain our moral emotions except as evolved dispositions in a social primate species. 


  1. What too many don't realize is that one can simultaneously have a universal moral system, common to all human beings (meaning they are part of human nature), and cultural variations of those morals. People today seem to only notice the variations, falsely concluding that there is no commonality. If one group's definition of murder differs from ours, that doesn't mean murder isn't universal -- the fact that there is a definition at all proves it is!

  2. Unfortunately, Troy, you have said nothing with which I disagree.

  3. Why doesn't the trolley problem evoke moral emotions? Since the sacrifice is the same in both cases, I would have expected it to be equally emotionally troubling in both. Is the idea of physical distance (provided by the lever) really significant enough to activate a different part of the brain?

  4. Yes, apparently. In some people, the two problems do feel the same. For most, however, changing the direction of the train feels different from pushing the guy off the footbridge. In all fairness, it's not merely the "distance". In the trolley problem, the death of the one innocent is a consequence of the act that saves the three. In the footbridge problem, you are using an innocent person as a train stop. For Kantians, using a person in such a way to achieve an end, however laudable, is fundamentally immoral. It does look like this distinction depends on different parts of the brain.

  5. This makes a great deal of sense. Thanks, Dr. Blanchard!