Neuroscience and Ethics

Neuroscience can explain some things, but not others. Among its more conspicuous limitations is its inability to explain moral judgment.

In effect, it’s an old story, dating to David Hume. Every philosopher knows Hume’s argument: science can describe what is; ethics tells us what we should do.

Science can tell you what happens when you shoot a bullet into the wall. It can tell you what happens when you shoot a bullet into someone’s head. It does not tell you whether you should do the one or the other.

If you are thinking that it is wrong to shoot people in the head, what should you do when someone is coming at you with an axe?

Recently, philosopher Thomas Nagel raised these issues, and many more, in a review of Joshua Greene’s new book: Moral Tribes: Emotion, Reason, and the Gap between Us and Them.

Nagel is an eminent philosopher; he is emeritus at New York University. Greene is an associate professor of psychology at Harvard.

One is tempted to call it a clash of the academic titans.

It begins with an analysis of what is called the footbridge or trolley dilemma:

 The footbridge dilemma: A runaway trolley is headed for five railway workmen who will be killed if it proceeds on its present course. You are standing on a footbridge spanning the tracks, in between the oncoming trolley and the five people. Standing next to you is a 300-pound man. The only way to save the five people is to push him off the footbridge and onto the tracks below. The man will die as a result, but his body will stop the trolley. (You are only half his size and would not stop the trolley if you yourself jumped in front of it.)

 The switch dilemma: A runaway trolley is headed for five workmen who will be killed if nothing is done. You can save these five people by hitting a switch that will turn the trolley onto a sidetrack. Unfortunately there is a single workman on the sidetrack who will be killed if you hit the switch.

Research has shown that more people will hit the switch than will throw the 300-pound man on the tracks. Apparently, this demonstrates that the brain indulges in two kinds of moral reasoning, deriving from different neural systems.

Sometimes we use reason; sometimes we act out of emotion. Such is the conclusion that neuroscientists have reached.

We ought to recognize that these situations are both fictions. How does your response change when the 300 pound man is a stranger and the people on the track are members of your family? Or, vice versa.

Shouldn’t you consider the consequences you will suffer if you allow your five brothers to be hit be a trolley? How are you going to explain to their families that you could have prevented it but didn't? Are you going to say that you were following a principle you learned in a college course?

And don’t the two tasks entail completely different levels of risk? If you yourself are considerably smaller than the 300-pound man, it might not be very easy to push him onto the tracks? If he is an offensive lineman on a professional football team he might easily respond to your threat by throwing you on the track. Then, six people will die.

Obviously, hitting a switch does not put you at any risk, though questions of criminal liability will surely enter into your calculations.

Apparently, Greene believes that there is something wrong in the way people react to the footbridge problem. By his lights and by his utilitarian calculation we should in all cases opt for saving the most lives. That is, we should not even calculate at the minimal level that the initial problem suggests. We should not make risk assessments and should not, ideally, privilege friends and family over strangers.

How long do you think the human species would have survived if everyone had thought in those terms?

Nagel responds by noting that human ethics promotes cooperation within groups but does not promote cooperation with outsiders. Ethics is based on a distinction between friend and foe or friend and stranger.

Apparently, this chagrins thinkers like Greene who believe that since all human beings belong to one species they are equal in the most relevant respects and should be treated as such.

If science, Greene seems to be saying, does not distinguish between different members of the same species, we should not do so either. He seems to be aiming at a utopia where everyone gets along, where there are no insider and outsiders, where there are no friends and enemies.

It is worth underscoring that such a world is a pure fiction. To denounce human beings for not living according to a fiction is to take leave of reality.

It is irrational to do so, Nagel suggests, in the name of science.

Nagel summarizes Greene’s argument:

Greene calls this problem the “tragedy of commonsense morality.” In a nutshell, it is the tragedy that moralities that help members of particular communities to cooperate peacefully do not foster a comparable harmony among members of different communities.

Morality evolved to enable cooperation, but this conclusion comes with an important caveat. Biologically speaking, humans were designed for cooperation, but only with some people. Our moral brains evolved for cooperation within groups, and perhaps only within the context of personal relationships. Our moral brains did not evolve for cooperation between groups(at least not all groups).... As with the evolution of faster carnivores, competition is essential for the evolution of cooperation….

We feel obligations to fellow members of our community but not to outsiders. So the solution to the tragedy of the commons has generated a new tragedy, which we can see wherever the values and the interests of different communities conflict, not only on an international scale but also more locally, within pluralistic societies that contain multiple moral communities.

To solve this problem Greene thinks we need what he calls a “metamorality,” based on a common currency of value that all human beings can acknowledge, even if it conflicts with some of the promptings of the intuitive moralities of common sense.

Nagel explains that Greene’s argument derives from utilitarian morality—the greatest good for the greatest number, regardless of who they are and what my relationship to them is.

In Nagel’s words:

Utilitarianism, as propounded by Bentham and Mill, is the principle that we should aim to maximize happiness impartially, and it conflicts with the instinctive commonsense morality of individual rights, and special heightened obligations to those to whom one is related by blood or community. Those intuitive values have their uses as rough guides to action in many ordinary circumstances, but they cannot, in Greene’s view, provide the basis for universally valid standards of conduct. 

The basic point for Greene’s purposes is that we have strong moral reactions against certain actions that cause harm but serve the greater good on balance, but not to other actions that produce the same balance of good and harm.

Utilitarianism, he believes, allows us to transcend our evolutionary heritage. The question then is whether he offers a coherent account of how and why we should give it this authority.

Greene is asking us to overcome our human nature, to ignore traditional ethics, and to write ourselves out of whatever groups we belong to.

If, as most people accept, humans are social beings, they all belong to one or another group. But, it means nothing to belong to a group if everyone belongs to the group and no one belongs to another group. Even lions have prides.

Moreover, if the bottom line sees us all as members of the species, our membership and our status do not depend on how we behave. If biology places you in the species, nothing you can do can remove you from it.

Call it human nature if you like, but the supposedly scientific approach is really a disguised form of heavy idealism, the kind that dislikes human beings as they are and rejects their way of reasoning morally. Greene wants us to overcome our humanity and our moral nature.

Nagel writes:

This implies something that is clearly not a fact of empirical psychology: namely, that there are values by which we should “ideally” govern our lives, and that they are captured by the utilitarian aim of maximizing total happiness, counting everyone’s happiness impartially as of equal value, with no preference for ourselves or our loved ones.

Obviously, Greene’s argument flies in the face of right reason. Nagel explains how Greene tries to fudge the issue:

Utilitarianism, he [Greene] contends, is not refuted by footbridge-type intuitions that conflict with it, because those intuitions are best understood not as perceptions of intrinsic wrongness, but as gut reactions that have evolved to serve social peace by preventing interpersonal violence. Similar debunking explanations can be given for other commonsense moral intuitions, such as the obligation to favor members of one’s own group over strangers, or the stronger obligation one feels to rescue an identified individual who is drowning in front of you than to contribute to saving the lives of greater numbers of anonymous victims far away. According to Greene, it is understandable in light of evolutionary psychology that we have these intuitions, and for the most part it does no harm to let our conduct be guided by them, but they are not perceptions of moral truth, and they do not discredit the utilitarian response when it tells us to do something different.

As Nagel says, Greene is telling us to be more, or perhaps less than human:

While we cannot get rid of our automatic settings, Greene says we should try to transcend them—and if we do, we cannot expect the universal principles that we adopt to “feel right.” Utilitarianism has counterintuitive consequences, but we arrive at it by recognizing that happiness matters to everyone, and that objectively no one matters more than anyone else, even though subjectively we are each especially important to ourselves.

No one matters more than anyone else? Try explaining that to your husband, your wife or your children.

Many people take Greene’s ideas seriously, but they are perfectly unserious. He himself knows that, practically speaking, no one is going to starve his family to feed a bunch of strangers. No one is going to provide significantly less for his family in order to provide more for people who he knows nothing about.

For all I know, Greenne is trying to persuade people to give up more of their wealth in order to give it to the less fortunate. Perhaps he is really just arguing for higher taxes on the rich.

Greene explains his point of view:

If it seems absurd to ask real humans to abandon their families, friends, and other passions for the betterment of anonymous strangers, then that can’t be what utilitarianism actually asks of real humans. Trying to do this would be a disaster, and disasters don’t maximize happiness. Humans evolved to live lives defined by relationships with people and communities, and if our goal is to make the world as happy as possible, we must take this defining feature of human nature into account.

Nagel points out that Greene is:

… accusing himself of failing to live in accordance with beliefs that he accepts, beliefs about ideal values. 

It will make more sense if we see Greene as the kind of liberal who wants to spend more money on education and who wants all school to be racially integrated, but who sends his own children to racially segregated private schools.

What's good for the masses is not good enough for his family.

He holds to principles in order to assert his membership, not in the human species, but in the group of pious liberals who hold to the right dogmas and who vote the right way.

Let’s not call it science.