In 2006, the German government decided that it was legally forbidden for a bystander to shoot down a known terrorist plane even if bringing the plane down resulted in the saving of thousands and resulted in only a hundred dead. The government's logic: it is impermissible to harm another even if the goal is to save the lives of many. This decision flies in the face of Saint Thomas Aquinas' doctrine of double effect, as well as the common intuitions of many who look at this kind of case. Clearly, many Americans had a different view of this situation soon after it actually happened at the World Trade Center. But why would the German government make a decision that rejects the eloquence of a saint and the thousands of people who intuitively support his doctrine?

For starters, governments and other legal institutions have a long standing tradition of rejecting folk intuition as well as the trendy beliefs of the day. Less than 50 years ago, well educated people in Europe and the Americas believed that harming an animal for the benefit of mankind was no different than harming a potato. Animals had no sense of self, no feelings, no capacity to anticipate the future or reflect on the past. Absent these abilities, experimentation on animals lacked ethical pull. Today, we know better and there are strict laws against experimentation on animals. We have, in the words of the philosopher Peter Singer, expanded our moral circle. A second reason why governments often rise up against intuition is that intuitions can often lead to disastrous consequences, as our psychology falls prey to statistical illusions, thinking that a 5% fat diet is worse than a 95% fat-free diet, or that a policy that states it will eliminate welfare handouts is worse than a policy that states it aims to make everyone self-sustaining.

But the problem that interests me, and is summarized in my book Moral Minds, is why we have particular moral intuitions and how an understanding of the evolution, development, and neural substrate of this intuitive system can greatly inform, and potentially transform our legal and educational systems. Consider the terrorist bombing example, along with other moral dilemmas that involve harming one or few to save many. When we ask people from different countries, with different religious backgrounds and educations, to generate judgments about such cases, we find, based on studies conducted on the internet (moral.wjh.harvard.edu), quite uniform and seemingly universal responses. Surprisingly, perhaps, many of their judgments not only appear immune to cultural variation, but mediated by principles that are inaccessible to conscious awareness. That is, underlying our intuitive moral judgments appears to be a system that I, together with the philosophers John Mikhail and Susan Dwyer have called our universal moral grammar, an expression that makes explicit the analogy between language and morality, an idea that can be traced to the political philosopher John Rawls. If the analogy is correct, then several predictions follow: the core principles of our moral grammar should be part of the child's innate capacity, the process of acquiring the native moral system should be fundamentally different from the process of acquiring a second moral system later in life, and we should be able to identify a suite of neural structures that are dedicated to moral analysis, or what I refer to as the moral organ. We are only at the very beginning stages of tackling these problems, with suggestive evidence accumulating rapidly, especially in terms of the relevant brain structures.

One spin off of the analogy to language is that our moral calculus relies not on emotion, but on our ability to compute, for any morally relevant situation, the relationship between intentions, causes, and consequences. On this view, emotions are epiphenomenal, flowing out of our moral judgments as opposed to causing them. Thus, psychopaths, who have clear emotional deficits, might do the wrong thing because they lack the requisite emotional input into moral judgments or, because their emotional deficit leaves them without the requisite breaks to stop them from doing the wrong thing. Which view is correct is critical, not only for academics sitting in the ivory tower, but for lawyers and legal scholars concerned with understanding notions of responsibility and free will. If emotions are not causally necessary for moral judgments, then psychopaths know what is right and wrong, but simply can't stop themselves from killing others. Though our studies of psychopaths are incomplete, we have studied a population of patients that illuminates the role of emotion in moral judgments. These patients, carefully studied by the neuroscientist Antonio Damasio and his colleagues, have extremely flattened social emotions as a result of damage to a region of the frontal lobes. When my colleagues and I recently tested these patients with a variety of moral and non-moral dilemmas, we found two striking results. First, for a large number of these dilemmas, including some that were highly emotional, the frontal lobe patients showed normal patterns of judgment. In these cases, therefore, emotions do not inspire our moral judgments. Instead, we deliver our verdict in a cold, dispassionate perspective, guided by analyses of others' beliefs, desires and goals, and the outcomes that emerge.

Second, for a selective set of moral dilemmas involving personally killing one person in order to save many, the frontal patients are much more likely than normal subjects to favor the utilitarian outcome. That is, they prefer actions that lead to the greater good, as in saving the greatest number of lives, even if the action involves personally killing someone. From this pattern of choices we derive a striking conclusion: hyper-utilitarian decisions emerge when the anti-utilitarian pull of an aversive or negative action is knocked out. On the other hand, if your philosophical biases lean you in a utilitarian direction, you will have a different interpretation: what is normal is to flatten your emotional response in order to see clearly the benefits of the overall good.

These studies only skim the surface of current knowledge, and more importantly, only touch on a fraction of the questions that we can address by using the methods of science, and especially cognitive and neuroscience. For example, it is well known that many patients suffering from Huntington's disease experience a relatively selective deficit for disgust, but not other emotions. That is, they neither experience disgust when presented with objects (e.g. vomit, feces) or situations (e.g. incestuous relations, licking a toilet seat) that most find disgusting, nor do they recognize facial expressions of disgust in others. This deficit presents a unique opportunity, which we are pursuing, to look at the relationship between negative emotions such as disgust and its causal role in guiding moral judgments. In particular, we can follow up on an interesting proposal by the philosopher Shaun Nichols that the key difference between moral and other conventional problems is that the moral domain emerges when strong emotions such as disgust combine with powerful social norms.

To clarify the relationship between emotion and social norms, consider the following scenario. You are at an elegant dinner party when your host, James, says “I can see that some of you are feeling sick tonight. If you want to cough up your phlegm into your wine glasses, please go ahead.” For most of us, this image immediately invokes a disgust response, and we rapidly converge on what appears to be a strict moral verdict: “No, James can't allow this. It is forbidden to hack up your phlegm.” Though James would seem to have the authority to override this bit of etiquette, our response suggests that he has violated a much more severe code, a moral code. As Nichols suggests, disgust penetrates the conventional and functionally transforms it into a moral issue. Back to Huntington's: if this disorder knocks out disgust, these patients should be perfectly fine with James' proposal, treating it as a conventional change, no less upsetting than if James had proposed that we can eat with our hands rather than our forks. Stay tuned as the answer to this question is forthcoming.

What about the German people, and the problem that launched this essay? Given the government's decision to block attacks on terrorist controlled planes – a decision mediated by an attempt to maintain the largely anti-utilitarian logic of the German legal system – are Germans intuitively anti-utilitarian, as a population? I would bet good money that the answer is “No.” My confidence stems from the logic of the linguistic analogy, and the relative immunity of the moral organ to doctrinally explicit systems, including not only law but religion. Thus, in addition to my prediction about the German people, I am also willing to wager a bet that religion will make equally weak inroads into the intuitive system. So far, this prediction appears correct, especially if one contrasts people of faith with atheists, and explores judgments focusing on unfamiliar moral problems as opposed to well-rehearsed cases – abortion, euthanasia, infidelity.

Our capacity to generate moral judgments is part of our evolved hardware and software. It is a system that triggers judgments of right and wrong, unconsciously. The principles that lie at the core of this moral organ are often locked away, inaccessible to conscious reflection. Formal institutions such as our governments and religions must not subordinate themselves to this system. But ignoring it is equally ignorant. We must understand our intuitive moral systems so that we can prepare ourselves for cases of confrontation, and ultimately, design systems that move us from the descriptive to the prescriptive, helping to shape a society that we consider more virtuous and more respectful of the lives of others.