In his arguments for a science of morality, Sam Harris relies heavily on the following analogy: well-being is to morality what health is to medicine. His claim is not simply that morality is a natural phenomenon which can be studied as rigorously as any other. Rather, it is that moral prescriptions can be as scientifically grounded as medical prescriptions. That there is no basic difference between a doctor giving a patient medicine and a moral scientist prescribing right conduct.
Of course, when a doctor says, "take two and call me in the morning," she is, in a sense, prescribing right conduct. She is telling her patient what to do. More often than not, I think, the patient trusts her to give good medical advice. That is, the patient is listening to the doctor precisely because he wants to recover from some malady, and believes that the doctor knows how to help him get over it. The prescription would not be morally binding unless we were to suppose that people had a moral obligation to do what their doctor says. But that is not an attractive moral principle. Our doctors tell us what is best, and--even when we believe we have been given the best available medical advice--we are left to decide whether or not taking that advice is something we should do. Medical advice is not morally binding. Doctors don't prescribe right conduct in the moral sense of "right."
If the advice of moral scientists is just like the advice of medical doctors, then it is not morally binding. Indeed, the sort of advice Harris defines as "moral" is just advice about how to promote well-being, and that seems to be health, or a particular sort of health--perhaps mental or emotional health. But now we have a problem. Advice about well-being was supposed to tell us what was morally correct. But if the science of morality is just like medicine--if it is just the science of well-being--then this "moral" advice is not morally binding. Even if moral science tells us what is right and wrong, it is ultimately up to us to decide whether or not it is right or wrong to follow the advice of moral science. Moral science is no better than any branch of medical science when it comes to making moral prescriptions. Once you start discussing the morality of these prescriptions, you are no longer pursuing science.
There is a big difference between ordinary medical prescriptions and the sorts of moral prescriptions Harris is talking about. He is talking about prescriptions based on how our actions are likely to affect other people. Instead of telling us what we should do to promote our own health, Harris' moral science would use the same medical science to tell us what we should do to promote the health of other people. By shifting the focus from ourselves to other people, we find a lot more room for moral responsibility. However, while the moral scientist may appeal to our sense of social responsibility (or familial responsibility, or global responsibility, or what have you), the science does not provide or ground any such sense of responsibility. Science does not tell us what we should value.
We need something more than science to get us from medical science to moral judgment. This is Harris' most profound failing; but his entire discussion of health is confused. In his recent defense of his book, he ridicules the following three claims:
(1) "There is no scientific basis to say that we should value health, our own or anyone else's."
(2) "Hence, if someone does not care about health, or cares only about his own and not about the health of others, there is no way to argue that he is wrong from the point of view of science."
(3) "Even if we did agree to grant "health" primacy in any discussion of medicine, it is difficult or impossible to define it with rigor. It is, therefore, impossible to measure health scientifically. Thus, there can be no science of medicine."
Yet, (1) and (2) seem true to me. Of course, you could use science to make an argument that somebody should value health, but your scientific argument is not binding on all rational people--not even on all rational people who value science. The problem is, your scientific argument will only be relevant to people who share some other values--values which go beyond the basic value set of science itself. As for (3), it is false, but not for the reason Harris supposes. It is not difficult to define "health" with rigor. Medical science has a rigorous, working definition of "health." According to the NIH's online medical dictionary, health is:
the condition of an organism or one of its parts in which it performs its vital functions normally or properly: the state of being sound in body or mind; freedom from physical disease and pain.This is a working definition only in the sense that we are still learning about some of the functions of our bodily organs, not in the sense that we might one day discover that "health" doesn't mean what we thought it meant.
Harris rejects (3) for a less compelling reason. He claims that we can study health scientifically even though we lack a rigorous definition of it. He denies that we have a rigorous definition of "health," and thus concludes that you don't need a rigorous definition to pursue something scientifically. Thus, he says, the fact that we lack a rigorous definition of "well-being" should not prevent us from studying it scientifically. But we do have a clear, rigorous, and uncontroversial medical definition of "health."
Harris' argument for moral righteousness comes down to his claim that facts about general well-being are morally binding, that what is morally right is always and only what most promotes general well-being. This is the "ought" he says is beyond reproach. But it isn't beyond reproach. Despite the problems with defining "well-being" indicated in the previous paragraph, I'm not convinced that the worst possible scenario is one in which all sentient beings suffer for as much and as long as possible. I (and others from various cultural backgrounds I've asked) would rather see everybody suffer equally than see a universe where a planet of sadistic aliens caused the worst possible suffering for the rest of the sentient creatures in the universe, and relished it as one might a Thanksgiving or Christmas feast. Morality might best be thought of in terms of fairness or dignity, and not well-being--which is not to say that well-being is unimportant or irrelevant for a great many of our moral concerns. While many of our values certainly involve concerns about well-being to a large extent, they are not obviously all reducible to them. Furthermore, even those values which are reducible to concerns about well-being are not clearly reducible to a concern for universal well-being. And whether or not they should be is not a question of fact.
The best we can say is that the science of well-being (taken as the science of health itself, or specifically as mental or emotional health) can help us make informed decisions on a wide range of issues. However, it cannot prescribe right action in any morally binding sense. It cannot tell us which creatures we are morally obligated to care about. It cannot tell us what we should value without appealing to what we already value. And, again, while it may be obvious that we should value the promotion of general well-being, it is not obvious that this should be our primary--let alone our only--concern. All science can do is tell us what the likely consequences of our actions will be. That's good medicine, but it's not what Harris is selling.