The utility of any moral system is surely measured in its ability to help make moral decisions from first principles. If it can't do that, then what's the point? This is one major problem I have with forms of divine command theory, its predicated on what that which is divinely-commanded, yet how can we establish what is divinely-commanded and what isn't from first-principles? It's a non-starter, instead a platform which people who have presuppositions about what constitutes divine knowledge push it as absolute truth.
I can agree with Sam Harris that religion does not provide a good framework for questions of morality. I can stand with him in condemning the action throwing battery acid in a child's face for learning to read as being morally wrong. I can even agree with him that there are certain actions that are better than others, and certain actions that would do nothing but cause harm, and even to the point that some of these create moral obligations. But I disagree that science is the foundation of such statements, or that it should be treated as such.
My problem with Harris is two-fold. First is that by calling it a scientific issue is writing off the importance of philosophical contemplation even when there's empirical considerations. Philosophers from Anthony Appiah to Simon Blackburn have taken Harris to task over this issue. Second, and more importantly, what he's advocating is useless.
I think the best that could be said for Harris' position is that it frames morality in real terms, taking the talk away from abstracts and into a view that is accessible. And for examples of moral horrors, like female circumcision or ritual sacrifice, it allows for saying its wrong for factors that are external to cultural authorities.
But now that we've granted that, then what? How do we apply such a framework to issues like euthanasia or abortion - two issues that provoke great passion from people on both sides of the issue. Is it even possible under what Harris is proposing to calculate objective answers to such questions? I'm sceptical because I don't think we could ever calculate it; there would always be a dispute between the weighting of certain factors and what are the relevant considerations of well-being. And no amount of data collection, to me it seems, is going to resolve the issue. And that's assuming that data-gathering is something practical to begin with.
Even down to Harris' pet example, the burka. Let's say we put burka wearers in fMRI machines and it turned out that 75% of them had a positive response to the burka, while 15% were neutral and 10% a negative one. Would that then make it moral? What if the numbers were slightly different? What about other factors like social cohesion or a diminished sense of worth, a lesser prosperity overall? If you ask most people who are against a burka why, the standard answer would be that it oppressed women.
In a discussion with Richard Dawkins, Harris tried to interpret the results of the trolley problem in terms of a consequentialism taking into factors such as mental anguish we might feel if we did such an action. Pushing a rally fat man off a bridge into the path of a trolley might lead us to mental anguish, but what of the years of potential medical operations for the morbidly obese man and his family watching on as he slowly gets worse - perhaps the doctors who would otherwise have to intervene in bypass surgery might be thankful for not having to participate in such operations. Not to forget the tax / insurance burden which helps collectively many people, but perhaps producers of food might suffer.
I can agree with Harris that science has a role in moral decision making, after all we are talking about how our behaviour affects others. Our nature is relevant to moral decision making, it would make no sense to have moral prescriptions that weren't relevant to our nature. Likewise, an understanding of consequences for our actions is very important too. The various empirical disciplines if they're not informing our moral decision making to my mind make us weaker for it.
But in terms of having a practical means of making moral decisions, what Harris is advocating doesn't really help. Moral reasoning has to have that utility, that ability for us to take such a view and apply it to how we act. I can accept the premise that Harris puts forward, but it's hardly substantial enough to put into good use. If the goal is just to have some grounding for right and wrong to overcome moral relativism and divine command theory, then I have no problem with what Harris is putting forward. But that's only the first step, and a step that has been dealt with by many moral philosophers the world over.