Sam Harris has been making the rounds promoting his new book on how science can determine morality. I saw him on The Daily Show promoting it and someone also recently linked me to this presentation at TED by him on the same topic. While many atheistic champions of modernity begrudgingly concede the moral argument--that morals can not be made sense of without God--they instead assert that 'morality' is only a human construction. That morals are relative. That we create right and wrong, it doesn't exist out there somewhere waiting to be discovered and defined. Harris wants to attempt to rescue morality on behalf of secular modernity. He makes the argument that morals can be made sense of based on naturalistic causality. By understanding the facts and applying reason to them. And that, given enough time and analysis, with all facts properly understood and accounted for (mostly in the field of neuroscience), morality can be defined precisely and exactingly by science.
While Sam Harris makes many statements that I essentially agree with in this argument--most specifically that moral questions do have right and wrong answers--the manner he goes about arriving at that conclusion is sloppy at best, and a complete non sequitur at worst. Throughout the presentation he uses a fallacious appeal--not to science, which he hardly gets into at all--but to supposed common sense or things that are 'obviously true'. Without ever showing why these supposedly obvious things are actually true. And while in almost every instance I agree with his common sense conclusion, there is groundwork laid in our collective conscious which is largely responsible for what we consider to be 'obviously true'. In many cases the 'obvious' answers that he points to are not deductions from scientific fact and reasoned argument but from a moral mindset inherited from Christianity. Of course post-Enlightenment it has taken various non-Christian forms, but it is the Christian event in history (along with the God-authored conscience) which informs and creates that moral sense. To be fair this doesn't invalidate his argument, my point is only that the argument is imprecise, dishonest and manipulative. The heart of his argument has another problem altogether.
Even if science could determine, for example, the objective answers for how to achieve maximum happiness for the greatest number of people it still won't have solved the problem of morality. It still won't have accounted for or dismissed the Ted Bundys or Islamic fundamentalists and their 'obviously wrong' answers. Harris is implicitly asserting a philosophical presupposition that has not been affirmed by science and couldn't ever be. Namely that the goal of this life is to live for as long as possible and to achieve maximum happiness for the most people while minimizing suffering for the most people. This is not the end of a syllogism, this is not a scientific fact, this is an assumption of Harris'. It's his starting point. And if the Taliban or Ted Bundy or the entire planet reject this presupposition out of hand, which they are entirely within their rights to do given an atheist worldview, then there is nothing compelling them to abide by the 'correct conclusions' of a materialist moral calculus. If they believe that the point of life is to cause death and destruction rather than to facilitate life and happiness then the atheist has no means for telling them that they are wrong, other than their own personal opinion. No amount of scientific data, no matter how comprehensive or conclusive, could ever show them to be necessarily wrong. All that Harris can (theoretically, though probably not actually) do is say 'Here are the guidelines to follow that best assist in humans flourishing and thriving'. Which A) is irrelevant to those who do not find value in humanity flourishing and thriving and B) is not an instance of science answering all moral questions, it is science answering a particular moral question given a presupposition of materialistic, humanistic utilitarianism. A presupposition that science has not and could never validate via empiricism and reason.
Science is the study of what physically is; morality is the question of what should be. What kind of world we want to fashion, how we should treat people, what we ought to do, what we ought not to do etc. Harris mentions in his argument the traditional view of many Western modern thinkers. That they accept that science can not determine morals or values. Harris then simply asserts--rather than demonstrates--that science can in fact answer these questions. When in reality the traditional view is exactly correct and Harris does nothing to refute or even address this traditional understanding. As David Hume put it "You can not get an ought from an is."