Here's my response (slightly edited):
Hi K--,
Thanks for linking me to Sam Harris' interesting TED talk. You asked my opinion on Harris' moral views. I think, first of all, that he's correct in rejecting relativism - In fact, he's one of the few atheists who does. He's correct in affirming that there are facts about human flourishing that obtain across cultures.
Where I disagree with him is in his belief that morality needs no supernatural sanction, that it can be derived solely from science. Here I think he misses several important facts and leaves unanswered some crucial questions:
1. He starts off by saying that he wants to base morality on science but then he defines morality as concern for human flourishing, This, however, is not a scientific claim, so in order to get his project going he has to build it on a non-scientific foundation.
2. Moreover, he never answers the question why we should privilege human flourishing over that of other species. Often the flourishing of humans comes at the expense of the flourishing of other animals so on what grounds does he elevate humans over other mammals?
3. More seriously, even if human flourishing is an appropriate criterion for morality, he doesn't address the metaethical question of why I should care about the well-being of other human beings. Why would it be wrong to just care about my own flourishing? Why should I help people I don't even know who are starving in Africa or sacrifice my comfort today to preserve the planet for people not yet born? Why would it be wrong to be an egoist who puts his own well-being ahead of that of all others? Science cannot answer that question and he doesn't answer it either.
4. Nor can science answer the question of what it even means to say that something is morally wrong in the first place. What does it mean to say that the Taliban are wrong to cover their women in burkas? What does "wrong" mean if we're all just the product of impersonal evolutionary forces that have shaped us to survive in the world? What does it mean to say that "X is wrong" if we're just machines made of meat doomed to die forever and there's no ultimate accountability for what we do? At most "X is wrong" can mean merely that some group of people doesn't like it.
The Judeo-Christian worldview offers the only satisfactory alternative to these shortcomings in Harris' Moral Landscape book. In Christianity (and Judaism) human flourishing is indeed paramount, which is why we're commanded by God to be compassionate and just in our dealings with others. Humans are privileged by the Creator of the universe because He purposefully creates them in His image and loves them specially.
God further commands us to care about others, even if it means sacrificing some of our own well-being to do so. In other words, He prohibits egoism and selfishness, and that's the only thing that could make these behaviors morally wrong.
Finally, on the Christian worldview we are told that we will ultimately be held accountable for our behavior by an omniscient, omnipotent, perfectly good moral authority. To violate His command to love is to violate the very fabric of creation and such violations will not go unnoticed. On Harris' view there's no reckoning for anyone who does anything that diminishes another person's flourishing, and with no accountability the word "wrong" is emptied of any significant meaning.
To say it differently, Harris is trying to hold on to Christian morality while yanking the foundation out from underneath it. He's piggy-backing on the will of God while insisting that God doesn't exist or is irrelevant. His is an interesting project, but like all such attempts to derive morality from a universe without God, it doesn't succeed.
