If there is a hell, Sam Harris—author of The End of Faith and atheism's poster boy—is going there. But while the faithful may argue that godless scientists are doomed to soul-destroying nihilism, Harris' new book, The Moral Landscape, attempts to redeem the science-based worldview, arguing that it offers a clearer path to morality. Wired called Harris—from out of lightning-bolt range—to discuss his argument.

What do you mean by "moral landscape"? It's a framework in which we can talk about the most important questions in scientific terms—questions that relate to human and animal well-being. For instance, we in the developed world have a different notion about how to live a long and healthy life. That's because we have a science of medicine, which gives us an understanding of the mechanics of disease processes and how to address them.

How can you scientifically determine whether something is good or bad? The science of morality is about maximizing psychological and social health. It's really no more inflammatory than that. Obviously it would be a good thing to stop nuclear proliferation and genocide and climate change, and to better educate our children. These are things that would be good for everybody and bad for nobody. People seem to believe that there's no ground for truth-claims about human values—that these are not the sort of facts that science can ever deal with. But there is a place for science to argue, for instance, that the Taliban is really wrong. Its beliefs lead to unnecessary human suffering. Any conception of human well-being you could plausibly have, the Taliban patently fails to maximize it.

Religion makes those sort of truth-claims all the time. But religion is precisely the wrong software for analyzing human well-being. It's the one area of our lives where people win points for saying, "I'm not going to change my mind no matter what happens."

But hasn't religion made some people behave more morally? The problem is that religion tends to give people bad reasons to be good. Is it better to alleviate famine in Africa because you think Jesus Christ is watching and deciding whether to reward you with an eternity of happiness after death? Or is it better to do that because you actually care about the suffering of your fellow human beings?

Why is science a better alternative? Science is the most durable and nondivisive way of thinking about the human circumstance. It transcends cultural, national, and political boundaries. You don't have American science versus Canadian science versus Japanese science.

Science has suffered when it's seen as the enemy of religion. But in your book you criticize scientists who have tried to build bridges. A religious scientist is someone who has decided he can behave rigorously in his scientific profession but has no obligation to connect that way of thinking to his larger worldview. If he did, he would notice contradictions between his science and his religion. Besides, the point is not to get religious people to accept evolution—it's to get everyone thinking honestly about the nature of the world.

A lot of people must hate what you're saying. Do you worry about your personal safety? I take security seriously, and I've gotten my share of weird emails. I don't tell people where I live.