Does religion have any role to play in your moral universe?
No more than a belief in the gods of Mount Olympus does. Of course, I'm not denying that religious people occasionally do very good things on the basis of their faith. But even here, religion has given them bad reasons for being good, where good reasons are actually available. Of course, human consciousness allows for a wide range of contemplative insights and experiences of self-transcendence. But even the most rarefied mystical experience must depend, in some way, on the laws of nature - and such experiences can, therefore, be talked about in terms that do not insult our growing understanding of the universe.
Does postmodernist relativism, the belief that one woman's bikini is another woman's burka, muddy the moral waters?
Yes, I think that moral relativism - the idea that right and wrong depend entirely on one's cultural context or personal preference - is intellectually bankrupt and genuinely dangerous. The moment we connect morality to questions of human and animal well-being, we can see at a glance that the Taliban are advocating an obscene distortion of morality. To not judge the Taliban from the point of view of science is tantamount to saying that we know absolutely nothing about human well-being. It's like saying: "We've got 150 years of psychology, neuroscience and sociology to draw from - and we've made some very impressive gains on civil rights - but maybe, just maybe, forcing half the population to live in cloth bags and beating them or killing when they try to get out is as good as anything we've come up with." This form of "tolerance" or "contextual understanding" is pure, masochistic stupidity.
In doubting whether we can talk about human values and moral truth scientifically, we are essentially saying that when we do our best thinking, when really try to get our biases out of the way and are most committed to careful observation and honest reasoning, these efforts have no application whatsoever to the most important questions in human life. That should seem ridiculous on its face.
How, then, might we begin to resolve conflicting moral claims?
That's rather like asking how we resolve conflicting beliefs about epidemiology. What do we do when we come across people who deny the germ theory of disease? There is no easy answer. But when the stakes are high, we take steps to protect ourselves.
You say that changing people's ethical behaviour is the most important task now confronting us? Why?
I think the greatest challenge facing our species is to build a global civilization based on shared values. To do this, we will need to think about questions of right and wrong and good and evil in a common framework, purposed toward human flourishing. The alternative is for us to waste our time debating things like gay marriage, while problems like nuclear proliferation, energy security and climate change go unaddressed.
How would you propose going about beginning to make such changes? What, for instance, would you say to a Taliban leader who believes so strongly that women should not be educated that he's willing to burn schoolhouses, or kill homosexuals and apostates. How would you convince him that your moral landscape is superior to his?
The failure to convince everyone never counts against the truth of a proposition. It's been 150 years, and we still can't convince a majority of Americans that evolution is a fact. This hasn't put the science of biology in jeopardy.
How would a scientific approach bolster your argument?
A science of human well-being would be part of a maturing science of the human mind. Just as advances in medicine have ended certain arguments about the origins of disease, without really seeking such rhetorical effects, advances in psychology and neuroscience could change the way we think about our own subjectivity and the possibilities of finding happiness in this life. Imagine how our view of the human condition would change if we ever found a cure for racism, xenophobia and other forms of bigotry. What if there were perfectly safe ways to increase feelings of compassion and altruism? I think interventions of this sort - pharmacological and otherwise - are probably in our future. Neuro-imaging technology could also change our lives profoundly. We will probably develop reliable lie detectors, so that when the truth really matters, it will be impossible for a person to lie. This will change politics and diplomacy rather profoundly. There is no telling how developments of this kind could put pressure on popular beliefs.
This interview has been edited and condensed.