SAM Harris heads the youth wing of the New Atheists. "The End of Faith," his blistering take-no-prisoners attack on the irrationality of religions, found him many fans and, not surprisingly, a great body of detractors.

In? "Letter to a Christian Nation," a follow-up prompted by the responses of Christians unhappy with his first book, he set out, he said, "to demolish the intellectual and moral pretensions of Christianity in its most committed forms," and so acquired, no doubt, more friends and more enemies. Certainly both books have had a wide and animated readership.

His new book, "The Moral Landscape," aims to meet head-on a claim he has often encountered when speaking out against religion: that the scientific world view he favors has nothing to say on moral questions. That claim often keeps company with the thesis, elaborated by the evolutionary biologist Stephen Jay Gould, that science and religion have "non-overlapping magisteria." The authority of science and the authority of religion cover different domains, Gould thought, and the methods of each are inappropriate for the study of the other's problems. Religion deals with questions about what Harris calls "meaning, morality and life's larger purpose," questions that have no scientific answers.

Harris, who has a doctorate in neuroscience, disagrees. Only science can help us answer these questions, he says. That's because truths about morality and meaning must "relate to facts about the well-being of conscious creatures," and science alone - especially neuroscience, his field - can uncover those facts. So rather than consulting Aristotle or Kant (let alone the Bible or the Koran) about what is necessary for humans to flourish, why not go to the sciences that study consciousmental life?

Harris means to deny a thought often ascribed to David Hume, according to which there is a clear conceptual distinction between facts and values. Facts are susceptible of rationalinvestigation; values, supposedly, not. But according to Harris, values, too, can be uncovered by science? the right values being ones that promotewell-being.