BOOK REVIEW / SCIENCE : Arguing for the Superiority of Science Over the Metaphysical : RIVER OUT OF EDEN: A Darwinian View of Life <i> by Richard Dawkins</i> ; Basic Books $20, 172 pages

Many scientists eventually become dewy-eyed about the beauty of the universe and nature’s laws. Awe and wonder lead them to metaphysical speculations about how and why everything has come about.

No less a scientist than Albert Einstein said, “The most beautiful and the most profound emotion one can experience is the sensation of the mystical. It is the source of all true science.” He was not alone. For many, the discoveries of science lead to the question, “Why does the universe exist?” and to similar unanswerable conundrums.

But Richard Dawkins, a biologist at Oxford University, is not one of those scientists. He will have none of it. He has no use for mysticism, metaphysics or theology.

Dawkins is a militant atheist, and he scoffs at any hint that there is meaning or purpose or design to what we discover in the world. Science is all there is, and science is all there needs to be. All other explanatory systems are superstition.

The existence, development and complexity of life is an accident of chemistry, he says. How it happened was explained by Charles Darwin, and “never were so many facts explained by so few assumptions.” After Darwin, there is no need for God.

Dawkins’ latest book, “River Out of Eden,” is a beautifully crafted, superbly written exposition and explanation of this view. He presents the counter-arguments, and one by one, he dismantles them.

Some argue that modern science is just another belief system, the myth of Western culture, and that evolution is indistinguishable from the creation myths that all civilizations have. To them Dawkins says:

“Scientific beliefs are supported by evidence, and they get results. Myths and faiths are not and do not.”

“Western science, acting on good evidence that the moon orbits the Earth a quarter of a million miles away, using Western-designed computers and rockets, has succeeded in placing people on its surface. Tribal science, believing that the moon is just above the treetops, will never touch it outside of dreams.”

Some argue that complex organs--the eye, for example--could not have evolved gradually by natural selection because half an eye or a quarter of an eye provides no evolutionary advantage. What’s more, it is inconceivable that a fully functioning eye would spring forth by mutation in a single generation.

To them Dawkins says:

Who says that an eye has to be perfect in order to work at all? Who says that one-quarter of an eye is no improvement over no eye? In a series of brilliant case studies Dawkins demonstrates that a slight change can indeed be an advantage.

Furthermore, we must remind ourselves repeatedly of the incomprehensible amount of time that has elapsed since life began on Earth. A statistical study that he cites has determined that “it would take less than half a million years to evolve a good camera eye.”

As a result, Dawkins says, “it is no wonder the eye has evolved at least 40 times independently around the animal kingdom. There has been enough time for it to evolve from scratch 1,500 times in succession within any one lineage.”

For centuries, many people have argued that the intricate design we observe in nature could not have occurred by accident. To many people, this “Argument From Design” is the strongest argument for the existence of God.

Dawkins dismisses it with a wave of the hand: “The true process that has endowed wings and eyes, beaks, nesting insects and everything else about life with the strong illusion of purposeful design is now well understood,” he says. “It is Darwinian natural selection.”

And as to those existential questions about, “Why is there something rather than nothing?” Dawkins writes:

“I have lost count of the number of times a member of the audience has stood up after a public lecture I have given and said something like the following: ‘You scientists are very good at answering ‘how’ questions. But you must admit you’re powerless when it comes to ‘why’ questions.’

“Behind the question there is always an unspoken, but never justified implication that since science is unable to answer ‘why’ questions, there must be some other discipline that is qualified to answer them. This implication is, of course, quite illogical. . . . Questions can be simply inappropriate, however heartfelt their framing.”

I don’t want to give the impression that this book is a polemic, because it is not. Most of it is a carefully reasoned, meticulous presentation of how evolution explains biology, with equal credit to Darwin and to James Watson and Francis Crick, who unraveled DNA some 40 years ago.

When Darwin published his Theory of Evolution in the mid-19th Century, he did not have a clue about the mechanism of heredity. A hundred years later, Watson and Crick figured out how heredity works on the molecular level, and it turned out to be one of the greatest examples of confirmation in the history of science.

Every living thing on Earth has the same genetic code in its genes. The genes themselves differ, but the building blocks are all the same. The animals that Darwin had placed closest together based on their outward appearance are most similar in the DNA of their cells. Watson and Crick, Dawkins says, “should be honored for as many centuries as Aristotle and Plato.”

DNA is not just the mechanism of life. It is all there is. The “purpose” of life is to pass DNA from one generation to the next. Nothing more nor less.

“Nature is not cruel,” Dawkins writes, “only pitilessly indifferent. This is one of the hardest lessons for humans to learn. We cannot admit that things might be neither good nor evil, neither cruel nor kind, but simply callous--indifferent to all suffering, lacking all purpose.”

Dawkins has gone to the heart of his subject and presented it with energy, insight and verve.