FRIENDS OF THE EARTH may condemn this book, but in fact it gives little comfort to their enemies. A journalist of no fixed ideology (his credits include The New Republic and National Review), William Tucker has compiled an informed and forceful critique of the "Age of Environmentalism," the decade that extends from Earth Day 1970 to Election Day 1980.

James Watt and David Brower, take note: Tucker does not say that environmentalism is dead, only that it aged too rapidly. Once the champion of liberal reforms, clean air and water for all, the movement has soured into truculent conservatism, espousing wilderness permits for a few -- and nuclear energy for none.

Tucker calls this mentality "aristocratic," noting its tendency to favor a narrow, privileged class -- suburbanites with Vibram soles -- and to obstruct material progress for the less fortunate. Progress and Privilege have locked horns, instead of marching together.

This argument is tough, ironic, and easily misunderstood. By protecting nature from human interference, Tucker says, environmentalists have sold both nature and humanity short. In nature, growth and decay are continuous: an acorn sprouts from dead leaves, a mountain erodes as it rises. People stand inside this picture, not outside; they must accept change if they hope to survive.

Tucker is no social Darwinist, a mindless advocate of survival-by-the-strongest; he is reminding us of what Darwin truly saw, that adaptation is nature's primary law. All creatures, great and small, face an uncertain future. Going on means accepting risks, letting go of empty traditions. Our choice is not between Paradise or Inferno, as the environmentalists warn. Tucker's vision is less static and despairing: "We must learn to love ourselves a little bit better before we can truly love nature as it is."

He balances this optimism with a blunt practicality. In crisp, clear prose, his chapters survey a broad array of topics: forests, birth rates, politics, science. Tucker has a knack for incisive summary, getting his terms straight, avoiding tired thoughts and phrases.

Along the way, he challenges many environmentalist fears: human populations are declining, other species and resources are holding on. The planet is tougher than we are; its systems are less fragile than we thought. Human activity -- new ideas, technology, rising wealth -- improves the environmental climate by making us more efficient and economical. Entropy, the loss of energy, is not an immutable law: every act of progress buys back energy, teaches us to slow its dissipation.

Does that sound like Mr. Micawber, who always said something good would turn up? Tucker does have some overzealous moments. At times he plays fast and loose with history, collapsing years and ideas to make his rhetoric work. He portrays "the wilderness ethic" as fairly recent: in fact it emerged after the American Revolution. He places the discovery of biological succession in this century; Thoreau published "The Succession of Forest Trees" in 1860, drawing on earlier sources.

These are minor flaws; of more consequence is Tucker's strenuous praise of progress. Change does not always advance us; his own evidence suggests that greed and illogic have often inspired reforms. For example, he admits that cities promoted warfare, but says they also fostered the great religions, "which have probably been humanity's greatest human achievement in resolving conflict and helping people to live together peacefully." Let us carry that news to Belfast, then on to Beirut and Baghdad.

What saves William Tucker from writing a tract is his own humanity, intelligence, and good humor. He gives the environmental movement full credit for its achievements: it aroused consumers, posted legitimate questions about waste and pollution, encouraged frugality on a national scale. But zero-growth has no future, he warns: we must learn again that science and technology are human tools, for human purposes; that the survival of a free and democratic culture depends on its enterprise and capital.

America has always stood for innovation, for the adventure of taking risks. The New World lives on hope, not doom; we must therefore hope Tucker is right, our progress gives the world "its brightest and best hope for a better future."