On the 20th anniversary of Earth Day, a major intellectual force behind that grounds-well of environmental concern observes that the environmental movement--along with the vast, expensive apparatus that grew out of that event--has failed. The reason, Commoner (The Politics of Energy, 1979, etc.) says, is that the environmental organizations and government regulators have been haggling over limits, standards, and controls for pollutants when they should be dedicated to prevention. That's a formidable job, but Commoner claims that today's environmental crises result from production technologies initiated since WW II and are thus, conceivably, reversible. Redesigning the postwar ""technosphere""--by recycling up to 90% of trash and substituting organic farming, decentralized solar electricity, mass transit, and nonpolluting cars, and natural materials for today's polluting technologies--could bring us into harmony with the ecosphere without threatening our economy or Third World development. The major obstacles are formidable--corporate power and devotion to short-term profits; government accommodation of the corporate agenda; and the American taboo against social intervention lead the list--but Commoner sees hope in the European Green movement, as well as in isolated but effective American consumer and citizen actions. Commoner's rational, radical diagnosis and prescription could well serve as a motivating agenda for Earth Day 1990. And without his hard green economic and political line, that occasion could be just one more exercise in toothless hoopla.