Never before have questions about our relationship with the environment loomed so large in human affairs. Is the world at an historical threshold, where we risk dooming ourselves and our planet if we don't change the way we exploit the Earth's resources? Or are environmentalists being alarmists, underestimating nature's resilience and humanity's adaptiveness? Is species extinction something we really need to worry about? Can we find new supplies or substitutes for scarce resources? Norman Myers, an award-winning environmentalist, and Julian Simon, a University of Maryland economist and outspoken skeptic on environmentalism, are at polar opposites on these questions. This book is a transcript of their provocative exchange in a debate held at Columbia University in October 1992. The authors also provide position statements and replies that let readers judge for themselves whose arguments are more persuasive. This book makes a brief, stimulating guide to a most important issue.