With this simple conviction, FOREIGN POLICY asked eight leading thinkers to issue an early warning on the ideas that will be most destructive in the coming years. A few of these ideas have long and sometimes bloody pedigrees. Others are embryonic, nourished by breakthroughs in science and technology. Several are policy ideas whose reverberations are already felt; others are more abstract, but just as pernicious. Yet, as the essays make clear, these dangerous ideas share a vulnerability to insightful critique and open debate.