In 1972, the landmark Declaration of the United Nations Conference on the Human Environment laid out an ambitious set of principles to effect preservation and protection of the environment. One of the primary ethical principles espoused in the declaration was an obligation to protect and preserve the planet for the enjoyment of future generations. More recently, the Bemidji statement on Seventh Generation Guardianship has proposed that we look well into the future in considering the consequences of our present actions. As the environmental movement has come of age since the 1970s, this idea of our ethical obligation to future generations has occupied a central place in the moral foundation for environmental protection. This article explores key philosophical disagreements that have arisen over thinking about obligations ...