This text is designed for students who wish to explore in depth questions about how on earth we ought to live e.g., how we can behave responsibly toward nonhumans and toward the planet). Although primarily oriented toward questions of ethics broadly understood, and approached philosophically, the volume crosses disciplinary boundaries and attends seriously to economic reasoning and its implications for environmental policy issues. It seeks to extract for critical attention the relevant moral or normative presuppositions which lie behind policy recommendations, whether they are ones made by biologists, ecologists, economists, phiolsophers, engineers, public officials, or anyone concerned with policy decisions.