Imagine that you are an environmentalist who passionately believes that it is wrong to drill for oil in the Arctic National Wildlife Refuge. How do you convince someone that a decision to drill is wrong? Debates about the environment and how humans ought to treat it have gone on for decades, yet arguments in favor of preserving biodiversity often lack empirical substance or are philosophically naive, making them far less effective than they could be. This book critically examines arguments that are commonly offered in support of biodiversity conservation. The authors adopt a skeptical viewpoint to thoroughly test the strength of each argument and, by demonstrating how scientific evidence can be integrated with philosophical reasoning, they help environmentalists to better engage with public debate and judiciously inform public policy. This interdisciplinary and accessible book is essential reading for anyone who engages in discussions about the value of biodiversity conservation.