Is cost benefit analysis an effective tool in environmental disputes? How do we measure the costs and benefits? How do we know what benefits we might gain from saving endangered species? Or improving visibility at the Grand Canyon? In the Entergy case, how does the EPA calculate the benefits of not squashing fish against intake screens? Should you survey people to ask them how much it is worth? Or just think in terms of lives saved or sick days avoided? Or should we protect the environment regardless of cost?