Why is cost-benefit analysis so controversial?

The cost-benefit principle says we should take those actions, and only those actions, whose benefits exceed their costs. For many, this principle's commonsensical ring makes it hard to imagine how anyone could disagree. Yet critics of cost-benefit analysis are both numerous and outspoken. Many of them argue that cost-benefit analysis is unacceptable as a matter of principle. I begin by noting why many find this argument largely unpersuasive. I then examine several conventions adopted by cost-benefit analysts that do appear to yield misleading prescriptions. Finally, I consider the possibility that the cost-benefit principle may itself suggest why we might not always want to employ cost-benefit analysis as the explicit rationale for our actions.