On the value of natural ecosystems: The Catskills parable.

Economic considerations typically have led societies to develop rather than to preserve wild and natural places. Accordingly, preservationists traditionally have based arguments for protecting nature on its intrinsic rather than instrumental worth. These traditional arguments rest on aesthetic, moral, and spiritual rather than on economic values. Today, though, many environmentalists point to the preservation of nature's "services" as the reason to protect ecosystems from conscious manipulation or careless degradation. Many cite a decision by New York City to spend over $1 billion to purchase land in the Catskills watershed to secure or restore the capacity of the natural ecosystem to purify the City's water supply. This essay questions the validity of this example and, in turn, the generalizability of the thesis it has widely been thought to support.