A term referring to the theory that, when a group of people collectively own a resource, individuals acting in their personal self-interest will inevitably overtax and destroy the resource. According to the commons theory, each individual gains much more than he or she loses by overusing a commonly held resource, so its destruction is simply an inevitable consequence of normal and rational behavior. In the study of economics, this idea is known as the free rider problem. Human population growth is the issue in which the commons idea is most often applied: each individual gains personal security and wealth by producing many children. Even though each additional child taxes the global community's food, water, energy, and material resources, each family theoretically gains more than it loses for each additional child produced. Although the theory was first published in the nineteenth century, Garrett...