People by and large are concerned with and pursue self-interest. They are unlikely to be motivated under a prudent and sustainable fashion. They are unlikely to be motivated under the following conditions: if their resources are limited, or if the degradation of any particular portion affects them very little; or if they have vast, or that degradation of any particular portion affects them very little; or if they have vast, or that degradation of any particular portion affects them very little; or if they have open before them possibilities of substitution as any one resource element is depleted, or if their control over the resource base is tenuous, so that others may, at any time, deplete a resource they value, even if they use it in a restrained fashion. Indeed, exhaustive use is highly likely when any one of these three conditions obtains. It is only when people perceive their resource catchments as limited, and their control over the resource base as not readily feasible, and when they are motivated by the necessity of maintaining the resource base in a locality, retaining control over their resource base are most likely to fulfill three prerequisites for sustainable resource use; and therefore to behave in ways conducive to the conservation of biodiversity within their localities. When do people use resources exhaustively?