In his essay, "Resources and Environmental Policy," Jan Narveson claims that, "there are no global shortages of anything that we have to worry about." In this claim he makes two basic assumptions about resources. The first assumption concerns infinite substitutability; no matter what we need, we will always be able to find something else that will work just as well or better. The second assumption concerns infinite technological advancement; we will always be able to invent something that will either allow us to use a resource more efficiently and extend its life span, or we will invent something that will allow us to exploit a new resource and thus render the previously scarce resource obsolete. The major problem with Narveson's argument is that he assumes we must look forward for these substitutes, that they will come about as we need them. He could have made a much more...