Resources as a Constraint on Growth
回顾了美国经济从资源丰富的“牛仔经济”转向资源受限的“飞船经济”的历程，分析了资源稀缺对增长模式的挑战，并批判性地评估了关于增长极限的理论模型及其假设的可靠性。
For a considerable part of its history, the American economy has functioned as a cowboy economy. It has been a cowboy economy in the sense that there have been no important resource constraints on growth. This is not to say that land, minerals, and a clean environment have been freely available. Rather, agricultural land could be obtained at roughly constant costs; most essential minerals have been present at fairly high grade in considerable abundance; and the environment could be used as a sink without becoming fouled. In the last several decades, however, cropland has stayed almost constant. Some high grade mineral deposits have been exhausted, and the carrying capacity of our environment has been strained. The scarcity of resources has led many to argue that the operating rules of our economy must change. Whereas in the cowboy economy we could afford to use our resources profligately, the new view of economic growth is that the closing of all our frontiers means that we are now operating in a spaceship economy. In a spaceship economy, great attention must be paid to the sources of life and to the dumps where our refuse is piled. Things which have traditionally been treated as free goods-air, water, quiet, natural beauty-must now be treated with the same care as other scarce goods. It would seem difficult to question the observation that the world economy is progressing toward a closed system. Many have carried this observation further, describing a future imperiled by famine, depleted of essential materials, running out of energy, or choking in its own exhaust fumes. Behind these pessimistic visions is a deeper skepticism about the very fruits of economic growth. Economists have for the most part ridiculed the new view of growth, arguing that it is merely Chicken Little Run Wild. I think that the new view of growth must be taken seriously and analyzed carefully. What have we learned about the new view? The first set of studies relates to theoretical investigations. (By theoretical I mean propositions based on largely untested assumptions about model structure -perhaps hypothetical would be a more accurate term.) In this category belong the celebrated writings sponsored by the Club of Rome as well as many offshoots of this work (Jay Forrester, Dennis H. Meadows et al.). These works have demonstrated that, under certain conditions involving technology, population, and resource availability, a sustained growth path for consumption is not possible. The conclusions of these works have not generally been accepted by economists because of the dubious nature of many of their assumptions. In particular, the assumptions regarding population growth and are quite unsatisfactory. Several authors have shown that the conclusions of these models are not robust to minor modifications in structure. Thus R. Boyd showed that introducing a new factor called technology would drastically alter the model's path. My work (1973a) showed that any of three changes in model structure-ongoing technological progress, adequate factor substitution or population decline-would lead to opposite and more optimistic results. It should be stressed, however, that all * Yale University.