A NEW THEORY OF ENDOGENOUS ECONOMIC GROWTH
指出，将投资区分为模仿性投资和创新性投资在增长理论中难以操作，主张所有投资都包含创新与模仿的混合，且因投资改变世界并创造临时垄断，导致平均利润率高于边际利润率，产生投资外部性，对政策有启示。
The advance of useful knowledge is widely agreed to be the key factor in explaining economic growth. While many writers have sought to distinguish between "ordinary" investment, which merely imitates existing assets, and research or educational expenditures, which result in innovation, it is argued in this article that this distinction has not been made operational for a theory of economic growth, and it is very doubtful whether it can be. Instead, it seems better to recognize that all investments consist of both one innovation after another and one imitation after another, in varying proportions which cannot in aggregate be identified. Since investment changes the world, and leads to unforeseen new investment opportunities, it results in temporary monopolies as Schumpeter pointed out. Because of these monopolistic profits, which also exist because of ordinary market imperfections, average profitability exceeds marginal profitability and there is an externality to investment, with policy implications. Copyright 1992 by Oxford University Press.