Marx's contributions and their relevance today
梳理了马克思对政治经济学的七项主要贡献，包括唯物史观、劳动价值论、资本积累理论等，并指出资本主义的周期性危机是内生的、不可消除的，对理解当代资本主义仍有参考价值。
Karl Marx made at least seven major contributions to political economy. First, he established a framework-the materialist conception of history-for analyzing economic, social, and political changes over long periods of time. Marx showed that a society's social or class relations ultimately became impediments to the further development of its productive forces. In order for the productive forces to gain the conditions for their further advance, the rising class associated with the economic expansion would have to overcome, in one way or another, the prevailing ruling classes who were tied to the older productive forces. Once the relations of production were radically altered, political, ideological, and cultural changes would follow. Marx concluded that all class societies, including capitalism, are transitory. Second, Marx investigated the production and circulation processes of industrial capitalism, from which he formulated a labor theory of value for analyzing the exploitation of workers by the capital-owning class. In this analysis, Marx found the origin of surplus value, the methods employed by capitalists to increase surplus value, and the role of the price system in redistributing the surplus value among capitalists. Marx concluded that the working class was bound to suffer impoverishment relative to the growing wealth around it, and, at times, absolutely. Third, Marx studied the processes of capital accumulation-that is, of investment, growth, and cycles-in capitalist societies. He showed that, during the accumulation process, there was a strong tendency for the rate of profit to fall and hence for the eventual retardation of capital accumulation. The ensuing recession restored the conditions required for another upswing, including the replenishment of the industrial reserve army of the unemployed and the strengthening of capital through mergers (centralization of capitals) and write-offs of redundant capital goods. Over the long run, according to Marx, the capital accumulation process created both wealth and poverty, it both drained and refilled the army of the unemployed, and it spawned both increasingly larger enterprises and a proliferation of small ones-the former comprising the monopoly sector and the latter a crowded and intensely competitive sector of small capitals. One of Marx's conclusions from these investigations was that periodic business cycles were endemic to capitalism, as natural and as inevitable as changes of the season; there was no remedy for them within the system of capitalism itself. The cycles were also functional for the (temporary) survival of the system. Fourth, one can find an economic theory of the state in Marx's writings. His researches led him to suppose, as I have just noted, that the state could not alleviate the commercial crises of capitalism, nor even the monetary panics which were but a phase of the broader crises. He was especially skeptical about financial policies as cures for what he took to be decennial cycles, although he did believe that certain budget and bank measures had temporary effects on economic activity-for example, easy money policies, he said, could keep the shopkeeping world in a good mood, presumably until the next crisis. On the other hand, the state could effectively intervene with economic legislation to support the capitalist class against any growing strength of workers, or to prevent the ruling class from destroying, through excessive *Stanford University, Stanford, CA 94305. I am indebted to Kenneth Arrow for valuable comments on an earlier draft.