Abstract: Says law, stated as “supply creates demand” by Keynes, has long been criticized by modern mainstream economics to be valueless theoretically and practically. However, supply and demand are dialectically interrelated in real economic world. Therefore, “creating something with no demands is equivalent to creating something with no value” is the very verity of Says law. If supply surplus exists in economy, it reflects the aimlessness of social production and will undermine macroeconomic growth and its sustainable development. Thus, in terms of the serious production surplus in certain fields of China economy, it is necessary to moderately expand aggregate demand and implement structuredreform strategy from the supply side.

Key words: supply, demand, Says law, Keyness law, supply side

摘要： 长期以来，凯恩斯表述为“供给创造需求”的萨伊定律受到现代主流经济学的批判，似乎萨伊定律没有任何理论和实践价值。但在现实经济活动中，供给和需求之间是相互联系的辩证关系。其中，“创造一种没有需求的东西就是创造一种无价值的东西”，体现出萨伊定律中的真理性。如果经济中存在着严重的供给过剩，这种反映社会生产盲目性的生产过剩势必拖累宏观经济和危害经济可持续发展。针对中国经济某些领域存在的严重生产过剩，在适度扩大总需求的同时，要实施供给侧结构性改革战略。

关键词: 供给, 需求, 萨伊定律, 凯恩斯定律, 供给侧