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The paradox of thrift (or paradox of saving) is a paradox of economics. The paradox states that if everyone tries to save more money, then aggregate demand and therefore income will fall and will in turn lower ''total'' saving () in the population, because the tendency to save is directly related to the amount of income received. The paradox is, narrowly speaking, that total saving may fall even when individuals attempt to increase their saving, and, broadly speaking, that increase in saving may be harmful to an economy.〔These two formulations are given in Campbell R. McConnell (1960: 261–62), emphasis added: "By attempting to ''increase its rate of saving,'' society may create conditions under which the amount it can ''actually save'' is reduced. This phenomenon is called the paradox of thrift....()hrift, which has always been held in ''high esteem'' in our economy, now becomes something of a ''social vice.''"〕 Both the narrow and broad claims are paradoxical within the assumption underlying the fallacy of composition, namely that what is true of the parts must be true of the whole. The narrow claim transparently contradicts this assumption, and the broad one does so by implication, because while individual thrift is generally averred to be good for the economy, the paradox of thrift holds that collective thrift may be bad for the economy. It had been stated as early as 1714 in ''The Fable of the Bees,''〔Keynes, The General Theory of Employment, Interest and Money, (Chapter 23. Notes on Merchantilism, the Usury Laws, Stamped Money and Theories of Under-consumption )〕 and similar sentiments date to antiquity.〔See history section for further discussion.〕 It was popularized by John Maynard Keynes and is a central component of Keynesian economics. It has formed part of mainstream economics since the late 1940s. ==The paradox== The argument begins from the observation that in equilibrium, total income must equal total output. Assuming that income has a direct effect on saving, an increase in the autonomous component of saving, other things being equal, will move the equilibrium point at which income equals output to a lower value, thereby inducing a decline in saving that may more than offset the original increase. In this form it represents a prisoner's dilemma as saving is beneficial to each individual but deleterious to the general population. This is a "paradox" because it runs contrary to intuition. Someone unaware of the paradox of thrift would fall into a fallacy of composition and assume that what seems to be good for an individual within the economy will be good for the entire population. However, exercising thrift may be good for an individual by enabling that individual to save for a "rainy day", and yet not be good for the economy as a whole. This paradox can be explained by analyzing the place, and impact, of increased savings in an economy. If a population decides to save more money at all income levels, then total revenues for companies will decline. This decreased demand causes a contraction of output, giving employers and employees lower income. Eventually the population's total saving will have remained the same or even declined because of lower incomes and a weaker economy. This paradox is based on the proposition, put forth in Keynesian economics, that many economic downturns are demand-based. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Paradox of thrift」の詳細全文を読む スポンサード リンク
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