Overlapping generations: Kicking the can down an endless road 代代叠加："拖"无止境

　　The final brief in our series on big economic ideas looks at the costs (and benefits) of passing on the bill to the next generation. 我们的重大经济思想的最后一篇考察的是寅吃卯粮的代价（和好处）。

　　In the spring of 1899 William Miller persuaded three members of his Brooklyn prayer group to invest their money with him, promising them unearthly returns. 1899年春，威廉·米勒（William Miller）说服了他在布鲁克林祈祷小组的三位成员把钱交给他来投资，向他们承诺了异乎寻常的回报。

　　He would pay a dividend of 10% per week, plus a commission for each new investor they could recruit. 他会每周支付10%的红利，外加真对他们可能招募来的每一位新投资者的一份佣金。

　　Soon, William “520%” Miller was drawing throngs of depositors to his door. 不久，威廉·520%·米勒吸引了大批存款人上门。

　　So “great was the crush”, by one account, his staircase eventually gave way. 据称，当时人群汹涌，以至于他的楼梯最后都被挤塌了。

　　Miller attributed his success to “inside information”. 米勒认为，他的成功归功于“内幕消息”。

　　But his real method was made famous 20 years later by the man who perfected it, Charles Ponzi. 但是，他真正的方法是在20年后是因为那位使之完美无瑕的人——查尔斯·庞兹（Charles Ponzi）而闻名天下的。

　　Ponzi schemes like Miller's pay a return to early investors with money raised from later ones. 庞氏骗局（Ponzi schemes）同米勒用从后来者那里筹集到的钱支付早先的投资者的方式如出一辙。

　　When they run short of new contributions, they collapse. 当缺少新的出资时，它们就崩溃了。

　　A scheme as generous as Miller's cannot last long. 如米勒般慷慨的骗局无法持久。

　　But what if the promises were less extravagant and the repayment intervals less tight? 但是，如果承诺少一些夸大，偿还间隔不是那么近呢？

　　What if, for example, a scheme asked investors for money in their younger years in return for a payout in their dotage? 例如，如果骗局在投资者年轻时向他伸手要钱，在年老体衰时报之以偿还呢？

　　Over that time scale, a Ponzi scheme need not limit its recruitment efforts to the people alive when it begins. 在这段时间内，庞氏骗局不需要对在它们开始时活着的人的招募努力加以限制。

　　It can repay today's contributors with money from future participants not yet born. 它可以用来自尚未出生的未来参与者的钱偿还今天的出资者。

　　And since the next generation is never likely to be the last, the chain could, in principle, continue indefinitely. 而且，由于下一代永远不可能是最后的一代，从理论上说，这一链条可以无限期地继续下去。

　　Barring a catastrophe, new marks will be born every day. 除非天灾人祸，每一天都会有新生命出生。

　　This intergenerational logic lies behind the “pay-as-you-go” (PAYG) pensions common in many countries. 这种存在与现收现付养老金（pay-as-you-go 简称PAYG）背后的代际逻辑，在许多国家都是很常见的。

　　People contribute to the scheme during their working lives, and receive a payout in retirement. 人们在自己的工作之年给骗局出资，在退休时拿到偿付。

　　Many people fondly imagine that their contributions are saved or invested on their behalf, until they reach pensionable age. 许多人天真地假设，他们的出资要么是被存了起来，要么是以他们的名义被投了出去，直到他们达到可以领养老金的年纪。

　　But that is not the case. 但是，情况并非如此。

　　The contributions of today's workers pay the pensions of today's retirees. 当今工人的出资偿付的是当今退休人员的养老金。

　　The money is transferred between generations, not across time. 钱是在几代人之间转来转去，并没有跨越时间。