在读Meir Kohn的Macroeconomics。他在解释货币需求对经济运行的影响时说，Suppose that new banking regulation allows banks to begin paying interest on checking deposits. Then the holding of money more attractive. Households will increase their asset balances. This increase in the demand for money reduces domestic lending and so the supply of loanable funds. And this raises the interest rate, causing borrowing for investment to fall partly offsetting the decline in domestic lending.

我所不明白的是如果人持有更多的货币，那么银行应该有更多的存款，那就应该有更多lending，怎么反面少了。他解释说这是合成缪误，他说持有货币有利可图时，人们不只是会有更多的checking deposit，and an other effect is a decrease in total expenditure.他的解释是人的收入不变，当储蓄增加时，消费就一定要减少。As a result, even if you have more money in your checking deposit, others will have less in theirs. Net, the total amount of checking deposits in economy does not change.

我不明白，在经济学前提假设中，人是追求最优且理性的吗，经济中的每个人都应是一样的，怎么还有others。多谢！