中文摘要
现代宏观经济学忽视了近来新型货币的大量涌现。我们在模型中表明,信用卡、稳定币、加密货币或直升机货币等新型货币可能引发价格的大幅上涨,就像20世纪70年代信用卡全面投入使用时出现的通货膨胀。这些货币并非完全替代品,因此通过收缩传统货币供给来抵消新型货币的增长会带来福利成本。价格水平由追逐商品的货币决定,并以各类货币各自的数量以及个体交易规模来度量。在第一部分,我们给出模型的单期版本,聚焦于货币的交易职能。我们证明,若存在足够的交易收益,法币财富(扣除税收后的净额)可以为正。提高法币财富的货币(如直升机货币)会通过提高利率引发更多通货膨胀——最终甚至引发恶性通货膨胀——而利率上升会减少交易。相比之下,信用卡(以及中央银行购买债券)同样会引发通货膨胀,但它们能增进交易与福利。在第二部分,我们给出模型的多期版本,其中货币的价值储藏职能以及关于未来政策的预期也会影响通货膨胀。
Abstract
ABSTRACT Modern macroeconomics ignores the recent proliferation of new monies. We show in our model that new monies like credit cards or stable coins or crypto currencies or helicopter money can cause a huge increase in prices, like the 1970s inflation when credit cards emerged in full use. These monies are not perfect substitutes, so shrinking conventional money supply to compensate for the growth of new monies comes at a welfare cost. Price levels are determined by money chasing goods, measured by the separate quantities of each kind of money and the scale of individual transactions. In Part I we introduce a one period version of our model in which we concentrate on the transactions role of monies. We show how fiat wealth (net of taxes) can be positive if there are enough gains to trade. Monies that raise fiat wealth (such as helicopter money) cause more inflation—eventually even hyperinflation—by increasing the interest rate, which reduces transactions. In contrast, credit cards (and central bank purchases of bonds) also cause inflation, but they enhance transactions and welfare. In Part II we present a multiperiod version in which the store‐of‐value role of money, and expectations about future policy, also affect inflation.