In the United States, the ratio of consumption to GDP has risen steadily over the past half century. In trying to understand why this ratio has increased so much, it is argued that standard models of the consumption function, built up from the neoclassical theory of constrained optimization, cannot offer a satisfactory answer. An alternative perspective is offered whereby aggregate consumption expenditure is seen as primarily the outcome of the population adopting widely upheld rules (‘meso-rules’) in a complex economic system. Aggregate consumption is viewed as the outcome of two contrasting historical processes: one mainly involving pre-committed, rule-bound choices and the other involving open-ended choices, made knowingly in the face of uncertainty, to adopt new meso-rules concerning the consumption of novel kinds of goods and services. The former process provides the degree of order that must be present in any complex system and the latter facilitates evolutionary change to occur. Using over half a century of data, the US consumption function is modelled successfully on the presumption that the economy is a complex system. The evidence supports the hypothesis that the ratio of consumption to GDP has risen because of the diffusion of a ‘culture of consumerism’ in the post-war era and that the limit of this process is now being approached, with important macroeconomic and social implications.

在美国，过去半个世纪中，消费与GDP的比率一直在稳步上升。在试图理解为什么该比率增加如此之多时，有人认为，根据约束优化的新古典理论建立的消费函数标准模型无法提供令人满意的答案。另一种观点是，总消费支出主要被视为人口在复杂的经济体系中采用广泛维护的规则（“中规”）的结果。总消费被认为是两个相反的历史过程的结果：一个主要涉及预先承诺的，有规则约束的选择，另一个涉及在不确定性的情况下有意识地做出的不限成员名额的选择，以采用有关消费的新的中观规则种新颖的商品和服务。前一个过程提供了任何复杂系统中必须存在的顺序程度，而后一个过程则促进了进化变化的发生。使用半个多世纪的数据，在经济是一个复杂系统的假设下，成功建立了美国的消费函数模型。证据支持这样的假设：由于战后时代的“消费主义文化”的传播，消费占GDP的比率已经上升，并且这一过程的局限性正在接近，并具有重要的宏观经济和社会意义。