是经济多样性或是产业专业化更有利于技术创新和城市增长是近几年来学界争论的问题。传统的研究方法,多利用经济分类(包括标准产业分类和专利分类)数据来探究产业构成与知识溢出和经济增长之间的因果关系,但这种方法并不能清晰地说明不同环境下知识溢出的具体过程,从而对有关争论无法给出令人信服的结论。本文通过比较人造事物与自然生物的演化差异,发现人类创造力的特性与技术创新的本质在于把现有的、以前不相关的资源或技术进行有效的组合。虽然专业化城市在特定城市体系中也能够促进技术创新及经济增长,但从单体城市的层面看,产业多样性较专业化不仅有利于各种不相关的事物的组合,而且还能提供创新者所需的企业家精神氛围和更大的集聚经济,因此更利于城市的长期增长。

Recent literatures on urban growth have been stressing on the role of technological innovation and spillovers in generating economic growth. Due to the shortage of convincing explorations, tradiional empirical approaches, using the economic classification data to measure technological learning, have some limitation and shortcomings in the study on the relationship between the regional setting and urban growth, and cannot explain the concrete course of the knowledge spillover under the differrent environments. Based on the analysis of Jacob's externalities and the general process of technological innovation, this paper, first, finds out that the characteristics of human creativity and the essence of technological innovation are resulted from the effective combination of the existing, previously unrelated resources or technologies, and the key of technological innovation in the micro level is on the issue how knowledge is actually created and exchanged. Then, the paper probes how knowledge is actually created and exchanged by individuals and how technology is combined through human action and creative uses of resources. The paper holds that the reasons why industry diversity is more beneficial to urban growth than economic specialization can be effectively explained by the more opportunities to combine those heterogeneous resources and technologies. Finally, taking Pittsburgh in the United States as an example, this paper analyses the different effects of the industrial specialization and the diversity on urban growth. It is concluded that the economic diversity is not only more favorable to the combination of different unrelated things, but also can offer more necessary and beneficial settings to inspire the entrepreneurship and the greater agglomeration economy. So the economic diversity other than the industry specialization is more helpful for a city to approach its technological innovation and long-term growth, and the role of industry specialization for urban growth should not be overvalued.