预期、集聚的动态演化与政策：基于文献的讨论

政府干预在集聚经济中的作用一直是新经济地理学研究的薄弱环节，通过引入预期概念，可将政府行为内生化为个人或企业微观决策即要素空间流动的重要动因，进而完善新经济地理学的分析框架，尤其是增强其对属于后发型的、非完全市场经济的我国产业集聚分析的解释力。既有的新经济地理学理论通过对市场主体的区位选择进行一般均衡分析，揭示了集聚产生的内生机制，认为基于微观经济主体自发行为的要素流动是集聚产生并强化的关键因素之一。然而，大部分新经济地理学分析假设经济主体是短视而被动的，这与现实中要素流动大多是基于预期下的优化选择行为具有较大反差，经济主体并非被动地根据区域间当前的效用差异进行决策。预期分析与新经济地理学分析的融合，完善了空间宏观异质性形成的微观基础，揭示了预期对集聚的形成及其动态变化有着重要的影响。此外，政策可以通过影响个体预期内生于个体经济行为和集聚过程，从而证明政府通过政策引导集聚是可行的。

Forward-looking Expectations，Dynamic Evolution of Agglomeration and Policy:A Literature-based Discussion

As a widespread way of optimizing resource allocation， the interregional flowing of economic factors is the micro foundation of the formation of agglomerations or that of cities. Based on a general equilibrium analysis of economic agents' location choices， new economic geography attractively reveals the endogenous mechanism of agglomeration， showing that factor flowing based on microeconomic spontaneous behavior is the key to generate and strengthen the agglomerations. However， much of the new economic geography literature assumes myopic economic agents， that is， the economic agents are assumed to ignore the future， basing their migration choices on current wage differences alone. This is not consistent with the rational expectations and forward-looking optimizing behavior of economic agents in the reality. In fact， factor flowing involves cost. Economic agents are interested not only in currently available returns but also in the returns they expect in the future. The role of expectations turns out to be crucial in their decisions for migration. This paper reviews the literature integrating the behavior of rational forward-looking theory with the new economic geography analysis. We find that by modifying the basic micro-foundation hypothesis of macro-heterogeneity， i.e. factor mobility rules， the new economic geography with forward-looking expectations shows that forward-looking expectations have an impact on the evolution of agglomerations. On the one hand， the migration decisions of forward-looking agents directly influence where the economic elements flow and thus where the agglomerations would emerge. On the other hand， the inclusion of forward-looking behavior partially affects the long-term stability of local stable equilibria in the new economic geography as ad hoc myopic adjustment is replaced by full-fledged forward-looking dynamics. Whether the expectations (initial beliefs) as opposed to history （initial endowments） matter for the long-run spatial distribution of economic activities depends on how much agents care about the future， the parameter values of trade cost and factor mobility as well. It is worth noting that under certain circumstances expectations can weaken， even reverse， the lock-in effect of the historically-inherited size advantage of the bigger regions， which is revealing to the study on the spatial agglomeration of economic activities in China characterized by strong government intervention during our transformation from planned economy to market economy. A policy can be an endogenous driving force of individual economic behavior by affecting the individual expectations. It can be a forceful agent to realize agglomerations in certain areas by ″self-fulfilling expectations. ″At the same time， government policies have a limited impact on the economic system. Whether the impact can turn into an endogenous driving force of agglomeration and be adopted by the system depends on the law of agglomeration as well. That is， in an economic system affected by government behavior， the formation and development of agglomerations depend on the effective interplay of market mechanism and government policies.  The integration of forward-looking expectations with the new economic geography analysis reinforces people's subjective initiative in economic activities. Theoretically， the new economic geography incorporating forward-looking agents perfects the micro-foundation hypothesis of macroscopic heterogeneity in space. It shows that economic agents are not passively reactive to economic circumstance|rather， they exert influence on the future economic system by forward-looking expectations. Methodically， it extends a two-dimensional perspective of ″micro-space″ to a three-dimensional research perspective of ″micro-space-time,″ exhibiting a full-fledged dynamics analysis partially replacing ad hoc dynamics. Furthermore，adding forward-looking expectations into new economic geography does enrich the theory by incorporating government policy as an endogenous driving force of agglomeration. It is helpful for a better understanding of the evolution of agglomerations with government intervention in China， a country with an imperfect economic system．  The highlight of this paper is that it is the first to review relevant studies on the new economic geography incorporating forward-looking expectations. Based on that， it summarizes how expectation works on the evolution of the agglomeration in China characterized by government intervention， in particular， how expectation makes it possible to turn government policies into an endogenous force of agglomeration. Thus， the paper perfects the explanatory power of new economic geography in analyzing the agglomeration in an incomplete market economy. This has significant implications for the evolution of our government-directed industrial agglomeration．