现实经济中存在着各种经济现象和经济过程。而经济现象的产生、变化和发展与经济过程的进程往往牵扯到许多因素。为了将复杂的问题简单化 ,研究者首先要将影响经济现象和经济过程的各种因素区分为本质因素和非本质因素 ,假定这些非本质因素不变或暂时撇开这些因素 ,使得分析简单化 ,然后 ,在此基础上进行复杂分析 ,最后得出某些理论结论。经济理论是在一定的假定条件下形成的 ,如果失去了这个条件 ,理论也就不适用了 ;如果对假定进行修改和变动 ,经济理论就会发生变化和发展。 In the real economy there are various economic phenomena and economic processes. However, the emergence, change and development of economic phenomena and the progress of economic processes often involve many factors. In order to simplify the complicated problems, the researchers must first distinguish the various factors that affect economic phenomena and economic processes into essential factors and non-essential factors. Assuming that these non-essential factors are invariable or temporarily excluding these factors, the analysis is simplified, Then, based on this complex analysis, and finally draw some theoretical conclusions. Economic theory is formed under certain assumptions. If this condition is lost, the theory does not apply. If the assumptions are modified and changed, the economic theory will change and develop.