本文试图通过对Ontology这个古希腊以来西方哲学中的核心范畴的历史考证来揭示西学与中学在出发点上所存在的一个基本差异，即“是”与“应该”的差异，及其在中西学术和思想比较中的重要意义。一方面，“是”与“应该”的差异，构成了西学与中学几乎一切重大差异的根源；另一方面，这一思维方式在出发点上的差异也标志着中学和西方人文、社会科学学科在多数情况下属于两种不同类型的学问，二者之间在很多领域都不具有可比性。我们既不能以中学的标准来衡量西学，也不能以西学的标准来要求中学。无论是中学过去的分类体系，还是西学现在的分类体系都是在它们自身内在的思维理路的支配下逐步形成的，因而也都有着各自的合理性。 This article tries to reveal the basic difference between the west and the middle school on the starting point of Ontology, a historical study of the core categories of western philosophy since ancient Greece, that is, the difference between “yes” and “should”, and its difference between Chinese and Western academic and The significance of comparative thinking. On the one hand, the differences between “yes” and “should” constitute the root cause of almost all the major differences between western and middle schools. On the other hand, the difference in the starting point of this way of thinking also marks a gap between the middle schools and western humanities and social sciences In most cases, there are two different types of learning that are not comparable in many areas. We can neither measure Western learning by the standards of middle school nor the middle school by Western standards. Both the past classification system in middle schools and the classification system in western studies are gradually formed under the control of their own inner thinking and thus all have their own rationality.