Abstract: The structure of scientific theories is an important issue in the philosophy of science， in which theoretic reductionism based on received views and emergentism based on Kuhns paradigm theory take distinct paths of scientific progress. By comparing the two views， this paper points out that neither mere reductionism nor mere emergentism can give an objective description of scientific development. A static analysis of the structure of scientific theories is not completely but partly reducible and a dynamic analysis of the revolution of scientific theories from the perspective of social history does take on an emergent characteristics; however， it is not completely but partly incommensurable between paradigms. It is suggested that the partly commensurability of paradigms can be explained by the corresponding rules of received views.

Key words: scientific theory, paradigm, received view, incommensurability, reduction, emergence