西方尤其是美國，反托拉斯管制政策自立法以來迭有爭議，直至今日不同學派之間的看法依然呈現南轅北轍的風貌。一般傳統經濟學者認為應當多利用反托拉斯法，約束市場獨古廠商獨占力的濫用；芝加哥學派的學者，則主張除了卡特爾的行為或大型水平結合才需要予以關注外，其他的市場行為公權力的不介入是最適選擇。 本文以經濟理論「競爭」概念發展脈路，以及其衍生的研究方法和研究結果，解釋觀點不同學派的主張，發覺不同學派對反托拉斯管制看法的歧異，基本上源自於他們對「競爭」認知的不同。結構學派依據新古典理論完全競爭模型的「競爭」概念，發展出市場集中度勾結理論，和市場進入障礙的概念，主張反托拉斯管制的重點在於市場結構；相對的，師承古典經濟理論的芝加哥學派則主張敵對的「競爭」的概念，以為任何市場結構為市場競爭後的結果，它都是最有效率的組織，因此認為對市場結構管制的看法是不對的。可見經濟學界對反托拉斯管制觀點的不同，基本上是源自於他們接受「競爭」觀點的不同。

　　　　　Disputes have long existed in the U.S. since the pass of the Antitrust law. Scholars opinions are also divided on the issue. While most conventional economists are positive about the law in restraining firms monopolistic power, economists of the Chicago School oppose interventions on market operation exercised by governments except for a few cases, such as cartel, horizontal merger in immense magnitude, etc. This paper attempts to find out the fundamental distinction between the standpoints of economists, and to provide an explanation for their arguments. Based on our results, and to provide an explanation for their arguments. petition seems to be the source of the debates. The Structure School, admitting the concept of Neoclassical perfect competition, develops a doctrine of market concentration and a notion of barriers to entry. They think that market structure should be the focus of Antitrust enforement. In contrast, the Chicago School, recognizing the rival concept of competition from classical economic theory, emphasizes that market structure is the outcome rather than the cause of market competition. Therefore, it would not be appropriate to intervene the efficient form of market structure under most circumstances.