In the history of American economy, the complex mixture, confusion and separation of the ideas of competition and monopoly are always found. Although the two forces are two basic extremes according to the economic theory, yet they are interwoven, with a variety of design, throughout the price system, each bearing to it a strong resemblance. In this paper, I have developed a special technique, apart from the traditional approach, to attack the problem of monopolistic competition with the precision of mathematical methods. The first step I will take, is to give a clear definition of the two fundamental forces of competition and monopoly, in the formulation of a theory of prices, and an examination of each in isolation. The second step must be a synthesis of the two. This brings back to the price theories of the two extreme channels, without the recognition of the middle course. Thirdly, I will try to evaluate the value under pure competition by distinguishing equilibrium from the equation of supply and demand; the individual sellers under pure competition and their cost curves and scales of production. Fourthly, I will attempt to analyze the present structure of duopoly and oligopoly. By doing this, I have managed to investigate and discover the mutual independence among the sellers; which finally lead to the effect of uncertainty.