This paper analyses how Cournot´s views on Monopoly have influenced the marginalists authors. It is argued that there are two different points of view in the cournotian evaluation of the consequence of Monopoly. The first one is a purely theoretical construction adopted in modern economic theory. Even if it is a theoretical one it has normative consequence. From these it is derived a negative appreciation on Monopoly. The second is a more pragmatic point of view. Whereas the former is purely theoretical the latter is derived from multiple examples and it cannot be based on the same theoretical framework as the well-known theory of monopoly prices. From this pragmatic point of view, Cournot constructs some positive appreciations on the existence of monopolies. These two different appreciations on imperfect markets have influenced in different ways the works of the authors of the Marginal Revolution. Following this distinction, we study the different points of view of Walras, Edgeworth and Marshall on Monopoly. We show that even if Walras´s theory of Monopoly does not have the same theoretical foundations of Cournot´s, his normative point of view on monopolies is closely related with the purely theoretical conclusions. Walras frequently quoted Cournot on these matters. Edgeworth and Marshall have a different point of view on Monopoly, mainly pragmatic and sometimes quite positive from the normative point of view. However, Walras´s as well as Edgeworth´s and Marshall´s theories on monopoly are not based on their theories of perfect competition. We conclude that the marginalists views on imperfect competition are not constructed as a perturbation or a friction of a perfectly competitive market.
