The proletarian theory of capitalism is the concentration of all revolutionary innovations, with contributions by many, and Marx at the center pole. It is in constant development. Even Marx recognized his work as unfinished. In Das Kapital, he did not completely elaborate on a series of capitalism’s economic laws, but presented them as presuppositions, theorems or consequences of the production of surplus value and of the reproduction of social capital.
For example, the law of value is generally stated as a law of exchange of goods to their value, which corresponds to the socially necessary quantity of labor time required for their production. This formulation is based on the principle that the objective determination of the value of goods is realized by the labor time necessary for their production.
This formulation is not entirely correct; it is inexact, and it is the same argued by bourgeois economists, who have all been (like Marx) unable to scientifically develop it. So attempts have been made to explain value using other principles. One of these was by putting the problem into the context of mercantile circulation and basing the argument (an empirical argument to say the least) on a consequence of the mercantile circulation: competition. This leads to the theory of the tendency of the rate of profit to fall, from which some draw the erroneous conclusion that the demise of capitalism is inevitable.