Capital, Volume Three: The Process of Capitalist Production as a Whole by Karl Marx

In the preceding part we demonstrated, among other things, that the rate of profit may vary – rise or fall – while the rate of surplus-value remains the same. In the present chapter we assume that the intensity of labor exploitation, and therefore the rate of surplus-value and the length of the working-day, are the same in all the spheres of production into which the social labor of a given country is divided. Adam Smith has already comprehensively shown that the numerous differences in the exploitation of labor in various spheres of production balance one another by means of all kinds of existing compensations, or compensations accepted as such on the basis of current prejudice, so that they are merely evanescent distinctions and are of no moment in a study of the general relations. Other differences, for instance those in the wage scale, rest largely on the difference between simple and complicated labor mentioned in the beginning of Book I (p. 19), and have nothing to do with the intensity of exploitation in the different spheres of production, although they render the lot of the laborer in those spheres very unequal. For instance, if the labor of a goldsmith is better paid than that of a day-laborer, the former's surplus-labor produces proportionately more surplus-value than the latter's. And although the equalizing of wages and working-days, and thereby of the rates of surplus-value, among different spheres of production, and even among different investments of capital in the same sphere of production, is checked by all kinds of local obstacles, it is nevertheless taking place more and more with the advance of capitalist production and the subordination of all economic conditions to this mode of production. The study of such frictions, while important to any special work on wages, may be dispensed with as incidental and irrelevant in a general analysis of capitalist production. In a general analysis of this kind it is usually always assumed that the actual conditions correspond to their conception, or, what is the same, that actual conditions are represented only to the extent that they are typical of their own general case.

The difference in the rates of surplus-value in different countries, and consequently the national differences in the degree of exploitation of labor, are immaterial for our present analysis. What we want to show in this part is precisely the way in which a general rate of profit takes shape in any given country. It is evident, however, that a comparison of the various national rates of profit requires only a collation of the previously studied with that which is here to be studied. First one should consider the differences in the national rates of surplus-value, and then, on the basis of these given rates, a comparison should be made of the differences in the national rates of profit. In so far as those differences are not due to differences in the national rates of surplus-value, they must be due to circumstances in which the surplus-value is assumed, just as in the analysis of this chapter, to be universally the same, i. e., constant.