Increased productivity and greater intensity of labor both have a similar effect. They both augment the mass of articles produced in a given time. Both therefore shorten that portion of the working day which the worker needs to produce his means of subsistence or their equivalent. The minimum length of the working day is fixed by this necessary component, which is however itself capable of further contraction. If the whole working day were to shrink to the length of its necessary component, surplus labor would vanish, something which is impossible under the regime of capital. Only the abolition of the capitalist form of production would permit the reduction of the working day to the necessary labor time. But even in that case the latter would expand to take up more of the day, and for two reasons: first, because the worker’s conditions of life would improve, and his aspirations become greater, and second, because a part of what is now surplus labor would then count as necessary labor, namely the labor which is necessary for the formation of a social fund for reserve and accumulation. The more the productivity of labor increases, the more the working day can be shortened, and the more the working day is shortened, the more the intensity of labor can increase. From the point of view of society the productivity of labor also grows when economies are made in its use. This implies not only economizing on the means of production, but also avoiding all useless labor. The capitalist mode of production, while it enforces economy in each individual business, also begets, by its anarchic system of competition, the most outrageous squandering of labor power and of the social means of production, not to mention the creation of a vast number of functions at present indispensable, but in themselves superfluous. The intensity and productivity of labor being given, the part of the social working day necessarily taken up with material production is shorter and, as a consequence, the time at society’s disposal for the free intellectual and social activity of the individual is greater, in proportion as work is more and more evenly divided among all the able-bodied members of society, and a social stratum is more and more deprived of the ability to shift the burden of labor (which is necessarily imposed by nature) from its own shoulders to those of another social stratum. The absolute minimum limit to the shortening of the working day is, from this point of view, the universality of labor. In capitalist society, free time is produced for one class by the conversion of the whole lifetime of the masses into labor time.
Karl Marx, “Changes of Magnitude in the Price of Labor Power”, in Capital, Vol. I, trans. by Ben Fowkes, New York: Penguin, 1990, pp. 666-667.








