Karl Marx, answered from the texts and cited to the page.
The forces of production are the actual material and human powers through which a society transforms nature into the means of its existence. They are not merely tools or machines in isolation, but the entire complex: the laboring subject with her developed capacities, the instruments she uses, the raw materials she works upon, and — crucially — the forms of social cooperation through which individual labor becomes collective productive power.
The community itself is the first great force of production.1 Before machinery, before the division of labor in its developed form, the clan or commune organized as a productive unit already represents a force — the combination of individual efforts into something no single person could accomplish. Particular conditions of production, stock-breeding or agriculture, then develop particular modes of working and particular forces, both objective ones (tools, land, instruments) and subjective ones that appear as qualities of the individuals themselves: skill, knowledge, the accumulated practical intelligence of generations.2
What capital does to this picture is both develop the forces and invert their relation to the living laborer. Co-operation, manufacture, the factory organized on the basis of machinery — all these are forms of socially developed labor, and therefore genuine expansions of productive power.3 But under the capitalist mode of production they confront the individual laborer as something extraneous and objective, as functions of capital rather than as powers of the associated producers themselves.4
The means of production do not appear as subsumed to the laborer; the laborer appears as subsumed to them — he does not make use of them, but they make use of him.5 This is the inversion: the productive powers of social labor appear as the productive powers of capital, of materialized labor standing over living labor, of the worker's own product confronting him as an alien force.6
The development of the forces of production is also uneven and subject to natural limits — productivity in one branch advances while another retrogresses, natural conditions (forests, coal seams, soil fertility) are exhausted even as social productivity rises, and the rate of average profit falls considerably below what the most advanced lines of industry might suggest.7
The forces of production are not a smooth upward march; they develop under the specific relations of production that both enable and constrain them, until those relations turn from forms of development into fetters. Then the epoch of social revolution begins — not as moral preference, but as the structural consequence of what the productive forces have outgrown.
The community itself appears as the first great force of production; particular kinds of production conditions (e.g. stock-breeding, agriculture), develop particular modes of production and particular forces of production, subjective, appearing as qualities of individuals, as well as objective [ones].Grundrisse, pp. 418–419
particular kinds of production conditions (e.g. stock-breeding, agriculture), develop particular modes of production and particular forces of production, subjective, appearing as qualities of individuals, as well as objective [ones].Grundrisse, pp. 418–419
the forms of socially developed labour—co-operation, manufacture (as a form of division of labour), the factory (as a form of social labour organised on machinery as its material basis)—all these appear as forms of the development of capital, and therefore the productive powers of labour built up on these forms of social labour—consequently also science and the forces of nature—appear as productive powers of capital.Theories of Surplus Value Vol I, pp. 388–389
all this confronts the individual labourers themselves as something extraneous and objective, as a mere form of existence of the means of labour that are independent of them and control them.Theories of Surplus Value Vol I, pp. 388–389
He does not make use of them, but they make use of him. And it is this that makes them capital.Theories of Surplus Value Vol I, pp. 387–388
Since living labour—through the exchange between capital and labourer—is incorporated in capital, and appears as an activity belonging to capital from the moment that the labour-process begins, all the productive powers of social labour appear as the productive powers of capital.Theories of Surplus Value Vol I, pp. 387–388
the development of the productive forces in different lines of industry proceeds in considerably different rates, or even in opposite directions, is not due merely to the anarchy of competition and the peculiarity of the bourgeois mode of production. The productivity of labor is also conditioned on natural premises, which frequently become less productive to the extent that productivity, so far as it depends on social conditions, increases.Capital Vol III