A mode of production based on the commodification of human labor and its products, whose specific objective is the production of surplus value, that is, the extraction of surplus labor that generates an increase, in constant terms, in the mass of money returning to the balance sheet of the owners of capital at the end of each production cycle.
The particularities of capitalism compared to previous modes of production
Under capitalism the expropriation of the working class takes place by fundamentally economic means
Capitalism is the first mode of production in which the expropriation of the working class takes place by fundamentally economic means. It is not the armed exaction of the feudal lord or the use of violence by the state that directly expropriates part of the product of other people's labor.
On the contrary, it is the apparently free and generalized exchange of commodities that makes it possible to extract unpaid labor, in the form of surplus value, from the working class characteristic of this mode of production: the proletariat.
Of course, direct exaction still exists in many forms -through the state, for example- but it is neither the main source, nor the characteristic feature, nor the basis of the functioning of the system.
Capitalism is a system, not a social relation that can exist in isolation
Beneath the appearance of a complex system of voluntary exchanges, capitalism in reality conceals the appropriation of the unpaid labor of the workers as a whole by capital as a whole. It is not the sum of the results of exploitation company by company; it is a system: it requires an institutional framework that dominates the whole of society, turns human labor power into a commodity, forces the great majority to sell it freely on the market for goods and services in order to survive and, finally, allows capital to organize itself in a parallel capital market that distributes profits.
That is to say, there is no capitalism in a single company. And there is no capitalism without a capitalist state. That is why, even though there had been a bourgeoisie since the Middle Ages, capitalism did not begin until a series of revolutions in England, the USA and France gave state power to the bourgeoisie. The specifically capitalist function of the new state born then was to establish the social and legal relations that turned labor into the only commodity owned by the great mass of the population. Conditions that forced this new social class, the proletariat, to sell it voluntarily in order to survive.
Capitalism needs to develop the productive forces permanently
Like the ruling classes of the class-divided societies that preceded it, the bourgeoisie measures the success of its economy and its system -capitalism- by its ability to appropriate the product of social labor and direct it towards its own ends.
But unlike previous modes of production, capitalism tends continually to increase production and expand the market, to transform previous social relations into commodity relations, and to transform the means of production so as to enjoy a greater amount of social product.
The bourgeoisie cannot exist without constantly revolutionising the instruments of production, and thereby the relations of production, and with them the whole relations of society. Conservation of the old modes of production in unaltered form, was, on the contrary, the first condition of existence for all earlier industrial classes.
Constant revolutionising of production, uninterrupted disturbance of all social conditions, everlasting uncertainty and agitation distinguish the bourgeois epoch from all earlier ones. [...] The need of a constantly expanding market for its products chases the bourgeoisie over the entire surface of the globe. It must nestle everywhere, settle everywhere, establish connexions everywhere.
Karl Marx and Frederick Engels. Manifesto of the Communist Party, 1848
How capitalism turns the working class it creates into a universal class
This fundamentally economic, apparently automatic character of exploitation under capitalism means that the negation of the proletariat is total.
The proletariat itself is defined as the opposite of everything that characterizes society: in a society defined by the generalized exchange of commodities, it has no other commodity to sell than its own labor power; in a society whose ruling class groups itself and organizes society into national states, the proletariat has a universal condition that represents the dissolution of all nationalities.
Everything that defines human experience, everything that defines the human being under capitalism -commercial freedom, equality before the state, fraternity within the nation- is alien to it. Commercial freedom is, for the proletariat, wage slavery; equality before the state, its negation as a political class; national fraternity, the obligation to sacrifice itself for national capital in crises and wars.
Under capitalism, every need becomes subordinated to the needs of capital and is therefore universally denied in the proletariat.
Let us recall for a second the trade unionist who tells us that you cannot demand what the company's accounts cannot sustain without losses, the official who tells us that medical treatments or pensions must be subordinated to the deficit target, the leader who says that the borders cannot be opened to migrants looking for work because there is no capacity for employment, or the politician who tells us that he will not authorize lockdowns in the face of the pandemic because the economy is suffering...
...while the share of the value of national output devoted to paying capital income has been rising for sixty years, the hospitals of the ruling classes offer every existing treatment to anyone who can pay for it, the borders have always been open to capital and its managers, and the bourgeoisie all over the world lives confined in its fortress neighborhoods without that posing any problem at all.
It is from this total and universal negation that its main characteristic is born: it is a universal class, and not only because it exists worldwide, but because of the nature of the demands that appear in its struggles, even in their most limited forms: the proletariat fights for generic, universal human needs, not for privileges to exploit other social classes. That is why it is the revolutionary class of the capitalist mode of production. Only a universal class, exploited and universally oppressed and negated, can be the bearer of a program that in turn negates every form of exploitation, oppression or discrimination: communism.