Originally this was the process of transforming independent producers into wage-earning producers of surplus value. It was later expanded to include the integration into the proletariat of the middle strata of bourgeois society.
The proletarianization of the independent peasant and the tenant farmer
The main obstacle to the formation of a commodified society in which the vast majority of workers would live in urban centers and work no land at all was the extremely low productivity of pre-capitalist agriculture. That is why the conditions that make capitalism possible -and different from previous modes of production- must be sought in the countryside, not in the city. The process begins in 16th and 17th century England.
The bourgeoisie and the bourgeoisified aristocracy imposed two fundamental changes: the nationalization, enclosure and auctioning of communal lands, and the burden of property taxes, which drove the great landowners to raise the rents paid by their tenants.
The rise in land rents meant that, in the medium term, productivity had to be increased in order to be able to pay them. Deprived of the traditional "insurance" of the communal lands, the tenants either increased output per person employed or were evicted by the landlords. The increase in production would lower food prices and help feed the expropriated peasants, who would be forced either to work in the fields of the new tenants or to flee to the cities to sell their labor power.
The process pushes the surviving tenants to become capitalist farmers and compete against other capitalists by hiring desperate labor for starvation wages, or else to be forced off their holdings and work as proletarians.
This is the first proletarianization, which takes the inevitable form of rural misery and mass migration. The two main classes of capitalist society are being created out of the transformation of the feudal countryside. By the end of the 18th century almost half of the English population was already living in the cities as proletarians, ready to enter the industrial phase of capitalism. A proportion that other European countries, such as Spain, would not reach until the mid-1940s.
This process was repeated through "disentailments" wherever the bourgeoisie took power, and through the colonial administrations wherever the capitalist powers arrived as conquerors. Only in this way could capital escape from the "narrow base" of the strictly capitalist sphere and realize surplus value.
In this first moment, the proletarianization of the independent producer, or of the producer integrated into a previous mode of production (the day laborer, the guild apprentice, etc.), is merely formal: capital absorbs and exploits his labor but can only increase its profits by increasing absolute surplus value. Later, capital will transform that production from the bottom up, developing above all through the increase of relative surplus value, the dominant form in rising capitalism. This two-movement evolution is what Marx called the formal and real subsumption of labor under capital.
The proletarianization of the petty bourgeoisie
But the pressure toward proletarianization does not let up after that first blow. With every technological change, small and medium-sized capitals take advantage of the reduction in scale brought about by the increase in labor productivity to assert themselves. In doing so they open up a new branch, a whole new world of investment outlets for big capital, which will end up displacing or absorbing the small pioneer capitals and proletarianizing the small capitalists.
According to Marx, the mission of small capitals in the general march of capitalist development is to be the pioneers of technical advance, and this in two senses: by introducing new methods of production into already established branches of production and by creating new branches not yet exploited by big capital. It is completely false to believe that the history of the medium-sized capitalist enterprise is a straight line towards its gradual disappearance. On the contrary, the actual course of its development is purely dialectical and moves constantly among contradictions.
The capitalist middle strata, like the working class, are under the influence of two opposing tendencies, one that tends to raise them and another that tends to sink them. The downward tendency is the continuous increase in the scale of production, which periodically exceeds the dimensions of medium-sized capitals, repeatedly expelling them from the arena of world competition. The upward tendency is the periodic devaluation of existing capitals, which for a certain time lowers the scale of production, in proportion to the value of the minimum amount of capital required, and furthermore temporarily paralyses the penetration of capitalist production into new spheres.
The struggle between medium-sized enterprise and big capital should not be imagined as a periodic battle in which the weaker party sees the number of its troops diminish directly and ever further, but rather as a periodic mowing down of small enterprises, which rapidly spring up again only to be mown down once more by the scythe of big industry. The two tendencies play ball with the capitalist middle strata, but in the end the downward tendency triumphs, unlike what happens with the proletariat.
Rosa Luxemburg. Reform or Revolution, 1899
A new kind of machine enters the scene: the computer
At the beginning of the 1970s, capitalism enters into crisis. The postwar economic "boom" is over. Besides a whole series of changes in finance capital, a change in the productive model takes shape: a restructuring of employment in the central countries. Heavy industry, once the vital landscape of the stereotyped workers of political propaganda, is shipped overseas, dismantled reactor by reactor, smokestack by smokestack. If the steam engine meant the end of the artisans, now a new kind of machine enters the scene that will revolutionize capitalist production: the computer.
The exponential growth of computing power and telecommunications produced from the very beginning a great expansion of the service sector in the central countries. Personal stories abound of former car industry workers retrained as office employees after a brief course at a technical school or university. As some of these "retrained" employees recounted, conditions in the new job are better, but there is no organization and no class consciousness, and they risk being fired if they sound even remotely communist.
But it is not only a matter of retrained workers from classical industry, as happened in the past with the independent artisans. The "intellectual" professions, which had occupied the place of a "corporate petty bourgeoisie" by taking charge of the organization of labor within companies, the state or hospitals, were also being proletarianized: engineers, scientists, doctors, architects, journalists and other professionals become redundant. New software calculates, models and plans faster and more reliably than any engineer can.
The journalist's newspaper archive is three mouse clicks away, the scientist is reduced to pushing buttons on a PCR machine following standardized procedures: a process identical to that of the factory machines of yesteryear!
Capitalism is destroying one of the main divisions that hindered the affirmation of the universal class: the differentiation between manual and intellectual labor. The anachronistic fetishization of the manual worker of the last century makes no sense, simply because the exclusive identification of the proletariat with manual labor has no basis in the productive structure of present-day capitalism. In fact, we can say that the reductive identification of the proletariat with manual workers contributes nowadays to the general confusion and hinders the development of consciousness in a class that is ever more precarious, that is no longer called upon to produce in large factories, and most of whose members have never set foot in one.