The focus of Marx’s philosophical writings is alienation. He believes that social or psychological alienation arises out of economic or material alienation. In other words, consciousness is determined by material conditions, as opposed to the prevailing view of his day that said that consciousness determines material conditions. Another way of saying the same thing is, "Life is not determined by consciousness, but consciousness by life." One’s material conditions in life result from one’s labor. Concerning alienated labor, Marx said that,
...the worker is degraded to the most miserable sort of commodity; that the misery of the worker is in inverse proportion to the power and size of his production...

Marx sees the alienation of labor as return to feudalism, as is evidenced by his references to landlords and peasants in his writings about alienated labor. He sees this as the ultimate surrendering of the human spirit (in terms of social and psychological alienation) to the material alienation of capitalism. Furthermore, he sees it as a cycle that can and must be broken in order to allow us the full expression of our species essence, which he describes as communal.

Marx sees material alienation as the cause of social or psychological alienation. Material alienation he said is caused by the existence of private property. Private property came into existence through the (unequal) division of labor. Division of labor, therefore, is the central idea on which Marx bases his arguments concerning the eventual (inevitable) outcome of alienated labor.

Division of labor, in which the contradictions between the forces of production, the state of society, and consciousness are implicit because of the separation between intellectual and physical activity , according to Marx, began with the family. Marx sees the source of the division of labor as a result of the "natural division of labor in the family and the separation of society into individual families opposed to one another..." According to Marx,
The family, which to begin with is the only social relationship, becomes later, when increased needs create new social relations and the increased population new needs, a subordinate one..., and then must be treated and analysed according to the existing empirical data, not according to ‘the concept of family’...

The division of labor within the family resulted in the "unequal distribution, both quantitative and qualitative, of labor and its products..." which created the concept of private property. Wives and children were the "slaves of the husband," and therefore became the "first property."

Marx says that this "latent slavery in the family" corresponds precisely to the definition of the (then) modern economists who describe it as "the power of disposing of the labour-power of others." This means that the concept of private property relegates those whose labor is accordingly (unequally) divided to the status of slaves.

From this he goes on to state that, "Division of labor and private property are, moreover, identical expressions..." By this he means that the (unequal) division of labor affirms the (unequal) division of property. He also believes that because the mental and physical activities of laborers have been divorced, they (workers) have themselves become property. Specifically they have become the private property of industry, and are therefore no different, qualitatively and quantitatively in terms of access to resources and power, than slaves. Just as a slave is not free to decide whether or not to work on a given day, neither is the worker. Both must work in order to survive.

Marx states that, "...the division of labour implies the contradiction between the interest of the separate individual or the individual family and the communal interest of all individuals..." This communal interest is real, he says, and can be seen in the "mutual interdependence of the individuals among whom the labour is divided."

Carefully holding his argument together, Marx points out that, "...classes, already determined by the division of labour...," which form as a result of the contradiction between individual and communal interests, necessarily find themselves in a structure in which, "one dominates all the others."

This system, in which everyone is divided into various classes, with apparently contradictory interests, results according to Marx in a crisis of capitalism in which
...the necessary result of competition is the accumulation of capital in a few hands, and thus a more terrible