The general conclusion at which I arrived and which, once reached, became the guiding principle of my studies can be summarised as follows.
In the social production of their existence, men inevitably enter into definite relations, which are independent of their will, namely relations of production appropriate to a given stage in the development of their material forces of production. The totality of these relations of production constitutes the economic structure of society, the real foundation, on which arises a legal and political superstructure and to which correspond definite forms of social consciousness. The mode of production of material life conditions the general process of social, political and intellectual life. It is not the consciousness of men that determines their existence, but their social existence that determines their consciousness. At a certain stage of development, the material productive forces of society come into conflict with the existing relations of production or – this merely expresses the same thing in legal terms – with the property relations within the framework of which they have operated hitherto. From forms of development of the productive forces these relations turn into their fetters. Then begins an era of social revolution. The changes in the economic foundation lead sooner or later to the transformation of the whole immense superstructure.
In studying such transformations it is always necessary to distinguish between the material transformation of the economic conditions of production, which can be determined with the precision of natural science, and the legal, political, religious, artistic or philosophic – in short, ideological forms in which men become conscious of this conflict and fight it out. Just as one does not judge an individual by what he thinks about himself, so one cannot judge such a period of transformation by its consciousness, but, on the contrary, this consciousness must be explained from the contradictions of material life, from the conflict existing between the social forces of production and the relations of production. No social order is ever destroyed before all the productive forces for which it is sufficient have been developed, and new superior relations of production never replace older ones before the material conditions for their existence have matured within the framework of the old society.
Mankind thus inevitably sets itself only such tasks as it is able to solve, since closer examination will always show that the problem itself arises only when the material conditions for its solution are already present or at least in the course of formation. In broad outline, the Asiatic, ancient, [A] feudal and modern bourgeois modes of production may be designated as epochs marking progress in the economic development of society. The bourgeois mode of production is the last antagonistic form of the social process of production – antagonistic not in the sense of individual antagonism but of an antagonism that emanates from the individuals' social conditions of existence – but the productive forces developing within bourgeois society create also the material conditions for a solution of this antagonism. The prehistory of human society accordingly closes with this social formation. — Emphasis added.
In contemporary terms, Marx is asserting that microfoundations based on individualism is ill-conceived given (assuming) the "guiding principle" at which his previous research had arrived: "It is not the consciousness of men that determines their existence, but their social existence that determines their consciousness."
This is a rejection of homo economicus in favor of homo socialis, as well as a rejection of methodological individualism based on ontological individualism in social, political and economic methodology. This is consistent with Aristotle's position in Politics, as Marx would have known:
From these things therefore it is clear that the city-state is a natural growth, and that man is by nature a political animal [ho anthropos physei politikon zoon], and a man that is by nature and not merely by fortune citiless is either low in the scale of humanity or above it (like the “ clanless, lawless, heartless ” man reviled by Homer,1 for one by nature unsocial is also ‘a lover of war’）inasmuch as he is solitary, like an isolated piece at draughts. — Politics, Book I, 1253aHowever, Marx also implicitly rejects Aristotle's political institutionalism based on civil law as basic in favor of a socio-economic mode of production as foundational. For Marx, social and political superstructure is based on economic infrastructure.
This dovetails with Darwin's natural selection as the driver of survival of the fittest. Since Darwin's On the Origin of Species was published in the same year (1859) as Marx's A Contribution to the Critique of Political Economy, Marx would not be reacting to Darwin in this work. However, Marx was well read in history and his work is historically based rather than theoretical.
For Marx, subsistence is bottom line and it necessarily precedes surplus production since subsistence living is required for survival as an individual in a group, humans not being lone hunters. Among primitive people, subsistence living as determined by a particular environment was the starting point from which human development emerged through language (communications) and tool use (technology).
Everything we call "human" — culture, institutions, etc, — is based first on surviving in a challenging environment and then prospering by creating a surplus if possible. Then the question becomes how to divide the surplus over subsistence in a group. Historically, that has devolved to power relationships based on relations among subgroups within a group. This alignment based on economic infrastructure determines cultural and institutional superstructure.
Why did Marx pursue this approach since he was educated in classical thought and had a PhD philosophy, having written a dissertation on Greek atomism. On one had, he was interested in an evidence-based theory in the newly developing scientific age. He was a harbinger of sociology, for example, if he is not considered one of the founders of the discipline. Das Kapital is a work in political economy and economic sociology rather than theoretical economics, which had not yet appeared on the scene.
One the other hand, Marx was born into tumultuous times in Europe, after the French Revolution and its aftermath. Marx does not come out of nowhere. He was intensely involved in the issues of the day and was reacting to the many influences that were au courant.
While Marx was a man of his time and would almost certainly have adapted his thinking to new knowledge and changing circumstance given the development of his thought, his analysis still speaks powerfully today in many important respects that conventional economics and political theory have not only ignored but also suppressed in the West. His work has influenced sociology however and continues to do so through class and power.
Now it is past time to revisit Marx's ideas about the foundational nature of social modes of production as humanity stands on the cusp of a transition from the Industrial Age to the Information Age, which is proving as profound and transformative as the transition from the Agricultural Age to the Industrial age and from the Hunter-Gather the Agricultural.
While Marx could not have dreamed of the advances in communications and technology, let alone foreseen them, many of his insights are remain vibrant, such as the foundation importance of the mode of production. What will be the outcomes of the present transformation owing to the digitizing of the means of production?
Karl MarxPreface to A Contribution to the Critique of Political Economy (1859)