Influences on Karl Marx are commonly referred to as deriving from three sources: German idealist philosophy, French socialism, and English & Scottish political economy. Although this "three sources" model is an oversimplification, it still has some measure of truth.

German philosophy

Immanuel Kant
Immanuel Kant is believed to have had the greatest influence of any philosopher of modern times. Kantian philosophy was the basis on which the structure of Marxism was built - particularly as it was developed by Georg Hegel. Hegel's dialectical method, which was taken up by Karl Marx, was an extension of the method of reasoning by “antinomies” that Kant used. [1]

Georg Hegel
Georg Hegel, by the time of his death, was the most prominent philosopher in Germany. His views were widely taught, and his students were highly regarded. His followers soon divided into right-wing and left-wing Hegelians. Theologically and politically the right-wing Hegelians offered a conservative interpretation of his work. They emphasized the compatibility between Hegel's philosophy and Christianity. Politically, they were orthodox. The left-wing Hegelians eventually moved to an atheistic position. In politics, many of them became revolutionaries. This historically important left-wing group included Ludwig Feuerbach, Bruno Bauer, Friedrich Engels, and Marx. [2] They were often referred to as the Young Hegelians.

Marx's view of history, which came to be called historical materialism, is certainly influenced by Hegel's claim that reality (and history) should be viewed dialectically. Hegel believed that the direction of human history is characterized in the movement from the fragmentary toward the complete and the real (which was also a movement towards greater and greater rationality). Sometimes, Hegel explained, this progressive unfolding of the Absolute involves gradual, evolutionary accretion but at other times requires discontinuous, revolutionary leaps — episodal upheavals against the existing status quo. For example, Hegel strongly opposed slavery in the United States during his lifetime, and he envisioned a time when Christian nations would radically eliminate it from their civilization.

While Marx accepted this broad conception of history, Hegel was an idealist, and Marx sought to rewrite dialectics in materialist terms. He summarized the materialistic aspect of his theory of history in the 1859 preface to A Contribution to the Critique of Political Economy:

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.

In this brief popularization of his ideas, Marx emphasized that social development sprang from the inherent contradictions within material life and the social superstructure. This notion is often understood as a simple historical narrative: primitive communism had developed into slave states. Slave states had developed into feudal societies. Those societies in turn became capitalist states, and those states would be overthrown by the self-conscious portion of their working-class, or proletariat, creating the conditions for socialism and, ultimately, a higher form of communism than that with which the whole process began. Marx illustrated his ideas most prominently by the development of capitalism from feudalism, and by the prediction of the development of socialism from capitalism.

Ludwig Feuerbach
See also: Ludwig Feuerbach and Marx's theory of alienation
Ludwig Feuerbach was a German philosopher and anthropologist. According to Feuerbach, social and political thought should take as their foundation people and their material needs. He held that an individual is the product of their environment, that the whole consciousness of a person is the result of the interaction of sensory organs and the external world. Marx (and Engels) saw in Feuerbach's emphasis on people and human needs a movement toward a materialistic interpretation of society. [3]

In The Essence of Christianity, Feuerbach argued that God is really a creation of man and that the qualities people attribute to God are really qualities of humanity. Accordingly, Marx argued that it is the material world that is real and that our ideas of it are consequences, not causes, of the world. Thus, like Hegel and other philosophers, Marx distinguished between appearances and reality. However he did not believe that the material world hides from us the "real" world of the ideal; on the contrary, he thought that historically and socially specific ideology prevented people from seeing the material conditions of their lives clearly.

What distinguished Marx from Feuerbach was his view of Feuerbach's humanism as excessively abstract, and so no less ahistorical and idealist than what it purported to replace, namely the reified notion of God found in institutional Christianity that legitimized the repressive power of the Prussian state. Instead, Marx aspired to give ontological priority to what he called the "real life process" of real human beings, as he and Engels said in The German Ideology (1846):

In direct contrast to German philosophy, which descends from heaven to earth, here we ascend from earth to heaven. That is to say, we do not set out from what men say, imagine, conceive, nor from men as narrated, thought of, imagined, conceived, in order to arrive at men in the flesh. We set out from real, active men, and on the basis of their real life process we demonstrate the development of the ideological reflexes and echoes of this life process. The phantoms formed in the human brain are also, necessarily, sublimates of their material life process, which is empirically verifiable and bound to material premises. Morality, religion, metaphysics, all the rest of ideology and their corresponding forms of consciousness, thus no longer retain the semblance of independence. They have no history, no development; but men, developing their material production and their material intercourse, alter, along with this, their real existence, their thinking, and the products of their thinking. Life is not determined by consciousness, but consciousness by life.

Also, in his Theses on Feuerbach (1845), he writes that "the philosophers have only described the world, in various ways, the point is to change it". This opposition between, firstly, various subjective interpretations given by philosophers, which may be, in a sense, compared with Weltanschauung designed to legitimize the current state of affairs, and, secondly, the effective transformation of the world through praxis, which combines theory and practice in a materialist way, is what distinguishes "Marxist philosophers" from the rest of philosophers. Indeed, Marx's break with German Idealism involves a new definition of philosophy; Louis Althusser, founder of "Structural Marxism" in the 1960s, would define it as "class struggle in theory". Marx's movement away from university philosophy and towards the workers' movement is thus inextricably linked to his rupture with his earlier writings, which pushed Marxist commentators to speak of a "young Marx" and a "mature Marx", although the nature of this cut poses problems. A year before the Revolutions of 1848, Marx and Engels thus wrote The Communist Manifesto, which was prepared to an imminent revolution, and ended with the famous cry: "Proletarians of all countries, unite!". However, Marx's thought changed again following Louis-Napoleon Bonaparte's December 2, 1851 coup, which put an end to the French Second Republic and created the Second Empire which would last until the 1870 Franco-Prussian War. Marx thereby modified his theory of alienation exposed in the Economic and Philosophical Manuscripts of 1844 and would latter arrive to his theory of commodity fetishism, exposed in the first chapter of the first book of Das Kapital (1867). This abandonment of the early theory of alienation would be amply discussed, several Marxist theorists, including Marxist humanists such as the Praxis School, would return to it. Others, such as Althusser, would claim that the "epistemological break" between the "young Marx" and the "mature Marx" was such that no comparisons could be done between both works, marking a shift to a "scientific theory" of society.

The rupture with German Idealism and the Young Hegelians
Marx did not study directly with Hegel, but after Hegel died Marx studied under one of Hegel's pupils, Bruno Bauer, a leader of the circle of Young Hegelians to whom Marx attached himself. However, Marx and Engels came to disagree with Bruno Bauer and the rest of the Young Hegelians about socialism and also about the usage of Hegel's dialectic. From 1841, the young Marx progressively broke away from German idealism and the Young Hegelians. Along with Engels, who observed the Chartist movement in the United Kingdom, he cut away with the environment in which he grew up and encountered the proletariat in France and Germany.

He then wrote a scathing criticism of the Young Hegelians in two books, "The Holy Family" (1845), and The German Ideology (1845), in which he criticized not only Bauer but also Max Stirner's The Ego and Its Own (1844), considered as one of the founding book of individualist anarchism. Max Stirner claimed that all ideals were inherently alienating, and that replacing God by the Humanity, as did Ludwig Feuerbach in The Essence of Christianity (1841), was not sufficient. According to Stirner, any ideals, God, Humanity, the Nation, or even the Revolution alienated the "Ego". Marx also criticized Proudhon, whom had became famous with his cry "Property is theft!", in The Poverty of Philosophy (1845).

Marx's early writings are thus a response towards Hegel, German Idealism and a break with the rest of the Young Hegelians. Marx, "stood Hegel on his head," in his own view of his role, by turning the idealistic dialectic into a materialistic one, in proposing that material circumstances shape ideas, instead of the other way around. In this, Marx was following the lead of Feuerbach. His theory of alienation, developed in the Economic and Philosophical Manuscripts of 1844 (published in 1932), inspired itself from Feuerbach's critique of the alienation of Man in God through the objectivation of all his inherent characteristics (thus man projected on God all qualities which are in fact man's own quality which defines the "human nature"). But Marx also criticized Feuerbach for being insufficiently materialistic, as Stirner himself had point out, and explained that the alienation described by the Young Hegelians was in fact the result of the structure of the economy itself. Furthermore, he criticized Feuerbach's conception of human nature in his sixth thesis on Feuerbach as an abstract "kind" which incarnated itself in each singular individual: "Feuerbach resolves the essence of religion into the essence of man (menschliche Wesen, human nature). But the essence of man is no abstraction inherent in each single individual. In reality, it is the ensemble of the social relations." Thereupon, instead of founding itself on the singular, concrete individual subject, as did classic philosophy, including contractualism (Hobbes, Locke and Rousseau) but also political economy, Marx began with the totality of social relations: labour, language and all which constitute our human existence. He claimed that individualism was an essence the result of commodity fetishism or alienation. Although some critics have claimed that meant that Marx enforced a strict social determinism which destroyed the possibility of free will, Marx's philosophy in no way can be reduced to such determinism, as his own personal trajectory makes clear.

In 1844-5, when Marx was starting to settle his account with Hegel and the Young Hegelians in his writings, he critiqued the Young Hegelians for limiting the horizon of their critique to religion and not taking up the critique of the state and civil society as paramount. Indeed in 1844, by the look of Marx's writings in that period (most famous of which is the "Economic and Philosophical Manuscripts of 1844", a text that most explicitly elaborated his theory of alienation), Marx's thinking could have taken at least three possible courses: the study of law, religion, and the state; the study of natural philosophy; and the study of political economy. He chose the last as the predominant focus of his studies for the rest of his life, largely on account of his previous experience as the editor of the newspaper Rheinische Zeitung on whose pages he fought for freedom of expression against Prussian censorship and made a rather idealist, legal defense for the Moselle peasants' customary right of collecting wood in the forest (this right was at the point of being criminalized and privatized by the state). It was Marx's inability to penetrate beneath the legal and polemical surface of the latter issue to its materialist, economic, and social roots that prompted him to critically study political economy.

English and Scottish political economy
Political economy predates the 20th century division of the two disciplines of politics and economics, treating social relations and economic relations as interwoven. Marx built on and critiqued the most well-known political economists of his day, the British classical political economists.

Adam Smith and David Ricardo
From Adam Smith came the idea that the grounds of property is labour.

Marx critiqued Smith and Ricardo for not realizing that their economic concepts reflected specifically capitalist institutions, not innate natural properties of human society, and could not be applied unchanged to all societies. He proposed a systematic correlation between labour-values and money prices. He claimed that the source of profits under capitalism is value added by workers not paid out in wages. This mechanism operated through the distinction between "labour power", which workers freely exchanged for their wages, and "labour", over which asset-holding capitalists thereby gained control.

This practical and theoretical distinction was Marx's primary insight, and allowed him to develop the concept of "surplus value", which distinguished his works from that of Adam Smith and David Ricardo. Workers create enough value during a short period of the working day to pay their wages for that day (necessary labour); however, they continue to work for several more hours and continue to create value (surplus labour). This value is not returned to them but appropriated by the capitalists. Thus, it is not the capitalist ruling class that creates wealth, but the workers, the capitalists then appropriating this wealth to themselves. (Some of Marx's insights were seen in a rudimentary form by the "Ricardian socialist" school [1] [2].) He developed this theory of exploitation in Capital: A Critique of Political Economy, a "dialectical" investigation into the forms value relations take.

Marx's theory of business cycles; of economic growth and development, especially in two sector models; and of the declining rate of profit, or crisis theory, are other important elements of Marx's political economy. Marx later made tentative movements towards econometric investigations of his ideas, but the necessary statistical techniques of national accounting only emerged in the following century. In any case, it has proved difficult to adapt Marx's economic concepts, which refer to social relations, to measurable aggregated stocks and flows. In recent decades, however, a loose "quantitative" school of Marxist economists has emerged. While it may be impossible to find exact measures of Marx's variables from price data, approximations of basic trends are possible.

French socialism

Jean-Jacques Rousseau
Rousseau was one of the first modern writers to seriously attack the institution of private property, and therefore is sometimes considered a forebear of modern socialism and communism, though Marx rarely mentions Rousseau in his writings. He argued that the goal of government should be to secure freedom, equality, and justice for all within the state, regardless of the will of the majority. From Jean-Jacques Rousseau came the idea of egalitarian democracy.

Charles Fourier and Henri de Saint-Simon
In 1833 Frances was experiencing a number of social problems arising out of the Industrial Revolution. A number of sweeping plans of reform were developed by thinkers on the left. Among the more grandiose were the plans of Charles Fourier and the followers of Saint-Simon. Fourier wanted to replace modern cities with utopian communities, while the Saint-Simonians advocated directing the economy by manipulating credit. Although these programs didn’t have much support, they did expand the political and social imagination of their contemporaries, including Marx. [4]

Louis Blanc
Louis Blanc is perhaps best known for originating the social principle, later adopted by Marx, of how labor and income should be distributed: “From each according to his abilities, to each according to his needs.” [5]

Pierre-Joseph Proudhon
Pierre-Joseph Proudhon participated in the February 1848 uprising and the composition of what he termed "the first republican proclamation" of the new republic. But he had misgivings about the new government because it was pursuing political reform at the expense of the socio-economic reform, which Proudhon considered basic. Proudhon published his own perspective for reform, Solution du problème social, in which he laid out a program of mutual financial cooperation among workers. He believed this would transfer control of economic relations from capitalists and financiers to workers. It was Proudhon's book What is Property? that convinced the young Karl Marx that private property should be abolished.

In one of his first works, The Holy Family, Marx said, "Not only does Proudhon write in the interest of the proletarians, he is himself a proletarian, an ouvrier. His work is a scientific manifesto of the French proletariat." Marx, however, disagreed with Proudhon's anarchism and later published vicious criticisms of Proudhon. Marx wrote The Poverty of Philosophy as a refutation of Proudhon's The Philosophy of Poverty. In his socialism, Proudhon was followed by Mikhail Bakunin. After Bakunin's death, his libertarian socialism diverged into anarchist communism and collectivist anarchism, with notable proponents such as Peter Kropotkin and Joseph Déjacque.

Other influences

Engels
Marx's revision of Hegelianism was also influenced by Engels' book, ‘’The Condition of the Working Class’’ in England in 1844, which led Marx to conceive of the historical dialectic in terms of class conflict and to see the modern working class as the most progressive force for revolution. Thereafter Engels and Marx worked together for the rest of Marx's life, so that the collected works of Marx and Engels are generally published together, almost as if the output of one person. Important publications, such as the German Ideology and the Communist Manifesto, were joint efforts. Engels says "I cannot deny that both before and during my 40 years’ collaboration with Marx I had a certain independent share in laying the foundation of the theory, and more particularly in its elaboration." But he adds

“ But the greater part of its leading basic principles, especially in the realm of economics and history, and, above all, their final trenchant formulation, belong to Marx. What I contributed — at any rate with the exception of my work in a few special fields — Marx could very well have done without me. What Marx accomplished I would not have achieved. Marx stood higher, saw further, and took a wider and quicker view than all the rest of us. Marx was a genius; we others were at best talented. Without him the theory would not be by far what it is today. It therefore rightly bears his name.(Frederick Engels, Ludwig Feuerbach and the End of Classical German Philosophy Part 4: Marx) ”

Antique materialism
Marx was influenced by Antique materialism, especially Epicurus (to whom Marx dedicated his thesis, ‘’Difference of natural philosophy between Democritus and Epicurus’’, 1841) for his materialism and theory of clinamen which opened up a realm of liberty.

Lewis Morgan
Marx drew on Lewis H. Morgan and his social evolution theory. He wrote a collection of notebooks from his reading of Lewis Morgan but they are regarded as being quite obscure and only available in scholarly editions.

Giambattista Vico
Giambattista Vico propounded a cyclical theory of history, according to which human societies progress through a series of stages from barbarism to civilization and then return to barbarism. In the first stage (called the Age of the Gods) religion, the family, and other basic institutions emerge; in the succeeding Age of Heroes, the common people are kept in subjection by a dominant class of nobles; in the final stage (the Age of Men) the people rebel and win equality, but in the process society begins to disintegrate. The connection between Vico's theory of history, and Marx's account of the evolution of society is apparent. [6]

Charles Darwin
Marx read Darwin's The Origin of Species and recognized its value in supporting his theory of class struggle. He even sent Darwin a personally inscribed copy of Das Kapital in 1873.[7] Marx understood that Darwin's work both helped to explain the internal struggles of human society, and provided a material explanation for the processes of nature. [8]

In 1861, Karl Marx wrote to his friend Ferdinand Lassalle, "Darwin’s work is most important and suits my purpose in that it provides a basis in natural science for the historical class struggle. ... Despite all shortcomings, it is here that, for the first time, ‘teleology’ in natural science is not only dealt a mortal blow but its rational meaning is empirically explained."

Having read Darwin's work and mentioned Darwin by name in Das Kapital, it is presumable that Marx may have been influenced to some degree by Darwin, however, the depth of that influence, if any, would certainly seem to be greatly exaggerated by a number of religious fundamentalists that seek to paint Darwin's ideas as incredibly dangerous.

For instance, in The Disasters Darwinism Brought to Humanity, Harun Yahra writes: "Karl Marx, the founder of Communism, adapted Darwin's ideas, which deeply influenced him, to the dialectic process of history."

Yahra also writes: "Marx revealed his sympathy for Darwin by dedicating his most important work, Das Kapital, to him." [9]

This last bit is a common misconception that arose from a letter from Darwin to Edward Aveling, (who later became the lover of Marx's daughter, Eleanor). Aveling had written to Darwin about wanting to dedicate his book to him, but Darwin declined and Darwin's response became mixed with Karl Marx's papers when Eleanor Marx inherited her father's papers from Engels. The letter was published in 1931 in the Russian Communist magazine, Under the Banner of Marxism, which went on to suggest that the enclosures referred to in the letter might have been chapters from Das Kapital that dealt with evolution. It was not until 1975 that Aveling's letter to Darwin was discovered, debunking this myth. [10]