Marx (1818-83) has often been presented by his followers as a scientist rather than a moralist. He did not deal directly with the ethical issues that occupied the philosophers so far discussed. His Materialist conception of history is, rather, an attempt to explain all ideas, whether political, religious, or ethical, as the product of the particular economic stage that society has reached. Thus a feudal society will regard loyalty and obedience to one's lord as the chief virtues. A capitalist economy, on the other hand, requires a mobile labour force and expanding markets, so that freedom, especially the freedom to sell one's labour, is its key ethical conception. Because Marx saw ethics as a mere by-product of the economic basis of society, he frequently took a dismissive stance toward it. Echoing the Sophist Thrasymachus, Marx said that the "ideas of the ruling class are in every epoch the ruling ideas." With his coauthor Friedrich Engels, he was even more scornful in the Manifest der Kommunistischen Partei (1848; The Communist Manifesto), in which morality, law, and religion are referred to as "so many bourgeois prejudices behind which lurk in ambush just as many bourgeois interests."
A sweeping rejection of ethics, however, is difficult to reconcile with the highly moralistic tone of Marx's condemnation of the miseries the capitalist system inflicts upon the working class and with his obvious commitment to hastening the arrival of the Communist society that will end such iniquities. After Marx died, Engels tried to explain this apparent inconsistency by saying that as long as society was divided into classes, morality would serve the interests of the ruling class. A classless society, on the other hand, would be based on a truly human morality that served the interests of all human beings. This does make Marx's position consistent by setting him up as a critic, not of ethics as such, but rather of the class-based moralities that would prevail until the Communist revolution.
By studying Marx's earlier writings--those produced when he was a Young Hegelian--one obtains a slightly different, though not incompatible, impression of the place of ethics in Marx's thought. There seems no doubt that the young Marx, like Hegel, saw human freedom as the ultimate goal. He also held, as did Hegel, that freedom could only be obtained in a society in which the dichotomy between private interest and the general interest had disappeared. Under the influence of socialist ideas, however, he formed the view that merely knowing what was wrong with the world would not achieve anything. Only the abolition of private property could lead to the transformation of human nature and so bring about the reconciliation of the individual and the community. Theory, Marx concluded, had gone as far as it could; even the theoretical problems of ethics, as illustrated in Kant's division between reason and feeling, would remain insoluble unless one moved from theory to practice. This is what Marx meant in the famous thesis that is engraved on his tombstone: "The philosophers have only interpreted the world, in various ways; the point is to change it." The goal of changing the world stemmed from Marx's attempt to overcome one of the central problems of ethics; the means now passed beyond philosophy.