This logical requirement of the theory of economic determinism is exemplified in much of the rigidly scientific discussions of Socialists. Marx maintained that the value of commodities is all determined and created by labour, and that interest is the surplus which the labourer produces above the cost of his keep; nevertheless Marx did not formally assert that the labourer has a moral right to the whole product, nor that interest is theft. He set forth his theories of value and surplus value as positive explanations of economic facts, not as an ethical evaluation of human actions. His object was to show the causes and nature of value, wages, and interest, not to estimate the moral claims of the agents of production, or the morality of the distributive process. In his formal discussion of the theory of value and of surplus value, Marx said nothing that implied a belief in genuine moral responsibility, or that contradicted the principles of philosophical materialism and economic determinism. It is, therefore, quite erroneous to infer that, since the Marxian theory attributes all value and products to the action of labour, Marxian Socialists must condemn the interest-taker as a robber. Neither Marx nor any other Socialist authority, however, has always held consistently to this purely positive method of economic exposition. When they declare that the labourer is "exploited," that surplus value is "filched" from him, that the capitalist is a "parasite," etc., they are expressing and conveying distinct moral judgments. In their more popular writings Socialist authors do not seriously attempt to observe the logical requirements of their necessitarian philosophy. They assume the same ethical postulates, and give expression to the same ethical intuitions as the man who believes in the human soul and free will.[115] And the great majority of their followers likewise regard the question of distribution as a moral question, as a question of justice. In their view the labourer not only creates all value, but has a just claim to the whole product. _The Labour Theory of Value_