Why Marx left philosophy for social science

It is customary to distinguish between philosophically oriented 'critical psychologists, and 'mainstream psychologists' who are committed to a scientific approach to the study of human behavior. In this article, we highlight a fundamental irony concerning the critical psychology movement, especially with respect to those contributions that appeal to Karl Marx and his legacy to justify the criticism or rejection of traditional Scientific methods in approaching the subject matter of psychology on moral and/or epistemological grounds. The irony is that Marx's own intellectual development led him to abandon philosophy in favor of empirically grounded forms of investigation resembling those of today's 'mainstream' social sciences. Unlike many contemporary critics who see little or nothing of possible value in the image and methods of sociology and psychology as Sciences, Marx's own work sought to integrate critical, value-laden aims with a serious commitment to establishing independently verifiable facts. After examining a range of historical and biographical explanations given for Marx's change of heart, we show that Marx was one of the world's first social scientists. We highlight the characteristic features of a critical, empirically oriented Marxian social science, paying special attention to issues of continuing theoretical and meta-theoretical relevance in sociology, psychology and their intersection.