MARX'S use of the term science clearly encompassed the social as well as the natural sciences, obvious from his use of terms such as the “science of political economy.” Marx nowhere spells out explicitly the differences between the meanings of the term science in the two domains, but his constant criticism of the classical political economists before him and his contemporaries, provide many pointers to what these are. Foremost among these is the class standpoint that is inherent in any study of society and therefore the content of the social sciences. In the case of the natural sciences the greatest effort has to be expended in the initial stages of its historical development to distinguish reality from illusion. As Marx elegantly phrases it, the aim of science is to discover the essence underlying the appearance, and so it is too in the social sciences. And in the realm of political economy that was precisely the goal of his studies in Capital. But more importantly Marx also recognised that what was illusion in the case of the natural sciences, was not only illusion but also ideology when it came to the social sciences. Holding on to the wrong conceptual framework or understanding of the social world was ideology, or false consciousness, the opposite of science. And the roots of why science was set aside, by individuals, groups or classes, in favour of ideology lay in their class bias. The science of society therefore had also to have a theory of ideology, of how and why ideology differed from the sciences, and what gave rise to the different ideologies from the viewpoint of different classes in society. 

This was not to argue that no such problem affected the natural sciences at all. Marx and Engels especially recognised this in the reception accorded to Darwin's theory of evolution in their day. In their characteristically gleeful exchanges in their correspondence, they remarked on how scientists read their own class bias into their interpretation of Darwin's work, how scientists who had till the other day spoken of the harmony in nature, suddenly turned to talking about competition and struggle as fundamental to nature's working. Yet this did not mean sinking into the mess of relativism, of declaring that there was no science at all, or declaring that in bourgeois society all science was simply bourgeois ideology. Darwin's theory of evolution was science, even if Darwin himself or his fellow scientists were confused about its interpretation, confusions that could only be settled with further development of the science.

The problem however was posed differently in the social sciences. While ideology originated from the viewpoint of a hegemonic class in society, which could not comprehend its own eventual end, science belonged to the class that could see how to transform the existing social and economic order to transcend the current mode of production. As ideology, bourgeois economic theory tended constantly, for Marx, to descend to the “vulgar”, meaning the abandoning of the quest for the essence beyond the appearance. On the other hand, it could only be an exploited class whose deepest self-interest lay in the transformation of the current economic, social and political order that could adopt a truly scientific attitude which would encompass the necessity of such a transformation. Throughout the history of Marxist thought, especially in the 20th century, the question of the class origins of and the hegemony of the ruling class viewpoint in social thought has been uncritically and incorrectly applied to the natural sciences without regard to the specific differences between the two, differences that Marx and Engels were keenly aware of. 

But the real key to Marx's perspective on science, encompassing both the natural and social world, is the philosophical standpoint of materialist dialectics that was Marx's mature world-view. He drew much from Hegel's dialectics, including his early acquaintance with it, moving on later to an unsparing critique, inspired a great deal by Feuerbach, but returning to rework it in materialist fashion, especially in the Grundrisse and then in Capital.  Marx firmly avoided both Feuerbach's mechanical outlook as well as Hegel's constant slide into idealism. But Marx's materialist dialectics was no mere juxtaposition or formal combination of elements of one and the other. It was an internally unified worldview where dialectics and materialism were necessary aspects of each other. This materialist dialectics encompassed the study of nature as well as society and its logic can clearly be seen at work in Capital, though Marx regrettably never put down in writing his  promise to “discover the rational kernel within the mystical shell” of Hegel’s dialectics.

It is in this context that the significance of Engels' comparison of Marx's achievements to that of Darwin, that we quoted at the beginning of this article, emerges most clearly. The key dialectical category in both theories is development, a term that captures the sense of growth and accumulation as well as increasing diversification that is characteristic of both political economy and biological evolution. Going deeper, in both cases this development arises from a process of reproduction, in the one through the cycle of production and circulation and in the other through simple biological reproduction. But this reproduction, and this is the key insight of dialectics, is also the expression or manifestation of the unity of essence and appearance.  So, in the case of capitalism it is the cycle of production and circulation as simple and extended reproduction from which arises the accumulation of capital. Similarly, the evolution of the diversity and multiplicity of the biological world arises from the action of the environment on the process of biological reproduction. In both cases the dialectical unity of necessity and chance is realised through this cycle of reproduction. Closer study of the similarities and differences between Marx's view of capitalist growth and accumulation and the Darwinian explanation of evolution should deepen our understanding of why Marx wrote to Engels after reading the Origin of Species, “this is the book that contains the basis in natural history for our view.”

Marx and Engels' viewpoint of materialist dialectics is perhaps even more significant in understanding Engels' observation that Marx “discovered the special law of motion governing the present-day capitalist mode of production.” What does the law of motion mean here? Many commentators have implied that there is an implicit determinism or teleology in Marx's view of the necessity of overcoming the capitalist mode of production. The unwary may suspect that Engels' language here is another manifestation of this. But such a misreading can only arise from ignoring the dialectical meaning of “the law of motion”.  For Marx and Engels it refers really to the contradiction between capital and labour and the unity of these two opposites in the capitalist mode of production. In materialist dialectics, motion is contradiction, whether it is mechanical motion (being there and not there at the same time) or motion in a more general sense. But contradiction remains abstract unless its nature is made explicit by the specific character of the unity of the opposites in the contradiction. When, as in the case of capital and labour, the opposites have their own capacity to act too, there can be no determinism or teleology.

In this bicentennial year, grasping Marx's view of science in its profound dialectical sense remains an indispensable aspect of the struggle for socialism and communism.