68 SOCIAL SCIENTIST countries which were not only the centres of the world's large-scale manufacturing industries, but were simultaneously the centres of world trade. Moreover, these countries established their hegemony all over the world. They colonized Asia, Africa, America and Oceania. In this period of ascendancy of the European industrial powers the prevalent philosophy among natural scientists in the West was mechanical materialism. But the situation changed in the second half of the nineteenth century. In the middle of the nineteenth century there were great political upheavals throughout Europe. The working class rose against the establM-ied authority in practically every country in Europe. For the first time, a new class, the proletariat, contended for power with the ruling capitalist class. As a result we witness a shift in the ideological stance of the ruling classes. In place of down-to-earth realism, we find various shades of idealism. Neo-Kantianism popularized the idea that the natural sciences are to be treated separately and differently from the social sciences. While the natural sciences were still being used to understand and transform nature, the social sciences were supposed to be incapable of changing socie^, they could only be descriptive of various facets of society. The Rive of Positivism But by the last decades of the nineteenth century, even Neo-Kantianism was replaced by Positivism. Positivism first arose as an attempt to rid knowledge of all philosophical and ideological content. But soon it became a philosophy in itself and has been variously labelled as Machism, positivism, logical positivism, physicalism, and so on. It still remains the main philosophy of the social as well as natural sciences, in the capitalist West. In the social sciences it has given rise to Pragmatism, Purposivism, and Behaviourism. In the natural science its various offshoots have been Machism, Positivism, and Physicalisms But the dominant idea in all these schools is the negation of philosophy, although in its negation, it itself has become a philosophy. I look at the philosophy of science not from the point of view of a philosopher but from the point of view of a physicist. The development of physics in the present century highlighted by the theory of relativity and quantum physics has been pictured as if supporting idealist philosophies in general and positivism in particular. I would like to refute this 'contention. But before I do that I would like briefly to recount the development of physics over the last one hundred years, since it was during this period that all the discoveries which have radically affected philosophy were made. Physics in the Last Hundred Years Till the sixties of the nineteenth century, physics was dominated by Newtonian mechanics, and the prevalent philosophy of science was