During the last quarter of the twentieth century, Soviet Russian philosophy did away with ideology in the fields of Science; but until the mid-1980s, scientists could not escape intense ideological scrutiny. A great number of Soviet scientists did their best to avoid this ideological supervision, and pursued their research, remaining neutral toward Marxist ideology. Among these fields of research were so called "philosophical problems of natural sciences" (The Western counterpart would have been the Philosophy of Science). Some Soviet Russian philosophers put forward original conceptions of scientific development, the structural features of science, and/or provided novel interpretations of certain scientific principles and ideas. These thinkers had deep roots in Marxism, though not orthodox Marxism. They, so to speak, overcame classical Marxism and proposed innovative ideas largely based upon epistemological considerations. The legacies of I. S. Alekseev and M. A. Rozov are especially worthy of attention for their original epistemological contributions to the philosophy of science.