This paper tries to reconstruct the way Bruno Latour thinks of science, by concentrating mainly on his book Pandora's Hope, which is applicable for this intention, because of the multiplicity of its topics. Latour wants to overcome the dichotomy of constructivism and naturalism. This ambition will be demonstrated on some of his key concepts. The idea of circulating reference is meant to be the replacement of the subject-object dichotomy. He also has a peculiar answer to the question whether the objects of science are fabricated or real. Latour's approach also makes it possible to judge scientific research programmes. The traditional dichotomy of extemalism and intemalism in the sociology of science is replaced by Latour by the concept of the circulatory system of science. Latour's theory owes much to his anthropological perspective on science.