 Althusser’s initial revisions to his understanding of the social structure and knowledge production were informed by a renewed attention to the works of Lenin and by a seminar he convened at the ENS in 1967 for leading scientists and interested students. This course resulted in a series of papers, gathered together as Philosophy and the Spontaneous Philosophy of the Scientists (1967a), in which Althusser began rethinking the relations among philosophy, science, ideology, and politics. Though this revision was later to be made more explicit, one of the most striking aspects of these papers was Althusser’s abandonment of the Spinozistic claim that the different levels of theoretical practice were autonomous. He now maintained that there was no criterion sufficient to demarcate scientific from ideological concepts and that all theoretical concepts are marked by ideology. This did not mean, however, that any concept was as good as any other. Scientists, through their work on the material real, tended to generate better understandings of things than were available intuitively. Further, he argued that philosophy still had a role to play in the clarification of scientific concepts. This is the case because, no matter how much work scientists do to understand the material real and to generate better concepts, they must always employ ideological concepts to frame their investigations and its results. Marxist philosophers, he maintained, could be useful to scientists by pointing out, from the standpoint of politics and by the method of historical critique, where and how some of the concepts scientists employed were ideological. The result of this intervention of philosophy into politics would not be “truer” concepts, but ideas that were more “correct” or “right” in both the normative and positive senses of these words.