June 4, 2018:
Finally, "Theory" — capital-T — is the theory of practice in general, while "philosophy" in this first period is the theory of theoretical practice, or, if you like, the science of the sciences, a regional subset of Theory. These related but I think sometimes elided concepts define a privileged ground from which the scientificity of theories can be determined. At this time in Althusser's evolution there's a triumphalism orbiting these concepts: a palpable sense of, "This is it! We found it!", which Althusser would soon reject. In self-critically taking stock of the results of this first phase, Althusser criticized this formula as "positivist" and "theoreticist", producing in the next period a very different concept of "philosophy".