Socialism" in turn is a process that makes possible "the full development of the individual" and the ultimate realization of the "end" of history - "the true realm of freedom" - where the meaning of "freedom" derives from an appropriation of Hegel's idea of it as "the idea of humanity" and the human "destiny", the idea endorsed by Engels in his 1877 Anti-Duhring elabaoration of the relation between "freedom" and "necessity". (Engels having failed to see and Marx having neglected to point out to him that, at least according to Althusser's "reading", Marx had by then rejected these ideas.)
^^^^^^ CB: However, Althusser is probably mistaken on this point.
Not only did Marx read all of _Anti-Duhring_, but in _Capital_ he develops a concept of humanism ,in Athusser's sense of that term, based in the concept of human labor, which Althusser fails to notice in the "mature" Marx. In Theories of Surplus Labor (mature Marx) Marx uses this concept of Necessity himself in one passage.