Ranciere makes an excellent point about the conflation of abstraction and alienation qua essence in thought in what follows, which might also serve as grounds for a critique of Hegelian-Marxism:
‘The concept of abstraction in the anthropological critique is the basis of a fundamental misunderstanding. It refers both to a process which takes place in reality; and at the same time to the logical steps which belong to a certain type of discourse.
Abstract is in fact taken here in the sense of separated. The abstraction (separation) takes places when the human essence is separated from man, and his predicates are fixed in an alien being. The speculation starts off from this abstraction, from this separation from the original unity. In that state the predicate exists separated from the subject. But this separation from the original unity is at the same time the setting up of a new unity – to the advantage of the estranged being in which the essence of the subject is alienated. That is what enables the predicate to pose as the true subject. That is how theologians, who start off from the division between man and his essence alienated in God, make God the real subject. In the same way speculative philosophy, i.e. Hegelian philosophy, starts off from thought separated from its subject, man, in order to make the abstract ideas the real subject of the experience.
Thus we read in Feuerbach’s Philosophy of the Future no. 23
‘The essence of God is none other in Hegel than the essence of thought; or thought separated by abstraction from the thinking ego. The philosophy of Hegel, has made from thought, from the subjective being, but which is thought without the subject, and thus represented as a being distinct from himself, the being divine and absolute’.
What is important here is that abstraction as an instrument of thought is disqualified. All thinking which seeks to proceed by scientific abstraction (in the sense explained by Marx in the general Introduction of 1857) is accused of maintaining the separation of the abstract moments from human experience.
Thus, in the Provisional Theses for the Reform of Philosophy, Feuerbach characterises abstraction as alienation:
“To abstract is to pose the essence of nature outside of nature, the essence of thought outside the act of thinking. By founding his whole system on these acts of abstraction, Hegel’s philosophy alienated man from himself. It identifies clearly what it separates, but in a way which itself involves in its turn, separation and mediation”. (thesis. No.20)
To anticipate, we may say that which is confused here in this theory of abstraction are the two processes which Marx distinguishes as the process of thought and the real process in the general Introduction of 1857.’