Here I make good use of Sartre's recipe: the For-itself 'is what it is not and is not what it is' to define that impossibility of being itself which arises on the objective plane. In order to overcome its self-alienation, the self is now required to withdraw from its engagement with others, a development I examine as a function of the transition to the reflective plane, but which Heidegger examined under the head of 'authenticity'.
This is why I would situate Sartre's philosophy on the objective plane. Where Sartre differs from his logical, analytical, positivist, realist and materialist colleagues (whose thinking I would also situate on the objective plane) is in his having made us aware of the agonizing indifference of the material universe to the very existence of subjects like ourselves--so constituted that we can not help seeking humanly satisfying meanings in a material universe devoid of meaning.
Consider this typical passage: "The theory called subalternation located the continuity of scientific character, the bearer of scientificite, on a subjective rather than an objective plane
. Yet while the musician who takes her first principles from arithmetic can also study arithmetic, if she pleases, and follow the deductive links that bind them to higher first principles, the student of sacred doctrine has no independent access to the first principles it takes from the scientia enjoyed by God.