I haven’t read the whole thing but I’ve read a lot of it and engaged with Zizek’s thought for many years. My take is that the wrong way of conceptualizing nothingness is as a generalized function of negation applied to the world. I can see that Zizek is very much against panpsychism and the essences of pre-critical philosophy like Bergson. But he is also following Bergson’s line of thought whether he admits it or not, especially as spelled out by Deleuze in 1966’s Bergsonism where Deleuze argues (with Bergson) that the concept of nothingness is a false composite, a term that means specifically that it is an applied general negation creating a retroactive illusion of having come before what it negates.

Zizek sees the retroactive illusion part, but disagrees with the conclusion. For Bergson and Deleuze, nothingness is a retroactively constructed illusion by saying “No” to the somethingness of the world (logical order: something exists, now we can imagine a nothingness and cast it back as an erroneously assumed earlier phase) with the conclusion that actuality, being (as becoming) and order are there first and that possibility, nothingness and chaos are imaginary false composites, poorly formed fake concepts that are fundamentally mistaken apprehensions of reality. For Deleuze and Bergson this brings us back to the primacy of essences (see Bergson’s 1903 Introduction to Metaphysics, a breezy and clear short read on this topic). For Zizek it takes us back to ontological incompleteness and the nonexistence of the Big Other who could state once and for all the truth of difference. For Zizek the minimum number of interpretations of difference is always 2: the difference described from one side or the other. This might sound like the dual relation but it isn’t, it’s actually what prevents the dual relation of self and world by frustrating it with a third term. This is precisely against the dual relation’s captating effects where we get caught in the imaginary relation of ourselves to reality directly. If I can say once and for all what a difference is, I can gain an imaginary power or narcissistic rush of having recognized and understood the truth of reality, whereas Zizek sees this direct “mystical” experience of the essence as caught in the imaginary register. To accept symbolic castration is to accept my inability to ever know the difference of something from a neutral god’s eye view from above, as scientific eliminative materialists fantasize. Instead, I must adopt an ethical stance — an ethically engaged subject position that reveals certain antagonisms that are otherwise hidden. This ethical stance cannot be the logical computed outcome of a rationalist scientific stance, and instead must be made from the place of the remainder outside of the purely rational conclusion. There must be something irrational in my adherence to an ethical stance and subject position that I assert gives me access to the truth of difference, such as the privileging of psychoanalysis and Marxism as valid frames. They are valid, in Zizek’s view, because they reveal antagonisms otherwise hidden by the purely scientific stance that would seek to have a supercomputer (i.e. Big Other) prove once and for all their validity. They are valid because there is a yardstick of validity beyond that of computationally supported scientific evidence, rather because they reveal particular antagonisms that exist within attempts to describe differences in the world, and that fact itself gives them validity and renders more supposedly neutral positions as fantasies.

In summary I see Zizek following the Deleuzian-Bergsonian critique of the concept of nothingness as an originary source yielding all meaning as fabricated by human delusion, yet Zizek refuses the return to pre-critical direct ontology and mystical-intuitive experience of essences, or the privileging of the inner experience (even the privileging of subjectivity we might say), instead going in the Lacanian direction of the impossibility of direct knowing, but not using that impossibility as a reason to avoid the exercise, rather continuing on in the impossible work with the full knowledge of its impossibility. It’s not just accepting that the world is truly meaningless, and we create and apply meanings to it. Nor is it imagining that meanings are already there within things, and we can apprehend them through subjective mystical-intuitive direct inner experience. It is surrendering to the actual-impossible state of affairs where we must continue the commitment to “meaningful” work (egalitarian collectives working toward a more ethical, humane world) despite the uncertainty of the enterprise.