For Žižek, only Christ makes atheism possible, functioning as a ‘transitional object’ like the favourite teddy bear of a small child negotiating the relationship between internal and external worlds. The teddy bear both is and is not the child, is and is not the external world, and by marking the distinction between the two acts both as a bridge and a border, creating the two spheres between which it mediates. Eventually the bear loses its function as the antagonism between inner and outer worlds is inscribed throughout reality as the child knows it, and is in fact constitutive of this reality. Both inner and outer reality are functions of the human mind, and human subjectivity is possible only insofar as some element of the subject evades the subject’s control. We made the world, but it overwhelms us, and the element of the world which is beyond our control is the ‘monstrosity’ which is Christ. Christ, like the teddy bear, is a ‘vanishing mediator’, expressing our alienation from ourselves, and, by dying, forcing us to the realisation that this alienation is within us, is constitutive of our very selves.- Marika Rose, "A modest plea for a Chestertonian reading of the Monstrosity of Christ"
As we rely on alienation for selfhood, so law relies on transgression. Law appears as an imposition from outside, forbidding the satisfaction of our innermost desires, when in fact it is prohibition which creates those desires. The key to escaping the destructive cycle of law, sin and desire is not to move beyond the law to love, but to recognise that both law and sin are within us - that there is no ‘big Other’, no transcendent parental lawgiver - and to fully embrace the law as our own self. Only Christianity makes such an atheism possible, because only in Christianity does God die. This is why Žižek is a Protestant: our ethical choices are not mediated to us by our communities, but each of us is responsible for ourselves alone. ‘The true formula of atheism is “there is no big Other”.'
A vanishing mediator is a concept that exists to mediate between two opposing ideas, as a transition occurs between them. At the point where one idea has been replaced by the other, and the concept is no longer required, the mediator vanishes. In terms of Hegelian dialectics the conflict between the theoretical abstraction and its empirical negation (through trial and error) is resolved by a concretion of the two ideas, representing a theoretical abstraction taking into account the previous contradiction, whereupon the mediator vanishes.
In terms of psychoanalytic theory, when someone is caught in a dilemma they experience Hysteria. A conceptual deadlock exists until the resulting Hysteric breakdown precipitates some kind of resolution, therefore the Hysteria is a vanishing mediator in this case.
from the "Critique of Pure Interest" blog:
Thus in the following syllogism:
“Every human is mortal
Socrates is a human
Therefore Socrates is mortal”
the term “human” is the middle term mediating between “Socrates” and “mortal” (each of which Aristotle calls an “extreme”, akron). The middle term allowes the extremes to be linked in the conclusion. Note that the middle term itself does not appear in the conclusion. It is in fact common knowledge in Aristotelian syllogistics that middle terms never appear in the conclusions they make possible by mediating between the premises: middle terms disappear once they have fulfilled their mediating function. Hence the fact that the middle term is traditionally also known as the “silent term”.