The subject ($) is trapped by the Other through a paradoxical object-cause of desire in the midst if it (a), through this secret supposed to be hidden in the Other: $<>a -- the Lacanian formula of fantasy. (...) The fundamental Lacanian thesis of fantasy is that in the opposition between dream and reality, fantasy is on the side of reality: it is, as Lacan once said, the support that gives consistency to what we call 'reality'.Zizek, Slavoj. "The Sublime Object of Ideology" (1989)
When Lacan says that the last support of what we call 'reality' is a fantasy, this is definitely not to be understood in the sense of 'life is just a dream', 'what we call reality is just an illusion', and so forth. (...) The Lacanian thesis is, on the contrary, that there is always a kernel, a leftover which persists and cannot be reduced to a universal play of illusory mirroring. The difference between Lacan and 'naive realism' is that for Lacan, the only point at which we approach this hard kernel of the Real is indeed the dream. When we awaken into reality after a dream, we usually say to ourselves 'it was just a dream', thereby blinding ourselves to the fact that in our everyday, wakening reality we are nothing but a consciousness of this dream. It was only in the dream that we approached the fantasy-framework which determines our activity, our mode of acting in reality itself.
The fascinating 'secret' [of a narration] is precisely the Lacanian objet petit a, the chimerical object of fantasy, the object causing our desire and at the same time--this is the paradox--posed retroactively by this desire; in 'going through the fantasy' we experience how this fantasy-object (the 'secret') only materializes the void of our desire.
[Lacan] tried to isolate [the] dimension of enjoyment as that of fantasy, and to oppose symptom ond fantasy through a whole set of distinctive features: symptom is a signifying formation which, so to speak, 'overtakes itself' towards its interpretation--that is, which can be analysed; fantasy is an inert consruction which cannot be analysed, which resists interpretation. Symptom implies and addresses some non-barred, consistent big-Other which will retroactively confer on it its meaning; fantasy implies a crossed out, blocked, barred, non-whole, inconsistent Other--that is to say, it is filling out a void in the Other.
Lacan put, at the end of the curve designating the question 'Che vuoi?' the formula of fantasy ($<>a): fantasy is an answer to this 'Che vuoi?' ; it is an attempt to fill out the gap of the question with an answer.
Fantasy appears, then, as an answer to 'Che vuoi?' , to the unbearable enigma of the desire of the Other, of the lack in the Other; but is is at the same time fantasy itself which, so to speak, provides the co-ordinates of our desire--which constructs the frame enabling us to desire something. The usual definition of fantasy ('an imagined scenario representing the realization of desire') is therefore somewhat misleading, or at least ambiguous: in the fantasy-scene the desire is not fulfilled, 'satisfied', but constituted (given its objects, and so on)--through fantasy, we learn 'how to desire'. In this intermediate position lies the paradox lies the paradox of fantasy: it is the frame co-ordinating our desire, but at the same time a defence against 'Che vuoi?' , a screen concealing the gap, the abyss of desire of the Other. Sharpening the paradox to its utmost--to tautology--we could say that desire itself is a defence against desire: the desire structured through fantasy is a defence against the desire of the Other, against this 'pure', trans-phantasmic desire (i.e. the 'death drive' in its pure form).
The way fantasy functions can be explained through reference to Kant's Critique of Pure Reason: The role of fantasy in the economy of desire is homologous to that of transcendental schematism in the process of knowledge (Baas, 1987). In Kant, transcendental schematism is a mediator, an intermediary agency between empirical content (contingent, inner-worldly, empirical objects of experience) and the network of transcendental categories: it is the name of the mechanism through which empirical objects are included in the network of transcendental categories which determine the way we perceive and conceive them (as substances with properties, sunmitted to casual links, and so on). A homologous mechanism is at work with fantasy: how does an empirical, positively given object become an object of desire; how does it begin to contain some X, some unknown quality, something which is 'in it more than it' and makes it worthy of our desire? by entering the framework of fantasy, by being included in a fantasy-scene which gives consistency to the subject's desire.
Fantasy conceals the fact that the Other, the symbolic order, is structured around some traumatic impossibility, around something which cannot be symbolized--i.e. the real of jouissance: through fantasy, jouissance is domesticated, 'gentrified'--so what happens with desire afetr we 'traverse' fantasy? Lacan's answer, in the last pages of his Seminar XI, is drive, ultimately the death drive: 'beyond fantasy there is no yearning or some kindred sublime phenomenon, 'beyond fantasy' we find only drive, its pulsation around the sinthome. 'Going-through-the-fantasy' is therefore strictly correlative to identification with sinthome.
Fantasy is a basic scenario filling out the empty space of a fundamental impossibility, a screen masking a void. 'There is no sexual relationship', and this impossibility is filled out by the fascinating fantasy-scenario--that is why fantasy is, in the last resort, always a fantasy of the sexual relationship, a staging of it. As such, fantasy is not to be interpreted, only 'traversed': all we have to do is experience how there is nothing 'behind' it, and how fantasy masks precisely this 'nothing'.
In the third period [of the psychoanalytic cure we have the big Other, the symbolic order, with a traumatic element at its very heart; and in Lacanian theory the fantasy is conceived as a construction allowing the subject to come to terms with this traumatic kernel. At this level, the final moment of the analysis is defined as 'going through the fantasy [la traversée du fantasme]': not its symbolic interpretation but the experience of the fact that the fantasy-object, by its fascinating presence, is merely filling out a lack, a void in the Other. There is nothing 'behind' the fantasy; the fantasy is a construction whose function is to hide this void, this 'nothing'--that is, the lack in the Other.
The Real is therefore simultaneously both the hard, impenetrable kernel resisting symbolization and a pure chimerical entity which has in itself no ontological consistency. (...) As we have already seen, this is precisely what defines the notion of traumatic event: a point of failure of symbolization, but at the same time never given in its positivity--it can be constructed only backwards, from its structural effects. All its effectivity lies in the distortions it produces in the symbolic structure and, as such, the retroactive effect of this structure.
What the object is masking, dissimulating, by its massive, fascinating presence, is not some other positivity but its own place, the void, the lack that it is filling in by its presence--the lack in the Other. And what Lacan calls 'going-through the fantasy' consists precisely in the experience of such an inversion apropos of the fantasy-object: the subject must undergo the experience of how the ever-lacking object-cause of desire is in itself nothing but an objectification, and embodiment of a certain lack; of how its fascinating presence is here only to mask the emptiness of the place it occupies, the emptiness which is exactly the lack in the Other--which makes the big Other (the symbolic order) perforated, inconsistent.