According to Lacan, psychosis cannot be the result of repression. He argues that Freud's classic studies on the unconscious, that is, The Interpretation of Dreams, The Psychopathology of Everyday Life, Jokes and their Relation to the Unconscious, indicate that the mechanism of repression and the return of the repressed are linguistic in nature. That the unconscious is structured like a language implies that for something to be repressed it has to have been previously acknowledged by the subject, implying prior recognition within the symbolic register.
When the child's symbolic universe is created it is possible for a signifier to be excluded from the symbolic altogether and thus never to form part of it. It is this exclusion or foreclosure of a fundamental linguistic element, a key signifier, at the moment of the genesis of the symbolic that results in a psychotic subject. Foreclosure contrasts with repression, in that what is foreclosed is excluded from the symbolic system altogether; it has never been registered there and therefore, so far as the symbolic is concerned, simply does not exist. Yet what is foreclosed from the symbolic is not purely and simply abolished. It returns, but, unlike the return of the repressed, it returns from outside the subject, as emanating from his environment in one form or another – a phenomenon not to be confused with projection, which is not specific to psychosis.
Psychosis involves a form of regression – topographical rather than chronological – from the symbolic register to the imaginary. That is, what has been foreclosed from the symbolic reappears in the real, which is not the same as reality, and it is marked by the properties of the imaginary. In particular, relations with the other are marked by erotic attachment and aggressive rivalry. Thus, Professor Flechsig becomes an erotic object for Schreber but also the agent of Schreber's persecution. The homosexuality in Schreber that Freud highlighted is therefore treated not as a cause of Schreber's psychosis but rather as a symptom produced by the psychotic foreclosure.
Foreclosure may well be a normal psychic process; it is only when what is foreclosed is specifically concerned with the question of the father, as in Schreber's case, that psychosis is produced. Using a term to indicate that what is at issue is a signifier and not a person, and that this signifier is replete with cultural and religious significance, Lacan refers to this signifier that is missing in psychosis as the Name-of-the-Father. The Name-of-the- Father is a key signifier for the subject's symbolic universe, regulating this order and giving it its structure. Its function in the Oedipus complex is to be the vehicle of the law that regulates desire – both the subject's desire and the omnipotent desire of the maternal figure.
Since foreclosure of the Name-of-the-Father is an outcome of the Oedipus complex, it follows that the psychotic structure is laid down for a subject at the time of negotiating the Oedipus complex. This implies that the psychotic structure will have existed all along, like a hairline fracture, for many years prior to the clinical appearance of the psychosis when it suddenly and dramatically appears. And we can see this in Schreber, who, after all, had up until the age of fifty-one led a relatively normal life, enjoying a successful career, and carrying out quite demanding duties on the bench.
Lacan holds that it is a certain type of encounter, in which the Name-of-the-Father is 'called into symbolic opposition to the subject', that triggers psychosis (Écrits, 1977, p. 217). In the seminar on psychosis there is a discussion of the function of l'appel, the call, the calling, the appeal or the interpellation. The discussion is not related specifically to psychosis but rather to a quite general linguistic function. The basic idea is captured in the English distinction between, for example, the two statements: 'You are the one who will follow me', and 'You are the one who shall follow me.'
It is possible to take the first as a description of or prediction about something that will come to pass: 'I predict that you will follow me.' The second, on the other hand, can serve as an appeal, where the interlocutor is called upon to make a decision, to pursue a course of action that he must either embrace or repudiate. This latter case is for instance exemplified by Jesus of Nazareth's invocation to his disciples-to-be, where 'You are the ones who shall follow me' means something like this: 'I say to you, "You are the ones who shall follow me." Now, tell me, what is your reply, what do you say to this? Give me your answer, for now is the time to choose.' In this example Jesus is 'in symbolic opposition to' his disciples, he is asking them, for 'symbolic recognition', since his speech calls upon them to respond in a way that commits them to a decision, one loaded with practical consequences, as to whether they are to recognize him as the Messiah.
For Schreber there is a momen when he is called, interpellated, by, or better, in the Name-of-the-Father, and the lack of the signfier declares itself. This is sufficient to trigger the psychosis.
In psychosis this symbolic opposition, this call for symbolic recognition, is brought about by an encounter with 'a real father, not necessarily by the subject's own father, but by A-father' – a situation that arises under two conditions: when the subject is in a particularly intense relation with a strong narcissistic component; and when, in this situation, the question of the father arises from a third position, one that is external to the erotic relation.
It may occur, 'for the woman who has just given birth, in her husband's face; for the penitent confessing his sins in the person of his confessor, for the girl in love in meeting "the young man's father"' (Écrits, 1977, p. 217). It can also occur in analysis, where the development of the transference can precipitate a psychosis.
Once the psychosis is triggered, everything will have changed for good, but what about before the onset? It is in pursuing this question that Lacan discusses Hélène Deutsch's work, in which she refers to the 'as if' phenomenon, where, for example, an adolescent boy identifies with another youth in what looks like a homosexual attachment but turns out to be a precursor of psychosis. Here there is something that plays the role of a suppléance, a substitute, a stand-in, for what is missing at the level of the symbolic. Lacan use an analogy to explain this notion of a substitute or stand-in for what is lacking in the symbolic:
Not every stool has four legs. There are some that stand upright on three. Here, though, there is no question of their lacking any, otherwise things go very badly indeed ... It is possible that at the outset the stool doesn't have enough legs, but that up to a certain point it will nevertheless stand up, when the subject, at a certain crossroads of his biographical history, is confronted by this lack that has always existed (Seminar III, The Psychoses, p. 265).
It is intriguing that some psychotics have been capable of making important scientific or artistic contributions. Cantor, the mathematician, is a famous example we know about because of the documented psychotic episodes he underwent. But Lacan also speculates that there may be cases where the psychosis never declares itself and the clinical phenomena never eventuate. Perhaps in these cases the (pre-)psychotic subject may find a form of substitute for the foreclosed signifier that enables the subject to maintain the minimum symbolic links necessary for normal, even for highly original and creative, functioning.
Lacan argues in Le Sinthome (1976) that there are a number of indications suggesting that James Joyce was probably such a case: a psychotic who was able to use his writing as an effective substitute that prevented the onset of psychosis. Though necessarily speculativ , such a line of thought raises important issues here to do with the diagnosis of psychosis – could, for example, the so-called borderlines be situated here?
Lacan admonished psychoanalysts not to back away from the treatment of psychosis. Lacan received psychotics, and today most Lacanian analysts are prepared to work with psychotics. Indeed, there are psychoanalyst-psychiatrists in France and elsewhere who have instituted the regular and systematic treatment of psychotics in State psychiatric services – services, note, that receive no special funding vis-à-vis those employing more typical psychiatric approaches. Two major issues are raised by the treatment of psychotics: the handling of the transference and, the aim of the treatment, and these have been extensively addressed by Lacanian analysts.
The main points of Lacan's theory of psychosis can be summarized as follows: • A specific mechanism, foreclosure of the Name-of-the-Father, produces psychosis. This key signifier is not admitted to the symbolic system, leaving a hole where this signifier would normally be.
• Onset of psychosis is triggered, years later, by a particular type of encounter, which Lacan calls an encounter with A-father.
See also: aggressivity, Borromean knot, desire, discourse, foreclosure, imaginary, Name-of-the-Father, real, symbolic, treatment Other terms: neurosis, Oedipal complex, perversion, repression, structure, suppléance, symptom, transference, unconscious
Freud, S. (1951)  'Psycho-Analytic Notes on an Autobiographical Account of a Case of Paranoia (Dementia Paranoides)', (vol. 12, p. 3) Standard Edition, The Complete Psychological Works of Sigmund Freud. London: Hogarth Press. Freud, S. (1986) [1900-01] The Interpretation of Dreams (SE vols 4, 5). Freud, S. (1986)  The Psychopathology of Everyday Life (SE vol. 6). Freud, S. (1986)  Jokes and their Relation to the Unconscious (SEvol. 7). Lacan, J. (1993) [1955-56] Seminar III: The Psychosis (trans. R. Grigg). New York: W.W. Norton. Lacan, J. (1977)  'On a question preliminary to any possible treatment of psychosis', Écrits: A Selection (trans. A. Sheridan). London: Tavistock. Lacan, J. (1976) Le Sinthome, Séminaire XXIII (1975-76), Ornicar? 6, 7, 8, 9, 10, 11 [Provisional transcription].