Changes

According to Lacan, the phallus at the outset represents what else the mother desires is in addition to the baby. Thus, a pre-oedipal triangle of mother, phallus, and infant arises. At first the infant tries to <i>be</i> the phallus for the mother until the moment of a crucial transformation when the child, after identifying the phallus as a static image of completeness and sufficiency, sees it as representing the mother's desire, and thus her lack. From then on, the phallus takes the form of something missing (-') within any imaginary, and hence libidinal, frame of reference. Thus the phallus comes to signify desire, Lacan says.

The intermittence of its erection, its ability to fade (compare Ernest Jones's concept of aphanisis), and even the fact that half of all humans do not have it have made the erect penis eminently suited to symbolize the crucial issues of being (subject) and having (object) in both sexes. The penis constitutes the key element in the asymmetrical division that, according to Roman Jakobson, characterizes any symbolic system.

In his seminar on female sexuality (1998), Lacan further specified what he meant by the term "phallic jouissance." He used the phallic signifier (Φ) in writing his "formulas of sexuation," which posit that every human being has to be on one side or the other of the sexual divide. A woman always has something of the phallus (she is not entirely castrated), and the man is only supposed to "have" the phallus when he fantasizes his castration. In Lacan's symbolic notation, the phallus takes on the formal role of a supplement, which adds to the castration complex the fact that "there is no sexual relation," as Lacan said, referring to the impossibility of writing an equation of the relationship between the sexes.