This paper argues that disavowal, the mechanism underlying perversion, is by its very nature self-contradictory and cannot be fully accounted for by either of Freud's psychical topographies. It is suggested that successive theorists have failed to solve this problem adequately, but have tended to discuss perversion in terms more appropriate to either neurosis or psychosis. This paper proposes that perversion displays a radically unique style of defence; it is described how this differs from repression in particular. Finally it is shown how analysis of the rhetoric of perverse fantasy can clarify the nature of this unique defensive strategy.