This paper analyzes the notion of sexual perversion from a philosophical stance. Sexual perversion is difficult to analyze because the notion of sex is itself ambiguous and unclear. Alan Soble identifies five central distinctions within the conceptual philosophy of sex that define the concept of the sexual act as 1) involving contact with a sex organ, 2) serving a procreative function, 3) producing sexual pleasure, 4) relying on intention or purpose, 5) being defined in terms of sexual desire. However, none of these definitions is sufficient. The philosopher Thomas Nagel set out a psychological standard that remains useful today. He defined the purpose of sexual desire as one of communication among the participants. According to Nagel, sex has an overlapping system of sexual perceptions and interactions: it involves a desire that one's partner be aroused by the recognition of one's desire that he or she be aroused. Nagel's theory, known as the "communication model", proposes a purpose for the sexual act and attempts to explain the essence of perversion. It proposes that the act of blocking off the communication results in the perversion. This model has a number of problems, however. For example, it implies that sexual relations between regular partners are inferior to novel encounters because less remains to be communicated sexually. Why is such a conclusion derived? Because the communication model is built up with equivocal and ambiguous structure, it involves both external and internal moral criteria. The coexistence of both types of criteria is the source of the model's problems.
