Although it is morally permissible to use each other for all sorts of purposes as long as they involve our “work and services”, sexual interactions are different

Sexual desire objectifies by its nature because when X sexually desires Y, X desires Y’s body and body parts, especially the sexual ones, making it hard, if not impossible, to treat the humanity in Y as an end (Kant 1930 [1963: 164]). Only sexual desire among our inclinations is directed at human beings as such, not “their work and services” (Kant 1930 [1963: 163]). In almost every interaction with each other, we are interested in some ability, talent, or service that another can perform, an aspect intimately connected to their rationality. In these cases, either X does not desire Y’s body (but Y’s abilities, talents, or services) or X desires it but in service to Y’s abilities. Only with sexual desire (and, Kant says, in the rare case of cannibalism; 1930 [1963: 162–63]) does X desire Y as a body, as an object. X wants to enjoy Y herself, not her beautiful voice, her massaging abilities, etc. And if X desires Y’s abilities, it is in service to Y’s physicality. Their bodies become the objects, not the instruments, of our attention. Kant thought that only marriage can make objectification tolerable, though his argument is implausible (Kant 1930 [1963: 163]; see Soble 2013b, 2017b; Denis 2001; Wertheimer 2003: 130–135).

Consent is thus not sufficient for permissible sex because consenting to sex is consenting to objectification, to something wrong (Soble 2017b: 303–304). Kant’s view indicates also why including regard in a definition of “sexual objectification” is plausible: even though X and Y treat each other well during sex, they still regard each other as mere sex objects.

The phenomenology of sexual desire seems to confirm Kant’s point: The “other’s body, his or her lips, thighs, buttocks, and toes, are desired as the arousing parts they are, distinct from the person” (Soble 2013b: 302)

During a good sexual act, even with one’s lover, at some point they focus on ass, cock, pussy, tits, etc. (Vannoy 1980: 14). Kant’s view that sexual desire and activity are different-perhaps even unique-from other ways we view and interact with other people seems correct, providing support for the conclusion that sexual desire objectifies.

Sexual desire seems also powerful: its pull is strong and its voice loud, insisting, and persistent, so much so that people do irrational and immoral things to satisfy it. This might be a gendered feature of sexual desire, truer more of men than of women, though throughout history, and in today’s popular culture especially, women have often been portrayed as sexually insatiable (see Anderson & Struckman-Johnson 1998; Soble 2008: ch. 10). Of course, sexual partners normally observe limits on how they treat each other: they do not violate each other, treat each other literally as objects, and so on, exactly because they understand that they may not treat people in such ways. Thus, sexual desire operates within moral red lines.

The Kantian problem of objectification cannot be easily solved. Arguing that there is no objectification because human beings have no special moral status from which they can be lowered (Soble 2002: 53–63) does not meet Kant on his own grounds (as Soble insists in 2017b). Claiming that parties to the sexual act normally consent to it (Mappes 1987), that objectification is okay as long as the relationship is respectful (Nussbaum 1995: esp. 227–231), or that sexual partners attend to each other’s sexual needs (Goldman 1977: 282–283; Singer 1984: 382) also do not solve the problem because none addresses the nature of sexual desire (Soble 2017b).