Among the many topics in the philosophy of sex is permissible sexuality. Philosophy, however, sometimes tends to over-intellectualize discussion. What makes sex permissible may not be so strict. Drawing on Immanuel Kant's formulation of humanity, I argue that permissible sex requires only informed and voluntary consent, but under two conditions, which Thomas Mappes largely gets right. I then turn to Howard Klepper and argue that he is only half right and that permissible sexuality need not go beyond consent and its two conditions. In his formulation of humanity from the Metaphysics of Morals, Kant argues that we must treat humanity, in ourselves or in others, not only as a means but also as an end in itself. Therefore, according to Kant, sexuality is never permissible except in marriage. It says: Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay There is only one condition under which [sex] is possible: that while one person is acquired by the other as if it were one thing, that which is acquired in turn acquires the other; since in this way everyone finds themselves and restores their own personality. But acquiring a member of the human being is at the same time acquiring the whole person, since the person is an absolute unity. Therefore not only is it permissible for the sexes to surrender and accept each other on the condition of marriage, but it is possible to do so only on this condition ("Duties towards the body" 142). impossible to possess a person without violating the formulation of humanity unless that person also possesses you. So while you are possessed, you take yourself back as your possession by possessing the person who possesses you. And for Kant, once again, this is only possible in marriage. In any other sex, the two partners simply use each other as objects for sexual pleasure. Even if they both consent, their sex is not permitted by Kantian standards. The fact that only marriage can satisfy the formulation of humanity has troubling consequences for Kant's theory. First, this means that gay and lesbian sexuality is permissible even if it occurs in a monogamous, loving marriage. Kant lists homosexuality under the heading crimina carnis contra naturam as against the ends of humanity and as an abuse of sexuality (“Crimina Carnis” 144). It follows, however, that a homosexual relationship may be permissible simply if it satisfies the condition of marriage. Second: What about a loveless marriage? It is very likely that a married couple, who no longer love each other, perhaps on the verge of divorce, can have sexual relations similar to the occasional ones that strangers can have. Marriage is not enough to guarantee the formula of humanity. In the marriage described, in practice, nothing separates their sex from any other. Does the fact that they are married guarantee that they will treat each other to their ends? Kant is certainly not wrong, but perhaps he should not limit his considerations to marriage alone. Humanity's formulation contains further problems. The wording does not necessarily speak of human beings but of the humanity in the human being. We must view humanity, or the ability to reason and pursue our ends, as an end in itself. This means that when we use the services of a carpenter, for example, if he has freely motivated the carpentry business and has agreed to provide us with his services, we are allowed to use these services as a means when we act in a way to which he consents, for example, paying him for his work. To return to the topic, it follows thatwe can do the same with a prostitute if both parties agree. Kant's formulation therefore should not be limited to mere marriage. We are able to satisfy the wording and treat humanity as both a means and an end as long as we respect our partner's ends and obtain mutual consent. And this is exactly what they argue: informed and voluntary consent, described by Thomas Mappes in his account, is in fact sufficient to make sex permissible, that is, to use another sexually as a means and an end in itself. However, this is only true if we satisfy both Mappes conditions. We must (1) not lie and withhold information and (2) threaten and coerce when we have sex. The two conditions are necessary because we must remain ethical, but not to the extent described by Mappes. We violate condition one only with respect to sex itself. In other words, we only violate informed consent if we lie about wanting to have sex but not about intending to give our partner an orgasm. We also violate informed consent if we lie about sexual diseases or trick our partner into procreating. Thus, from Mappes' account, only scenarios (2) and (3) would appear to constitute a violation (Mappes, 234). Lying about orgasm - or rather not giving your partner orgasm - is a violation of informed consent because consenting to sex and not having orgasm is not sex at all. Lying about procreation is a violation because consenting to sex but instead procreating – assuming procreation was mutually agreed to be excluded – is once again not sex, but something else. And lying about sexual diseases really violates both conditions. These three violations constitute a violation of the first condition because they directly lie about sex itself. If two partners consent to sex, they must have sex, anything other than sex violates informed consent. In any case, Mappes lists some, but we can imagine more scenarios, how specific and/or explicit the consent should be is vague. Beyond the scope of sex itself, it is difficult to extend any further consideration to what is relevant. When both partners consent, what exactly are they consenting to? It is not possible for them to consent to everything during and after sexual intercourse and to everything that may even strictly concern the decision-making process. Condition two dictates that we must not threaten and coerce otherwise the sex is not voluntary and therefore permissible. This condition is obvious; harming another person is immoral. Coercive offers, however, do not meet this criterion. Considering case 6 (Mappes, 240), Mappes simply assumes that in case of refusal the professor would abuse his authority and take revenge against the student because his offer is an implicit threat rather than a verbal one. But again this is a big assumption on Mappes' part and doesn't follow. Therefore, only a threat is a violation of voluntary consent. Taken together, as long as the people involved consent and the two (modified) conditions are met, there can be no objection to casual sex, sex with strangers or prostitution and the like. Sex is still not allowed unless it occurs between two consenting adults and/or one or two conditions are violated: sex with children, rape, bestiality, to name a few. I now turn to Howard Klepper, who argues that informed, voluntary consent is not sufficient for permissible sexuality. According to Klepper, we are morally obligated beyond mere consent and therefore must respect our partners during and after sex. Klepper argues that sexuality is permissible, we must.