The difficulties the western tradition has had with sexual desire are spectacularly voiced by Kant: ‘Taken by itself [sexual love] is a degradation of human nature; for as soon as a person becomes an object of appetite for another, all motives of moral relationship cease to function, because as an object of appetite for another a person becomes a thing and can be treated and used as such by every one’ (Lectures on Ethics). Kant seems to be describing a gang rape rather than sexual love, but he thought the only, fragile, escape from the fate of being ‘cast aside as one casts away a lemon that has been sucked dry’ was a contractual relationship based on marriage, although he himself did not try it (nor, probably, sex). In Plato, sexual desire is a good, although only the first step on a ladder of perfection (see beauty, love, Dante). The movements of thought whereby Plato’s view degenerated to the Calvinism of Kant include increasing disgust with merely material as opposed to spiritual existence, and the Pauline and Augustinian conviction that original sin is somehow associated with sexual desire (see concupiscence). But older classical and Judaic traditions also associated sexuality and especially female sexuality and menstruation with uncleanliness and pollution. Women came off worst in other ways also, since as in too many modern cultures, rape was thought to dishonour the victim.

A more optimistic view of the matter than Kant’s was voiced by Hobbes: ‘The appetite which men call lust…is a sensual pleasure, but not only that; there is in it also a delight of the mind: for it consisteth of two appetites together, to please, and to be pleased; and the delight men take in delighting, is not sensual, but a pleasure or joy of the mind consisting in the imagination of the power they have so much to please’ (Human Nature, ix. 10). In this area, prophecies are apt to be self-fulfilling: it is predictable that if we side with Kant our sexual relationships will be a lot worse than if we understand Hobbes. The power of the tradition of sin is still visible in the ratio of writings that pay serious attention to Kant’s view, as opposed to ones that start with Plato, or Hobbes. See also obscenity, pornography.