Lust has for too long been unfairly maligned. Far from being a sin, it should be celebrated as a virtue, argues Simon Blackburn

When, 18 months ago, I was asked to give a public lecture on one of the seven deadly sins, in a series mounted jointly by the New York Public Library and Oxford University Press, several sins had already been bagged.

I was offered the choice of sloth, anger or lust. Each was tempting, and each had a good philosophical pedigree. But I felt immediately that only lust had star quality.

I had scarcely accepted when I became aware of my disqualifications as a middle-aged (at best) academic, male, heterosexual English grandfather.

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Practically a paid-up member of the patriarchy, how could I move a step without outraging feminists, queer theorists, victims and campaigners for victims - people of every hue? I saw myself driven from the stage for using the wrong pronoun, let alone making the wrong joke. I saw armies of therapists offering me help.

And what should I expect from the New York audience? To the English, the American penchant for sharing a bed with each partner's lawyers, and after that with Jesus, feels uncomfortable. Five is a crowd, and we would be embarrassed, or even unmanned, by a ghostly audience distracting us with whispers of legal and religious proprieties.

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And then there was the fate of my distinguished predecessor, Bertrand Russell, who in 1941 was stripped of his appointment at the college of the city of New York. After a macabre witchhunt, he was dismissed on the grounds that his works were "lecherous, libidinous, lustful, venerous, erotomaniac, aphrodisiac, irreverent, narrow-minded, untruthful and bereft of moral fibre".

Professionally, I was also nervous of being overlooked by armies of experts in other fields. Pharmacists design drugs to modify lust, doctors describe its malfunctions, neurologists plot its cerebral stirrings, social psychologists set questionnaires about it, evolutionary psychologists ponder its origins, postmodernists deconstruct it, and feminists shake their heads over it. A large part of the world's literature is devoted to it or to its close relative, erotic love.

So I had to think of myself as no more than taking a philosophical stroll in the park, here and there stopping to point out an interesting view. The park, I argued, is not a paradise. Weeds grow, serpents lie in wait, and people have built slums over parts of it. But we do not have to inhabit them, if we are careful. My general thesis was to be that lust should be shifted from the category of "sin" to that of "virtue". David Hume defined a virtue as any quality of mind that is useful or agreeable to ourselves or others. Lust qualifies in spades. But my leading witness was the philosopher Thomas Hobbes, who said: "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."

I contrasted Hobbes favourably with Kant, who paints an unhappy picture in which lust objectifies the other person, using them as a mere means, a tool of one's own purposes. It is dehumanising and degrading, and, according to Kant, it is morally forbidden because you may never use another person as a mere means to satisfy your own ends. In this account, the other person is reduced to an assemblage of body parts, and indeed Kant calls marriage a contract for each to use the other's genitals, making it lucky that he never tried it.

Although in philosophy many writers, including Thomas Nagel, Roger Scruton and Robert Solomon, have worked with Hobbes' approach, it is a sad fact that in the culture in general more people seem swayed by Kant. Yet Kant gives us what might fairly be called an obscene or pornographic view of lust, removing the accompanying consciousness and turning what should be a fully human interchange into a manipulative set of jerks and squelches.

To shift our perception of lust, I also enjoyed contrasting the standard Platonic story of ascent, whereby lust for sex with an individual gives way to an abstract love of beauty, with the more earthy Shakespearean view in which erotic love is the domain of unreasonable dotings, fiction, madness, bubbles, blindness and illusion. It is not obvious why we ought to prefer the latter: indeed some writers have associated the illusions of love with blindness to the real nature of the beloved, who becomes merely a cardboard prop for a personal fantasy. This is the dreaded objectification under a different guise, and it would seem to make it at least an option that we ought to take our lust neat.

Lucretius and Epicurus were proponents of that preference, each of them believing that if you feel love coming on, the best remedy is to go and have sex indiscriminately with whomever you can until the fit passes. But Hobbes stands in the way of this solution because, in such encounters, the reciprocal consciousness of delight will almost inevitably be a pretence.

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In the event, the New York audience was marvellous: civilised, humorous, open-minded and everything else that ignorant people suppose Americans are not. They were on my side when I showed a slide of the Botticelli of Mars and Venus that hangs in our National Gallery, and I pointed out that it is much preferable to have the god of war stretched out in post-coital languor while putti play with his weapons, than to have him donning his armour and chucking his weight about. They were also pleased with Schopenhauer's famous remark that lust "does not hesitate to intrude with its trash, and to interfere with the negotiations of statesmen and the investigations of the learned. It knows how to slip its love-notes and ringlets even into ministerial portfolios and philosophical manuscripts". They readily saw both this and the Botticelli as prophetic of the Clinton presidency.

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Of course, one cannot classify lust as a virtue without some qualification.

So my principal illustration was more complex, although also more titillating: the splendid Bronzino allegory, also from our National Gallery. Here is lust incarnate and at its best, as Venus returns Cupid's wanton caress by tonguing him with such obvious surprise and delight. But well before it came to London in 1860, someone had added a veil over Venus's pudendum and a myrtle bush over Cupid's rather prominent buttocks (reversing Bronzino's own journey, since his own late changes had been devoted to increasing the erotic content). When it was purchased, it was considered sufficiently disturbing that Sir Charles Eastlake, the director of the National Gallery, had Venus' probing tongue and Cupid's nipple-tweaking fingers painted over. It was not until 1958 that the painting was restored to its original state, just in time for the Swinging '60s.

Although the portrayal of lust is itself delicious, it is also true that the bad things that surround lust are here in force, quite apart from the regrettable fact that Venus is Cupid's mother. For Venus holds the apple of discord, which lust or love brings equally into the world. In the background is blind Fate, or Fortuna being revealed by Time (fortune is blind somewhat as Cupid usually is, because she rewards the bad and torments the good). Joy or Delight strews roses on the amorous couple. Yet just behind Venus is Deceit with her fair face and her honeycomb of pleasure, but also her serpent's tail. Tearing his hair there is Anger or Jealousy. And in one of the most significant, although almost invisible, touches, the rose-strewing Joy or Delight is treading, without noticing it, on thorns. Well, one can't have everything.

Writing up the lecture for publication proved surprisingly difficult.

Academic philosophy, let alone theology, is no friend to the light touch, and at times it seemed hard to bear the relentless disapproval of Augustine, Aquinas and Kant. There were also the knotty problems of lust gone awry, in all the dark corners of the rag-and-bone shop of the heart.

Eventually, however, the forces of Hobbes beat the Christians and Stoics, and even Sartre (who thought lust was largely a matter of abolishing the gaze of the other person). There is no Hollywood ending, but on the whole humanity does not come out of it too badly.

Simon Blackburn is professor of philosophy at the University of Cambridge.

Lust is published by Oxford University Press on February 5, price ?7.99. It is the third in a series on the Seven Deadly Sins.

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