Beauty is a problem. It is as confusing as it is inspiring. Never mind a thousand ships, it has launched a thousand arguments. People have written about beauty since Plato mused about ideal form and told us to admire spheres. But he also knew how fascinating atrocities can be: rotting corpses piled beneath an executioner's dais were at least as interesting as the serene proportions of a classical Athenian temple.
The Italian photographer Oliviero Toscani exploited this shocking idea 20 years ago. Fatigued by the politeness of fashion advertising, he produced deliberately aggressive adverts for Benetton. Today, Riccardo Tisci has used goth iconography of the undead to bring life to the tired Givenchy. Ugliness has its place.
The fact is, in Plato's ideal republic, then or now, to appreciate beauty, you need a concept of ugliness, possibly even a positive appreciation of it. And if you accept that argument, it follows that ugliness is a good thing. So does that mean we need to encourage a measure of ugliness to maintain civilised standards? If yes, exactly how much ugliness do we need? More and more, as the growing success of the Ugliest Dog in the World contest, held in California, suggests. This year, it was won by a Chinese crested dog, a breed whose distinguishing characteristic is a repellent hairlessness.
So, if a measure of ugliness is good for us, it also has other useful attributes acknowledged by culture. "Ugliness," the gargoyle-like Serge Gainsbourg once said, "is superior to beauty because it lasts longer." Like Marcel Proust, he agreed that a taste for ugliness was aristocratic, because it suggested a disdain for wanting to please people.
Ugliness can, perversely, be attractive. In London's National Gallery, there is a splendid portrait by the 16th-century Flemish painter Quinten Massys. It shows a middle-aged woman, her skin like an old leather saddle, suffering from a bone deformity that has turned her skull into a misshapen grotesque. This hideous monster was the inspiration for Tenniel's ugly Duchess in Alice in Wonderland, the stuff of nightmares for many of us. Yet the postcard of the painting is one of the most popular in the National Gallery's shop. In terms of popular appeal, an ugly old woman rivals Monet's sweetly bland water lilies.
The concept of jolie-laide, popularised by Nancy Mitford, recognises our curious equivocation between attraction and repulsion. Translated, jolie-laide means "pretty-ugly". It sounds absurd, but there are women - men, too - whose features are imperfect, even awkward, angular and aggressive, but who remain mysteriously beautiful. Jeanne Moreau, Isabella Blow, Diana Vreeland, Coco Chanel, Edith Sitwell and Mitford herself are all historic examples.
And, while women may be manipulated by the fashion system to perform contortions in pursuit of an abstract notion of beauty, men are no less vulnerable to aesthetic pressures. The classic gentleman's wardrobe is an intimidating aesthetic straitjacket. And ugliness plays its part in male attraction. Or have you not seen the simian Jean-Paul Belmondo and the labially intrusive Mick Jagger?
Beauty and ugliness are not opposites. They are part of the same thing: it's called aesthetics. This is more than a branch of philosophy, it's an attitude to life itself. And the big lesson from aesthetics is: be cautious about making judgments. In both art and fashion, convictions are subject to continuous reappraisal. If beauty is not permanent, then neither is ugliness.
Ugly: The Aesthetics of Everything by Stephen Bayley (Goodman $49) is out now.
