Beauty is the most dangerous idea in art. It's the most dangerous idea in life, too. It tantalises and confuses, inspires and crushes. Beauty has been worshipped as the highest artistic value and denigrated as a pagan temptation. Today, though, it is simply treated by the art world as a joke, a con, an idiotic, old-fashioned idea. This makes much art irrelevant, because beauty is everywhere and obsesses everyone (whatever your idea of beauty happens to be).

Maybe this is why photography, professional and amateur, is the true art of our time. Photography has no objection to beauty. Photographers feast on fashion, delight in the desirable. Why are other art forms today so reluctant to do so?

Clearly, this is the result of a long intellectual process that began with modernism. Or is it? Enemies of modern art complained 80 years ago that the new art was ugly. They thought the distortions of Picasso were a hideous attack on the classical beauty of the human form as seen by the Greeks. They were wrong, of course: Picasso loved Greek art more than they did and his paintings and sculptures responded intensely to beauty. So, obviously, did Matisse. The Surrealists were obsessed with (strange) beauty. So when did official art stop being interested in beauty?

It must have been when modern art started believing its own critics. Told again and again that modernism was "ugly", the modernists defended themselves by arguing that beauty is a superficial, bourgeois value and true art is about ideas, politics, the sublime. At the same time, since the 1970s – since the silver jubilee, exactly 25 years ago, when the Sex Pistols were number one – the anti-art tradition of Dada has been mainstream. In the serious art world of today, all this comes together in a pretentious and totally inaccurate belief that radical modern art has always rejected the beautiful.

So, galleries are full of serious art that shuns beauty. And we look at it earnestly, then go and look at gorgeous photos, films, magazines – the true art of our time.