Big Brother state: Ai Weiwei's "Surveillance Camera" (Lisson Gallery) 

Something troubles me about the Ai Weiwei affair. First, the artist victim. Victim he undoubtedly is, and a brave man, but more architect, designer, photographer and blogger than artist. For 12 years the well-born celebrity (his father was China's best-known poet) lived in New York. There he learned to play the conceptual game, a century-old style belatedly imported by British then Chinese artists, and is prolific in the high-toned vacuity of the genre. "After Duchamp I realised that being an artist was more about lifestyle and attitude than producing some product." Before the ready-mades Duchamp produced superb paintings, but never mind. And when his politicised blog is described as "social sculpture" in the manner of Joseph Beuys, Ai does not demur.

Emerging from his fellow-travelling phase, Auden pointed to the dangers of mistaking political gestures for art: "To do this is to reduce art to an endless series of momentary and arbitrary ‘happenings' and to produce in artists and public alike a conformation to the tyranny of the passing moment, which is far more enslaving, far more destructive of integrity and originality, than any thoughtless copying of the past."

Ai's Dropping a Han Dynasty Urn (1995), a stunt to show irreverence for antiquity, is actually a kind of copying too: as early as 1919 Duchamp painted a moustache and goatee on a photograph of the Mona Lisa. But then as Gore Vidal remarked, everything changes except the avant garde. It is not done to say it — having your political heart correctly positioned forestalls criticism — but Ai's works can be as lumbering in concept as they are laborious in construction. Endorsing a political sentiment does not oblige us to admire its supposedly artistic expression. "The work continues to pose challenging questions. What does it mean to be an individual in today's society? Are we insignificant or powerless unless we act together?" The Tate curator's words on his sunflower seeds fit the work perfectly. Like the "sculpture" itself they are ponderous, inflated, pious and banal.

One thing appears certain: that Ai's cosmopolitan status has already ensured treatment less harsh than the 11 years meted out to the Nobel Peace prizewinner and university lecturer Liu Xiaobo, a serious political thinker, though a non-celebrity.

The second false note concerns Ai's Western art-world supporters. There is something a little indecent about the link between      human rights in China and the commercialised showmanship of the contemporary art market. Consistency is not to be expected in these circles, but I do not recall the Western arts community making impassioned protests when the Chinese communists were    murdering millions. Under the regime so many of them championed, Ai would be long dead, rather than released on bail, and in many an arts-person nostalgia for the Mao-badge era lingers. Most phony of all of course is China's pretext for locking him up — tax irregularities. True, he has pleaded guilty and thereby earned release after less than three months. In a perverse sense they have little choice but to go for him. In the wake of the Arab Spring the country is undergoing one of its periodic spasms of reaction: images of crowded squares give the Communist Party the jitters, and they can hardly leave someone as outspoken and prominent as him at liberty while arresting so many others, of whom we hear so little.