The first thing you encounter is a ballot box bolted to the lid of a school desk; what or whom you might be voting for – apart from the hope of change – is not specified. In the eyes of Jimmie Durham, change is badly needed; in fact, most of the premises on which western society is built could do with a radical rethink. Judging by the state of the box, though – the lid looks as if it has been prized open and bolted down many times – fair and free elections seem unlikely. Mostly probably, the outcome would be rigged.

I’ll admit, there's a scene that made me well up during the excellent Marina Abramović biopic The Artist is Present. If you've seen it you’ll know the scene I mean – it’s where Ulay, Abramović’s former partner, in art and in life, takes the seat opposite her on the last day of her MoMA marathon performance. And the tears come, hers and his and then ours, and she takes his hands, and then more tears. Oh god.

Her name sounds like a brand of cigarettes, and an aura of corporate anonymity seems remarkably apt for this American artist who specialises in replicating other people’s work and sampling clips from online video libraries.

On the evidence of this Serpentine exhibition of huge sculptures, small sculptures, photographs, drawings, watercolours and prints, the German artist Thomas Schütte is obsessed, but obsessed, with faces. It is billed as the first show to focus entirely on his portraiture, of himself, his friends, and from the imagination. And the focus helps the visitor to grasp how playfully serious – or seriously playful – the artist is.  

Oh yes, I remember it well. Luise Kimme, a German sculptor who shared my flat in the early 1970s, used to buy plaster copies of Michelangelo’s David, paint them garish colours and give them to friend as presents. More a conceptualist than a lover of kitsch, I meanwhile set projects for my students requiring them to photograph every item of clothing in their wardrobes or to empty their bags and present the contents as self-portraits.

The Serpentine’s north gallery has been transformed into a magical space (main picture). Strung from floor to ceiling of the darkened room, shafts of copper wire glimmer in subdued lighting like sunbeams, or the searchlights that scanned the night sky for enemy aircraft during World War Two.

A single snare drum greets you on entry to the Serpentine Gallery; there’s no one playing it, yet in response to an inaudible cue, the drumsticks begin to vibrate autonomously. Meanwhile on a nearby wall, a pair of blue rubber gloves revolves slowly as if searching for something; every now and then they take on the shape of human hands, as though embodying the gestures of the absent drummer.

A sliderule of 11-15 per cent reductions in annual grants by 2015, compared with this year, has been applied to Britain's major orchestras, opera, dance, theatre and music organisations. One major gainer is London's Barbican Centre - one major loser is the now world-famous Almeida Theatre, which loses almost 40 per cent of its current annual subsidy despite its reputation for innovation and discovery. However, the Arcola Theatre, another small innovative theatre, gets a big boost. Companies to lose all their grant from next year include Hammersmith's Riverside Studios and Derby Theatre.

It takes a lot of work to make a show look as unconsidered and chaotic as this one: thought and care and time and attention all have to be paid before something so random can be achieved. But as so often with Tillmans, the nagging questions persist: is randomness, are the offhand and the casual, valid as ends in themselves? Because Tillman’s über-hip affectless cool has become very tiresome indeed. Even worse, it’s becoming predictable and dull. Tillman's eye, as ever, remains wonderful, but I remain doubtful about the form in which he chooses to convey his ideas.

Sir Frederick Ashton, Britain's unrivalled genius at creating ballets, had a simple attitude towards posterity. "You've heard his famous remark, 'Fuck posterity'?" says his nephew, Anthony Russell-Roberts, smiling but eyeing me apprehensively.