The interrogation of the nature of art objects, and an implicit mistrust of artworks as commodities, has been a major theme in the art of the present century. With its robust assertion of the idea over the object, of thinking over craft, American Conceptual Art of the 1960s was but one example of this unease. Presently, in the work of the youngest generation of British artists, ideas may be small and objects may be abject, but the spirit of Sol LeWitt's 1969 Sentences on Conceptual Art still inform even the most throwaway work. "When an artist learns his craft too well he makes slick art," he wrote. And "Illogical judgements lead to new experience". LeWitt, by and large, has been a supremely logical and systematic artist, yet he has always known that at heart, art is unquantifiable and subjective. "Conceptual artists are mystics rather than rationalists. They leap to conclusions that logic cannot reach," stated LeWitt, though logic might tell us that some conclusions aren't worth reaching, and although "Ideas alone can be works of art" they'd better be interesting ones. Slightness, of course, can easily be mistaken for transcendence.
While Conceptual Art was, as much as anything else, a reaction against the lumbering postulates of late Modernism and the implacable blankness of Minimal Art, it shared much with them. The Minimalist sculptor Carl Andre, for example, also wrote poems which can be read in the same spirit as LeWitt's aphoristic sentences, and if the sculptor Richard Serra's early actions and films are precursors of much "body art" and Performance work, they also share the Conceptualist belief that ideas and objects are not the same thing.
"Big, egocentric, expensive works become very imposing. You can't put 24 tons of steel in the closet," the American Conceptualist Lawrence Weiner, once remarked. Weiner's short, anonymous statements are themselves intended as a kind of sculpture, albeit one which his audience is meant to construct in their heads. Conceptual artists don't need overheads like studios, paints, assistants. That the well-crafted object is not the be all and end all has been a lesson well learned by the generation of artists growing up in the Nineties, who forego the luxury of studios and the production of well-crafted objects. Conceptual Art can be made on the dole.
In 1970 John Baldessari burned all his paintings made between 1953 and 1966. This strategy, which I wholeheartedly recommend to many painters, was, in his case, a ritual act of purification, signalling his rebirth as a Conceptual artist. The cremation was advertised, photographed, documented, and the ashes are kept in a little urn, which now sits on a shelf in his Serpentine Gallery retrospective.
One reason he gave up painting was, he said, because he had no audience, and that, living near Hollywood, painting seemed somehow irrelevant. But, it strikes me, Baldessari's refutation of painting may have more to do with the fact that Southern California is too damn hot for such energetic work. Even before he torched his oils, Baldessari had taken to writing gnomic statements, which he had transferred on to canvas by a signwriter: "Pure Beauty", they read, and "Everything has been purged from this painting but art, no ideas have entered this work". But for Baldessari, the purging of everything from his art, was too much. Time hangs heavy, for the Conceptualist who's gone too far. He needs a life.
I imagine Baldessari, lounging behind the closed blinds in sunny Santa Monica, watching re-runs on TV, flipping through glossy magazines, raiding the fridge and generally having a nice lie down. His art, over the past 25 years, has come to reflect this, with its scrapbook paste-ups of fragmented, stolen imagery: back-lot B-movie cowboys, femmes fatal and Babewatch beauties, wildlife shots, sportswear Jocks, palm trees and rainbows, the base material for his afternoon-shift adventures with scissors and glue. Nowadays, his art is all loose connections, skewed collisions and out-takes, chaotic situations, short-term memory lapses, blank spaces, mushy blobs and lot plots: a California of the mind.
Fellow Conceptualist Joseph Kosuth once called Baldessari "Papa", in acknowledgement of his role in the movement. Labels tend to stick, but Baldessari isn't certain whether he's a Conceptualist any more. Nor, on the evidence of his Serpentine show, is he a slouch: his work is livelier, more youthful and more fun than that of many artists a third of his age. At times, it is even profound. If Conceptual Art was founded on the denial of the visual in favour of the cerebral ("Live In Your Head" was the subtitle to one early 1970s Conceptual show), Baldessari's art is not Conceptualist at all: it is a riot of images.
Once, Conceptual Art dealt with an object that had vanished. As the painter Al Held said, "it was nothing more than just pointing at things". It was funny, infuriating, mind-boggling, pretentious, hectoring and difficult. But, if Conceptual Art could be bad poetry and, worse, amateur philosophy, it could also point to the relationships viewers have with artworks, and the relationships artworks have with the rest of the world. If Baldessari was the Godfather of Conceptualism, Duchamp was its Grandpa, and the influence of his ideas, and his mistrust of "Retinal art", and "Olfactory art" (a term he used to deride oil painting, because you could smell it) has led to an increasing self-consciousness on the part of artists about the media they use and the things they want to say with them. Baldessari's art may, in the long term, be seen as minor, local phenomenon, yet his lesson, like that of the Conceptual movement as a whole, has been to free up the territory for making new kinds of art, and for thinking about art in broader terms.
n John Baldessari, continues at the Serpentine Gallery until 28 August. Admission is free. Tel: 0171-723 9072