Hayward Gallery, SE1
If you really want to understand what Patrick Caulfield is about, try going through the Hayward Gallery's retrospective backwards. Start with one of the newer pictures - the deeply gorgeous Lunch-Time (1985) is as good a place as any - and count the number of different kinds of painting you can see going on on Caulfield's busy canvas.
Clearly we are in a room - a restaurant, maybe - whose vaguely Cubist walls are covered in something that may or may not be button-backed red velour. If we take this as a mid-point on Caulfield's sliding scale of figurative representation from abstraction to photo-realism, then the napery-pink wedges in the picture's lower half sit towards its abstract end. The wedges may be there to imply a light-source, or skirting boards, or bistro napkins, or they may simply be there because Caulfield thought pink looked good with red.
Some considerable way towards the other end of the Caulfield Figurative Scale is a photorealist geranium, levitating potlessly above a Pop Art table whose comic-book shadow falls upon one of the aforementioned wedges of pink. And dropping right off the realist end of the scale is the Whistler- ish little Japanese plate sitting on a shelf - all cherry blossom, kitsch kimonos and mirrored glaze - whose scrupulously drawn court ladies look down in alarm at the riot of representation taking place beneath them.
What is going on? For an answer, let us walk briskly downstairs to the first room in the Hayward's show, to a picture - Greece Expiring on the Ruins of Missolonghi, after Delacroix (1963) - painted when Caulfield was a student at the Royal College of Art. The artist's own explanation of how this work came about ("We were asked to paint a transcription of something of our choice and this was mine") is not entirely helpful. Clearly, his re-rendering of the painting as a Tintin cartoon - Caulfield's famous black outlines make a precocious appearance in the stone blocks of Delacroix's ruined city - is intended as some kind of statement.
More specifically, the junior Pop Artist seems to be raising two subversive fingers at classical ideas of representation. The oddly moralising message of Greece, etc - these were the Sixties, remember - is that the representing of three dimensions on a two-dimensional canvas by means of illusionist trickery is dishonest. Delacroix gulled his viewers into seeing the perspectival depth of stone blocks by painting their facets in gradated tones; Tintin's creator did so by outlining them in black and colouring them in. Replace one convention with the other (as Caulfield does in this picture) and the fakery of classical illusionism becomes clear.
He was not the first artist to have gone through such a stylistic crisis of conscience. Jacques-Louis David had a crise of his own when Rousseau, his philosophical hero, declared illusionism to be sinful. David only got around the interdict by painting pictures whose subjects made no pretence at all at realism - statuesque Romans striking impossible poses in theatrical spaces. Caulfield, more bolshily, spent his early career sniping at illusionism by turning classical subjects into cartoons. His Pony (1964) is a venomous piece of anti-Stubbs; the Mary Poppins-ish View of the Rooftops (1965) and Bend in the Road (1967) thumb their noses at the post-Victorian sentimentality of English painting in the generation before Caulfield's own. Somewhere in all of this there is an oddly Calvinist distaste for the connection between art, artifice and artificiality.
But look at View of the Bay (1964) on the next-door wall, and something else becomes clear. No matter how subversive Caulfield's intentions, he just can't help making his pictures look nice. View of the Bay may turn Matisse and Derain into comic strips by pushing Fauvism that little bit too far - red boats are merely red, yellow windows yellow - but the painting is still curiously beautiful. For all Caulfield's snook-cocking at tradition, there is something irrepressibly old-fashioned about his sense of colour and feel for form. Whatever his moral reservations about painterliness, he just can't stop being painterly.
Fast-forward 10 years - and a few rooms on in the Hayward's show - to Paradise Bar (1974), and this tendency becomes even more apparent. Caulfield's earlier work defined itself by reference to other art, but here it finds a milieu all of its own: the kind of popular eatery from which the painter would seem not to have stirred for the last 25 years.
Far from rejecting the kind of trash culture these places imply, Caulfield's style embraces it with relish: plastic grapes and plaid banquettes need to be drawn as comic strips, and that's just what he does. There are two particularly impressive things about Paradise Bar. The first is that its infra-red-strip-light-white palette and Beano-black outlines evoke the bar's hellish ambience with extraordinary vividness. The second is its inscrutability. Where does Caulfield stand on his subject? Is his eye satirical or fond? Are the endless cafes and wine-bars of his work vulgar or delightful? The Paradise Bar's Marie-Celeste emptiness makes it impossible to say.
That emptiness has also become a trademark of Caulfield's work. Pipes have remained unsmoked, telephones unanswered, food (quiches, paellas, pates, plates of Chicken Maryland) uneaten in his pictures for 35 years now. The artist's own explanation for the absence of people in his paintings - that "Picasso had pulled the plug on interpreting the human form" - is clearly hogwash. By eliminating the human form from precisely those situations in which we might most expect to find it - bars, restaurants, hotel foyers, dinner tables - Caulfield draws attention to the signs by which we know it should be there: the flock wallpaper, patterned carpets and Seventies dining chairs which will have Wallpaper* readers hugging themselves with delight. (Not for nothing is this show sponsored by Habitat.)
The perverse thing about all this is that the young painter who had such problems with artifice has turned into a middle-aged painter besotted with artificiality. Walk back to Lunch-Time (1985) and you will see where all of this has been leading. Where once Caulfield looked on prawn-cocktail chic with an impassive eye, his absorption in it has now become complete. His late paintings are no longer about the forensic reproduction of other people's patterns. They are about using those patterns - Japanese plates, button-backed red velour, pink napkins - to generate patterns of the artist's own.
Somewhere along the line, Caulfield has stopped painting pictures which are merely about other people and has begun to paint pictures about himself. Give him another 20 years and you feel he may be doing abstracts: I look forward to seeing them.
Hayward Gallery, SE1 (0171 928 3144), to 11 April. The Alan Cristea Gallery, W1 (0171 439 1866) is showing Caulfield's prints until 13 March.