Le Corbusier was, arguably, the most influential architect of the 20th century. Every time you walk past the Barbican, you're in Corbusier territory; the same applies if you explore the ruins of the extraordinary seminary at Cardross designed by Gillespie Kidd & Coia, or if you happened to be strolling through the Sussex University campus designed by Sir Basil Spence. Should you travel on a Virgin Pendolino to Liverpool, where the first major British exhibition on Corbusier's work for 20 years is underway, you will pass through a tranche of post-Corbusian urban planning known as Runcorn.
More than three decades after drowning while swimming off the coast of the Côte d'Azur, Corbusier's importance makes him almost impossible to discuss, or view, without lurching into prejudice. He saw the future and designed it decades before anybody else. Correction: he tainted the future with the allure of concrete, and surfaces stripped of texture or decoration. His designs proposed a sensually socialist world. No, he was an utter solipsist who wanted very little to do with people who weren't as over-dressed, bourgeois, creative and mother-fixated as he.
Le Corbusier, The Art of Architecture is embedded in the crypt of Liverpool Metropolitan Cathedral. And there's a nice conceit to this: the launch-pad architecture of the so-called Paddy's Wigwam was designed in the Sixties by a Corbusian, Sir Frederick Gibberd, but rose from a crypt designed by Sir Edwin Lutyens in 1931 as the foundation of a cathedral that would have been as big as St Peter's in Rome. Under those beautifully bricked vaults, in a show sponsored by the Royal Institute of British Architects and the Vitra Design Museum, should we bury architecture's Caesar – along with those heavy, circular spectacle frames that said: I see things you don't – or praise him?
The first thing to say about the exhibition, created by Graeme Russell, is that it has been arranged with considerable virtuosity. Russell, working with Dieter Theil, has deferred with some grace to Lutyens' marvellous spaces, yet managed to create thoroughly modernist sets: the tableaux and linked perspectives are precisely set out, and we are drawn through the show by subtle glimpses ahead at key points.
Perspectives relating to the fountainheads, and riddles, of Corbusier's art and architecture are less certainly portrayed. The genius of the Swiss architect is certainly apparent, but not in an obviously progressive narrative; we don't quite get to the root of his obsessions. Nor is there any subtext of humanity, or of humane architectural commodity. Corbusier's conflations of art and architecture are mostly presented as a kind of orderly collage or scenography in which time, or the critical moment, seems absent. The material in the three sections of the exhibition – Context, Privacy and Publicity, Built Art – often seem interchangeable. In this, the show reminds us just how brilliantly seductive, and ultimately ungraspable, Corbusier could be. "I am an acrobat of form, creator of form, player with form," he declared in 1951. "Form means to express all plastic emotion. Form, expression and style of mind." Architecture, he said, was "a pure creation of the mind".
Today, in an age of styled minds, and sanctified immateriality, the very idea of purity or formal playthings seems as museum-worthy as a Bakelite telephone. Corbusier still matters – not so much as an architect, but as an engrossing case-study of a designer who began by referring to houses as machines for living in (Huxley saw through that clinical nonsense in his 1932 satire on modernism, Brave New World), and ended in the thrall of primitive abstract art, not to mention breasts (drawn, on collected postcards, carved, concretised).
Most architects, even arch-modernists, think of themselves as artistic. They are not, but they want to be; a drawing board, computer screen or the now -virtually unused Rotring pen are ultimately Nanny Whips, rather than naked models. Corbusier was the first of the post-Bauhaus massive to bring arbitrary abstraction, and the body's sensuality, into major architectural works, and tens of thousands of ordinary architects have since tucked into that vaguely sexy design slipstream with no intention of pursuing the profound creative conflicts and risks that generate the best architecture.
The risk is that we should think of Corbusier's art and architecture as interchangeable. Fortunately, the exhibition demonstrates only juxtapositions between his art and architecture, rather than fusions. Architecture, however artful, is almost always extruded through a conflicting mesh of imagination, rationality, cost and functional imperatives. If you are Zaha Hadid, you will have clients who can pay for a vast sculpture in the Emirates that might also happen to be a concert hall; if you are Jacques Herzog or Rem Koolhaas, you can deploy outlandish amounts of steel to create a stadium or a state television headquarters in Beijing whose forms are perceived as being in some way artistic. But the art-response is mendacious and activates a pernicious trip-wire: architecture plus art equals entertainment; entertainment is fleeting, therefore architecture is fleeting and we needn't trouble ourselves to think too deeply about it.
Corbusier thought deeply about architecture – even the Edwardian Lutyens, who disliked his architecture, recognised this – and he designed and built for posterity. Even his models were built to last. The massive wooden model showing the artfully symbolised topography and buildings of the government site in Chandigarh, India, is utterly engrossing; its undulations and objects form a richly surreal tableau, a dreamscape rather than an architectural setting. In the mind of Corbusier, reality always follows dream.
Or almost always. The illustration of Corbusier's Plan Obus, a 1931 scheme that would have demolished two-thirds of Algiers' kasbah to make way for a continuous serpentine apartment block hundreds of feet high, several miles long, with a motorway on top of it, could be described as a "plasticised" primitive relief. In this case, art threatened architecture: a wonderfully revealing perspective drawing shows a single man standing on a narrow central walkway between the two lines of traffic, with the Gulf of Algiers far below. In one image, we see the brilliance and potential vacuity of Corbusier as the artist of a floating, ferroconcrete world that mostly wanted very little to do with the ground (messy) or people (ditto), and vastly more to do with cars and aeroplanes and houses such as the seminal Villa Savoye (which hardly touched the ground). The exhibition succeeds admirably in showing facets of this eternally debatable aspect of his architecture.
Obus means bombshell in French. Graeme Russell's exhibition has given us the shell fragments of Corbusier's architectural impacts, but not the tensions that underlay them. We encounter much that is of interest: films, models, carving, letters, magazines, fly-through visuals; and all of it set out to suggest fairly distinct connections between his art and architecture. Yet what really matters (and the exhibition avoids this important provocation) are the dynamics of their estrangements. The show proves, unintentionally, that Le Corbusier was – and in no small way – a great architect because he was a minor artist.
Le Corbusier: The Art of Architecture, is being shown in the crypt of the Metropolitan Cathedral of Liverpool, to 18 January (see www.architecture.com/lecorbusier for details)