What is the point and purpose of public art? Once, it was clear: you were a general or an admiral and if you won a big enough victory you got a bronze statue stuck on a plinth. Or, if it was a very big victory against those dastardly neighbours, the French, you would even get a 151-foot granite column in Trafalgar Square. Nationalism was the point, or, in the case of Charles Sargeant Jagger's Royal Artillery Memorial at Hyde Park Corner or Great Western Railway War Memorial in Paddington railway station, a dignified commemoration of the dead was.
Today, in a democratic age, everyone has an opinion to voice on public art, from the cogno scenti to Joe Bloggs complaining about the waste of public money. Anyone who "knows" about art is likely to take the long route to avoid the horrendously kitsch and overblown Meeting Place at St Pancras Station, but who is to say that hundreds of ordinary people don't love it and use it as north London's version of Waterloo's celebrated clock?
And what about those ubiquitous Antony Gormleys that filled the skyline over the South Bank recently or which stare wistfully out to sea from Crosby Beach in Liverpool? Do you love them or hate them? As if there weren't enough "Gorms" around already, there is Angel of the North, and everyone has an opinion on that; from fascistic and bombastic to imaginative symbol of place. Take your pick.
Now we are to get what has been called Angel of the South, a £2m project sited on the new Ebbsfleet development in Kent. The towns of Dartford and Gravesham in the Thames Gateway are the scene for Britain's most ambitious attempt to establish pioneering sustainable communities around Britain's new international Eurostar station.
More than 20,000 new jobs and 10,000 homes are planned. This area of deprivation, which is neither city nor country, has until now largely been forgotten. Art is seen as a symbol of regeneration. Everywhere wants its own version of Frank Gehry's Guggenheim that changed the fortunes of Bilbao. The shortlist here is comprised of five artists: Rachel White read, Christopher Le Brun, Richard Deacon, Mark Wallinger (the favourite) and a token Frenchman, Daniel Buren.
And what is each artist proposing? Daniel Buren's idea is probably the most ambitious - a signal tower of five stacked cubes through which a single laser beam of light reaches indefinitely into the sky. The work does not seem quite right for this rather ordinary site adjacent to the A2, even though it would look wonderful on a hill or in an empty plain with a long approach. Richard Deacon's painted steel latticework, a "stack" of differently shaped polyhedrons, certainly echoes the skeletal frames of the nearby electricity pylons, bringing notions of engineering and geometry to a rural location, but seems a bit intellectual to sit in a field.
Christopher Le Brun has always made work that refers to myth. His disc and giant wing are symbolic of flight, reminding those who mind about such things that the winged Mercury was the god of both travellers and commerce. Made from concrete - one of the principal products of this part of north Kent - it would be made by first carving the shape into the chalk landscape and then casting the negative spaces in the chalk in concrete; the piece would create a giant grassed amphitheatre. Rachel Whiteread's proposal is rather disappointing, from a usually imaginative artist known for casting the interior spaces of domestic objects and places. Her life-size cast in terior of a house placed on a craggy "recycled mountain" is, in many ways, just a reiteration of the house she made in the East End of London in 1993, and seems too dour for this site.
So that leaves Mark Wallinger's enormous white horse, which probably presses all the right buttons. Witty enough to appeal to the cogno scenti and redolent with associations of Anglo-Saxon chalk white horses, it is also easy enough on the eye for the average person not to have to ask: "Is that art?" Thirty-three times life size, it will certainly function as a landmark and provide the logo that the developers of the site probably want. In the interests of democracy, those attending the nearby Bluewater shopping mall will be given the chance to comment on the selection (though they won't have any real power to influence the outcome).
But the real question is: Does public art always have to be monumental and so expensive? Some of its most effective uses have been modest - in hospitals and schools, for example. Andy Golds worthy, with his Lower Manhattan memorial to victims of the Holocaust, worked eloquently with nature's most elemental materials - stone, trees, soil - to create a garden that is a metaphor for the tenacity and fragility of life. The work of Peter Randall-Page integrates people with their surroundings and nature in order to convey a strong sense of place. Always precisely and quietly sited, it provides a deep connection to a locality through the use of organic forms.
I was commissioned during a residency as the Poetry Society's Public Art Poet to create a poem in the underpass at Waterloo Station that leads to the Imax cinema. The purpose of this piece was simply to make people feel comfortable walking through a urine-soaked, subterranean tunnel. Mark Wallinger's work, if it wins the Ebbsfleet competition, will provide a focus, a logo, a brand. But public art at its most effective can be both more modest and more reflective. At its best, it changes our relationship to a space and our feelings about how we inhabit it.