Last week, a 27-foot-wide, 2 1/2-ton bronze spider was installed on a sidewalk next to the Embarcadero.

Which means it is time for that old debate - is that art?

Because, for a group that is supposed to embody liberal values, San Francisco residents have a surprisingly timid view of large public statues. They may not know art, but they know what they DON'T like.

"I have always thought that it was an unusual irony," said Jill Manton, who has been the city's public art director for the past 17 years. "For such a progressive city, we are so conservative about our public art."

In the past 10 years, the list of projects that have been turned down by amateur art critics runs from the top of City Hall to the foot (literally) of Market Street. They even turned down a peace symbol for the Panhandle of Golden Gate Park, for God's sake.

"Some people said that, at certain hours, the reflection of the sun would cause accidents," said Tony Labat, a San Francisco sculptor who saw his 30-foot, stainless steel peace symbol proposal killed in 1999 by neighborhood opposition. "They said children would get their heads stuck in the statue."

The big bronze spider is in no danger of being removed, of course. The creation of Louise Bourgeois, the work is technically only supposed to be displayed for eight months, although Mayor Gavin Newsom said, with a wink at the dedication last week: "Sometimes we forget to take them away, and nobody calls to complain."

But besides avoiding the hassles of public hearings that are needed for a permanent sculpture, the spider has other advantages. It is by a world-renowned artist, it is an acclaimed work, and it is actually very cool. The way the immense insect balances on pinpoint feet (do spiders have tiptoes?) makes the structure look light and alive.

"I actually thought it might be yucky," said Jeannene Przyblyski, a member of the city Arts Commission. "But when you get close to it, it's not."

OK, but what would you think of it if it had been mounted on the dome of City Hall? That was a proposal back in the late '90s by Stanlee Gatti, who was then president of the Arts Commission.

"That was actually a little tongue in cheek," Gatti said Friday. "It was a thing that just came out of my mouth, and then afterwards I thought, 'How cool would that be?' "

Maybe so, but it was the sort of offbeat idea that made the locals gasp and helped Gatti decide to resign after a turbulent nine-year term in 2004.

"Well," Newsom said of the spider on the dome idea, "that was a little too much, too soon."

But it should be made clear that Newsom is wholeheartedly, enthusiastically on the side of the edgy and experimental.

"I don't like this kind of art," he said, gesturing to the spider. "I love it."

Really? A wonky, stat-spouting, political junkie like Newsom is an art buff? Absolutely, he said.

"I'm left-handed and dyslexic, for God's sake," he said. "I have to be interested in art."

Um, OK. But he's not kidding. He not only likes the spider, and supported the peace symbol, he was a supporter of one of the great dustups in recent San Francisco art history, the famous foot of the Embarcadero in 1997.

A concept piece designed by Seattle sculptor Buster Simpson, it really was a foot - 18 feet high and made of stainless steel. Not only was it one of those oddball pieces that induced eye-rolling from the general public, it wasn't cheap. The story goes that when then-Mayor Willie Brown called it "a $100,000 foot," Simpson was quick to correct him.

"It's a $500,000 foot," he said.

Gatti recalls a city official telling him, "I hate it. It is the stupidest thing I have ever seen."

The foot became a national punch line for San Francisco. Gatti recalls that the controversy was on Comedy Central, and Manton remembers going to a Board of Supervisors meeting and hearing a member ask, "Whatever happened to statues of men on horses?"

Depending on your point of view, the foot fuss either cemented San Francisco's reputation as a trendy city that nonetheless is afraid of art or restored common sense to the debate.

Then the issue was further confused in 2002 when Gap founder Donald Fisher paid for "Cupid's Span," the Claes Oldenburg sculpture that is just down the Embarcadero from where the foot was going to be installed. The cartoonish bow-and-arrow construction is appreciated by some, but many other art fanciers do not think much of it.

"I don't like it," Newsom said. "I never have. And I've told Don Fisher that."

There was a pause while everyone contemplated how that was going to look in the newspaper - the art-loving mayor knocking one of the biggest public art pieces in the city.

"And," Newsom added diplomatically, "I like that I don't like it."

Because isn't that what art is supposed to do, provoke a reaction? Of course, in San Francisco, that's never been a problem.