James Randi will do anything to debunk a superstition.

"I'd do a limbo under a ladder, stark-naked and on fire, if that's what it takes," said the internationally known magician.

"But," conceded the 80-year-old Randi, "I'm not as attractive as I once was. So I don't think there's much demand for that anymore."

For decades, Randi has gone to extraordinary lengths to inject rationality and a bit of skepticism back into American life.

Best known as the "Amazing Randi," a frequent guest on television talk shows, he also runs a Fort Lauderdale-based foundation that promotes critical thinking and challenges paranormal claims.

So it shouldn't come as a surprise that he's leaving his house this morning to travel to Philadelphia.

Tonight, Friday the 13th, Randi will be the guest of honor at the Freethought Society's "Anti-Superstition Party" at the Radisson Plaza-Warwick Hotel.

"I'm summoning up my courage. I'm going to conquer my fears," said Randi, tongue firmly planted in bearded cheek. "I've been promised nothing bad will happen to me . . . at least in the first half-hour."

When the Anti-Superstition fete was last celebrated in 2006, hundreds turned out to break mirrors, dance indoors with open umbrellas, and, yes, limbo under ladders.

"It's not just about overcoming Friggatriskaidekaphobia," said party hostess Margaret Downey.

Frigga-wha?

The 23-letter mouthful means "fear of Friday the 13th," she said, then continued.

"It's also an opportunity to show that most superstitions are based on illogical thinking," said Downey, who attends the fetes dressed as a nurse and dispenses certificates to partygoers graduating them with "A Clean Bill of Mental Health."

Friggatriskaidekaphobia is probably the most widespread superstition in America, according to Beliefnet.com, a popular religious Web site.

There's a serious mission for the party as well, Downey said: American's morbid fear of Friday the 13th has a dire impact on society.

"It has a huge effect on our economy," Downey said, citing a 1994 study that claimed $800 to $900 million is lost in business on Friday the 13th.

"Many people don't buy houses, get married, take trips or invest in the stock market simply because it's Friday the 13th," Downey said. "We think that should be stopped. It's just like any other day."

Michael Shermer, columnist for Scientific American and author of

Why People Believe Weird Things

, was the guest of honor at the 2006 Anti-Superstition Party.

"I don't think that many people take Friday the 13th too seriously," Shermer said. "But the party is proof that skeptics can have fun."

Humans are superstitious creatures by nature, Shermer said.

"It's a form of pattern-seeking behavior," Shermer said. "Once you get in your mind that something is real, it becomes a trigger for the confirmation bias. You look for - and find - evidence that confirms your belief. You remember the hits and forget the misses."

When Friday the 13th comes to an end, people will remember anything unusual that happened to them, Shermer said.

"But unusual things happen every day," he said. "We just don't notice them."

More Information

The Anti-Superstition Party, open to the public, runs from 7 p.m. to midnight at the Radisson Plaza-Warwick Hotel, 1701 Locust St. Donation: $10. Free for children under 13. For more information:

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Contact staff writer Sam Wood at 215-854-2796 or samwood@phillynews.com.