“These things used to be on the back of cornflakes boxes,” Mr. Randi, his voice italic with derision, once told the television interviewer Larry King. “But apparently some scientists either don’t eat cornflakes, or they don’t read the back of the box.”
The recipient of a MacArthur “genius” grant in 1986, Mr. Randi lectured worldwide and appeared often on television; he was a particular favorite of Johnny Carson and, more recently, Penn and Teller.
He wrote many books, among them “Flim Flam! The Truth About Unicorns, Parapsychology, and Other Delusions” (1980); “The Faith Healers” (1987); and “An Encyclopedia of Claims, Frauds, and Hoaxes of the Occult and Supernatural” (1995).
In 1976, with the astronomer Carl Sagan, the writer Isaac Asimov and others, Mr. Randi founded what is now the Committee for Skeptical Inquiry. Based in Amherst, N.Y., the organization promotes the scientific investigation of claims of the paranormal and publishes the magazine Skeptical Inquirer.
Though he was often called a debunker, Mr. Randi preferred the terms “skeptic” or “investigator.”
“I never want to be referred to as a debunker,” he told The Orlando Sentinel in 1991, “because that implies someone who says, ‘This isn’t so, and I’m going to prove it.’ I don’t go in with that attitude. I’m an investigator. I only expect to show that something is not likely.”
In the course of his career, he investigated more than 100 people, including, memorably, Peter Popoff, a well-heeled self-described faith healer whom he exposed on “The Tonight Show.” Mr. Randi was also known for his decades-long sparring match with Uri Geller, the professed mentalist known for his serial abuse of flatware.
Through the James Randi Educational Foundation, Mr. Randi sponsored the Million Dollar Challenge, a contest offering $1 million to the person who, following rigorous scientific protocols, could demonstrate evidence of a paranormal, supernatural or occult phenomenon. Though the challenge attracted more than a thousand aspirants, the prize remained unclaimed on Mr. Randi’s retirement from the foundation in 2015.