“The bet forced both of us to refine strongly held beliefs, and because our predictions were now public, our reputations were on the line,” Kelly later wrote. “This is what public wagers can do: sharpen logic, filter out the halfhearted. Sometimes they can even alter collective views and shape society.”

As Kelly notes, there’s a long history of these kinds of public wagers, particularly in science. In 01600, astronomer Johannes Kepler bet his rival Christian Longomontanus that he could derive the formula for the solar orbit of Mars in eight days. It took him five years. Kepler lost the bet, but his calculations ultimately helped bring about modern astronomy. In 01870, flat earther John Hampden made a 500 pound bet with naturalist Alfred Russel Wallace (who, it should be noted, conceived of the theory of evolution independent of Darwin) that he could prove the Earth was flat using the Bedford Level Experiment. Hampden lost the bet, insisted that Wallace cheated, and ultimately was imprisoned for threatening to kill Wallace. The myth of the flat earth was laid to rest, albeit temporarily.

The results from the Bedford Level Experiment confounded scientists for 30 years before it was realized that it is merely an optical refraction effect. Lateral Science

More recently, there’s the bet that biologist and environmentalist Paul Ehrlich made with economist Julian Simon in 01980. Ehrlich bet Simon $10,000 that the prices of five metals (copper, chromium, nickel, tin, and tungsten) would increase over a decade. The prices declined sharply, and Simon won the bet.

The Simon-Ehrlich wager.

The wager received a lot of publicity over the decade, and the result ultimately shaped societal thinking around limited resources. “Simon was a prolific skeptic of environmentalism,” Kelly wrote, “yet nothing that he ever wrote had as much impact on the course of culture as his wager with Ehrlich. That single, relatively small bet transformed the environmental movement by casting doubt on the notion of resource scarcity.” (Although, if the bet were repeated in subsequent decades, Ehrlich would have won, given the rise in commodity prices. On a long enough timescale, however, it’s one more blip in a multiple-centuries-long trend towards decreasing prices).

Kevin Kelly, Stewart Brand, and Long Now Executive Director Alexander Rose. Gary Wilson

Both Kelly and Long Now Foundation co-founder Stewart Brand were intrigued by the Simon-Ehrlich bet and the public accountability and long-term thinking it made possible. (Ehrlich was Brand’s teacher and mentor at Stanford, and his concerns around resource scarcity and overpopulation were ones Brand used to share). Brand formulated the idea that would become Long Bets in an email to the Long Now board in May 02001:

People bet people about things that will happen farther in the future than the horserace next weekend. Peter Schwartz almost bet Hunter Lovins today about when electric-drive autos will be the norm — -in 10–20 years or in 15–25 years. If Long Now offered a Longbets holding service, they could have bet, say $1,000, with the outcome to be decided in 02016. The money, the bet, and a fee could be placed with Long Now. The money draws interest in behalf of the eventual winner, minus a maintenance fee to Long Now. Long Now robots keep track of Peter and Hunter. As 2016 approaches the file wakes up and contacts them to begin negotiation toward resolution of the bet. If they don’t resolve, the amount is split 50–50. If they resolve, winner takes all. If only one of the two can be found, that person gets the winnings by default. If neither can be found, the money is held a while longer and then is absorbed into Long Now. I bet it will work.

It did. Brand founded Long Bets in 02002 with Kevin Kelly and a little seeding assistance from Amazon’s Jeff Bezos. The forum asks all predictors to put their name, a solid argument, and a financial pledge down in support of their statement about the future. Long Now, in turn, provides a long-term record where any prediction can be revisited, reviewed, and discussed at any time.

A Long Bet always starts with a prediction. All predictions should come with an argument in support, a financial pledge, and an end-date. The minimum term for a prediction is two years; there is no maximum term.

A prediction becomes a bet when a challenger comes forward with a counterargument. The predictor may then choose to make a bet with the challenger. The predictor and challenger will agree on a wager, and each will choose a charitable cause to receive the winnings.

When the end-date for the bet passes, The Long Now Foundation adjudicates the bet and donates the proceeds to the winner’s charity of choice.

The Long Bets site offers a public record of all predictions and bets. It highly encourages discussion about what we may learn, or what we have learned, from bets and their outcomes. This discussion feeds improvement of long-term thinking — the real pay-off.

The bets on Long Bets range from the serious, inculcating questions about what it means to be human, to the playful. The first Long Bet on record was between Mitchell Kapor, co-founder of The Electronic Frontier Foundation, and the futurist Ray Kurzweil, who popularized the idea of the technological singularity. Kapor bet Kurzweil $10,000 that by 02029, no computer — or “machine intelligence” — will have passed the Turing test (the test conceived in 01950 by mathematician Alan Turing that tests whether a machine is capable of human intelligence).

The first winner of a Long Bet was actor and Red Sox fanatic Ted Danson. In 02002, the late Time Editor Michael Elliott bet Danson $1,000 that the U.S. Men’s soccer team would win the World Cup before the Red Sox win the World Series. “The Red Sox have had such bad luck in the 20th century,” Danson argued, “I have to believe that in the new millennium it can only get better.” Danson would be vindicated a mere two years later.

The stakes of Long Bets typically ranged in the hundreds and thousands of dollars. Through 02007, the largest bet was the Kurzweil-Kapor Turing test bet. Then along came Warren Buffett.