The Simon–Ehrlich wager was a 1980 scientific wager between economist Julian Simon and biologist Paul Ehrlich, betting on a mutually agreed-on measure of natural-resource scarcity over the decade leading up to 1990. The widely followed contest originated in the pages of Social Science Quarterly, where Simon challenged Ehrlich to put his money where his mouth was. In response to Ehrlich's published claim that "If I were a gambler, I would take even money that England will not exist in the year 2000", Simon offered to take that bet, or, more realistically, "to stake US$10,000 ... on my belief that the cost of non-government-controlled raw materials (including grain and oil) will not rise in the long run". Simon challenged Ehrlich to choose any raw material he wanted and a date more than a year away, and he would wager on the inflation-adjusted prices decreasing as opposed to increasing. Ehrlich chose copper, chromium, nickel, tin, and tungsten. The bet was formalized on September 29, 1980, with September 29, 1990, as the payoff date. Ehrlich lost the bet, as all five commodities that were bet on declined in price from 1980 through 1990, the wager period.
Background In 1968 Ehrlich published The Population Bomb, which argued that mankind was facing a demographic catastrophe with the rate of population growth quickly outstripping growth in the supply of food and resources. Simon was highly skeptical of such claims, so he proposed a wager, telling Ehrlich to select any raw material he wanted and select "any date more than a year away," and Simon would bet that the commodity's price on that date would be lower than what it was at the time of the wager.
Terms of the wager Ehrlich and his colleagues picked five metals that they thought would undergo big price increases: chromium, copper, nickel, tin, and tungsten. Then, on paper, they bought $200 worth of each, for a total bet of $1,000, using the prices on September 29, 1980, as an index. They designated September 29, 1990, 10 years hence, as the payoff date. If the inflation-adjusted price of the basket rose above $1,000, Simon would pay Ehrlich the difference. If the prices fell, Ehrlich et al. would pay Simon.
Outcome Between 1980 and 1990 the world's population grew by more than 800 million, the largest increase in one decade in all of history. But by September 1990, the price of each of Ehrlich's selected metals had fallen. Chromium, which had sold for $3.90 a pound in 1980 (equivalent to $15.24 in 2025), was down to $3.70 in 1990 (equivalent to $9.12 in 2025). Tin, which was $8.72 a pound in 1980 (equivalent to $34.07 in 2025), was down to $3.88 a decade later (equivalent to $9.56 in 2025). As a result, in October 1990 Paul Ehrlich mailed Julian Simon a check for $576.07 (equivalent to $1,419.63 in 2025) to settle the wager in Simon's favor.
Analysis Julian Simon won because the price of three of the five metals went down in nominal terms and all five of the metals fell in price in inflation-adjusted terms, with both tin and tungsten falling by more than half. In his book Betrayal of Science and Reason, Ehrlich wrote that Simon asserted "that humanity would never run out of anything". Ehrlich added that he and fellow scientists viewed renewable resources as more important indicators of the state of planet Earth, but that he decided to go along with the bet anyway. Afterward, Simon offered to raise the wager to $20,000 and to use any resources at any time that Ehrlich preferred. Ehrlich countered with a challenge to bet that temperatures would increase in the future. The two were unable to reach an agreement on the terms of a second wager before Simon died. Some observers have argued that Ehrlich could have won if the bet had been for a different period, or if the start date had been different. Ehrlich wrote that the five metals in question had increased in price between the years 1950 and 1975. Asset manager Jeremy Grantham wrote that if the Simon-Ehrlich wager had been for a longer period (from 1980 to 2011), then Simon would have lost on four of the five metals. Economist Mark J. Perry noted that for an even longer period of time, from 1934 to 2013, the inflation-adjusted price of the Dow Jones-AIG Commodities Index showed "an overall significant downward trend" and concluded that Simon was "more right than lucky". Kiel et al. (2010) claimed that when considering all possible time periods from 1900 to 2008, Simon would have won the bet in only 38.4% of all cases, while Ehrlich would not only have won more often but also by a wide margin. They viewed the period from 1980 to 1990, during which the bet was active, as one of the 15 worst periods over the entire study period from 1900 to 2008. Contrary to popular public opinion, they posited, the conclusion of the bet is not that there is no such thing as a shortage of raw materials, but rather that when it comes to betting, it is better to have luck on your side than expertise.
The proposed second wager Understanding that Simon wanted to bet again, Ehrlich and climatologist Stephen Schneider counter-offered, challenging Simon to bet on 15 current trends, betting $1,000 that each will get worse (as in the previous wager) over a ten-year future period. The bets were:
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