National debates over environmental issues are sometimes derailed by two kinds of extremists: eco-doomsayers and techno-optimists. The two positions are best captured in the most dramatic bet in social science. It is useful to recall the tale, recently cataloged by Yale University historian Paul Sabin, because the legacy of the bet is with us today, above all in the domain of climate change.
Paul Ehrlich is a Stanford University biologist whose lifelong concern has been overpopulation. In the 1960s and 1970s, he issued dire warnings, most prominently in his 1968 best-seller, "The Population Bomb." Ehrlich argued that population growth would place increasing strains on the planet's natural resources, creating forms of scarcity that would produce widespread human suffering. Notwithstanding his personal ebullience, Ehrlich warned of "famines of unbelievable proportions" occurring by 1975 and of "hundreds of millions of people" starving to death in the 1970s and 1980s.
Ehrlich's great adversary was Julian Simon, an economist at the University of Illinois. Shy and awkward, Simon suffered from depression for more than a decade. But with respect to humanity's future, he was an optimist. Simon believed that because of free markets and technological ingenuity, population growth need not entail scarcity. Simon thought Ehrlich was essentially a fraud. He bristled at the ecologist's growing fame.