The Bet: Paul Ehrlich, Julian Simon, and Our Gamble over Earth's Future

"The Bet" gave me a new framework for interpreting science/policy debates: Neo-Malthusians vs. Cornucopians. Once you see it, you can't stop seeing it everywhere you look. Sabin elegantly traces the intellectual lineage of this debate through the lens of the Ehrlich/Simon wager.

The Bet: Paul Ehrlich, Julian Simon, and Our Gamble over Earth's Future

"The Bet" gave me a new framework for interpreting science/policy debates: Neo-Malthusians vs. Cornucopians. Once you see it, you can't stop seeing it everywhere you look. Sabin elegantly traces the intellectual lineage of this debate through the lens of the Ehrlich/Simon wager and does an excellent job of showing how their academic arguments influenced specific policymakers.

In one corner, we have Paul Ehrlich (of "The Population Bomb" notoriety) as our resident neo-malthusian. A Stanford population ecologist, he very passionately and very publicly proclaimed that hundreds of millions of people were going to starve to death in the 80's and 90's. As Sabin says, "Ehrlich embraced environmentalism as a secular religion."

In the other, we have the all-but-forgotten Julian Simon. A conservative economist of the Chicago school, he serves as our cornucopian by arguing that markets will allocate scarce resources and stimulate innovation to solve any population pressures.

After sniping at each other in academic papers for years, Simon challenged Ehrlich to put his money where his mouth was. Ehrlich thought resources were getting scarcer? Great - he should choose any 5 resources (he chose copper, chromium, nickel, tin, and tungsten) and in a decade, they'd see if the prices had gone up (reflecting scarcity) or down (reflecting plenty). They formalized the bet in 1980, and by 1990, every single one of the metals had gone down in (inflation-adjusted) price!

Sabin fleshes out the story with lots of historical details and sketches of the personalities involved. His treatment is even-handed and he points out issues with both Ehrlich's and Simon's approach. Sabin humanizes both of the opponents so that we can understand where they are coming from. Indeed, one of the key realizations is that a big part of the difference in perspectives was driven by values rather than by evidence. While Simon "placed human welfare at the center of his moral universe", Ehrlich thought that "humanity could not serve as the measure of all things."

Simon's victory would likely disturb many of today's environmentalists, doubly so because of his affiliation with conservative thinktanks like the Heritage Foundation and the Cato Institute (originally the Charles Koch Foundation). Sabin explores the roots of Republican anti-environmental sentiment - after all, this was the party of Theodore Roosevelt and the national parks! He does an excellent job of tracing the policy debate and identifying key players.

Many of those players are still on the scene today. Yale professors Dean Speth and William Nordhaus make appearances in the book, as do Anne Gorsuch (head of EPA, mother of now Supreme Court Justice Neil) and John Holdren (Ehrlich BFF and Obama's science advisor). Carl Sagan (ironically, author of "The Demon-Haunted World: Science as a Candle in the Dark") gets dragged a bit for his collaboration with Ehrlich on the ill-advised "nuclear winter" schtick. And everyone's favorite inconvenient politician Al Gore gets absolutely rocked by a frustrated Simon:

“After 25 years of the doomsayers being proven entirely wrong, their credibility and influence waxes ever greater.”

This was a tough book to swallow, although it crystalized many of my thoughts from other books in my 2017 reading theme on the "Integrity of Western Science". After "Higher Superstition", I was primed to recognize Ehrlich's attempt to turn environmentalism into a "secular religion" and his constant push for revolutionary change as archetypal of postmodern academic pseudo-science. Ehrlich gets explicitly called out in "Warnings: Finding Cassandras to Stop Catastrophes" for venturing outside his area of expertise (which, remember, was butterflies). Typical of neo-malthusians, he relied on oversimplified models and didn't account for human flexibility or the adaptability of markets. Now the trillion dollar question is... do these lessons apply to climate change as well?

My highlights below.


When I joined the history faculty at Yale University in 2008, I wanted to keep thinking about these issues, particularly our society’s inability to agree on what to do about climate change and other key problems. Writing about the rise of the environmental movement since the 1960s, and the backlash and debates it engendered, offered me a way to examine the striking divide that has emerged between liberals and conservatives on environmental questions.

Extreme claims by environmentalists, I argue, helped spark the backlash against the environmental movement in the United States and helped generate support for equally extreme positions taken by conservative opponents. Put another way, the political gulf that we see today on environmental issues has been mutually created.

I am grateful to Yale University for faculty research support, including funding from the Morse Fellowship in the Humanities, A. Whitney Griswold Fund, and Frederick W. Hilles Publication Fund.


The lanky man with short black hair and sideburns almost to his chin sat down next to late-night host Johnny Carson, for The Tonight Show, in early January 1970. Paul Ehrlich, a thirty-seven-year-old biology professor at Stanford, leaned forward in his seat, determined to alert his national television audience to the threat he saw imperiling humanity and Earth — the danger of overpopulation. Ehrlich had made his name two years earlier with a blockbuster jeremiad, The Population Bomb.

Ehrlich’s star continued to rise through the decade. Writing and speaking engagements poured in. He appeared on Carson’s show, one of the most coveted spots in television, at least twenty times. He also wrote a regular column for the Saturday Review and shared his fears about starvation and population growth with concerned readers in Playboy and Penthouse.

Rather than Ehrlich’s doomsday scenarios, Simon argued that more people meant more ideas, new technologies, and better solutions. Rather than sparking the world’s crises, population growth would help resolve them. People, as Simon titled his landmark 1981 tome, were The Ultimate Resource.

In 1980, Simon challenged Ehrlich in Social Science Quarterly to a contest that directly tested their competing visions of the future, one apocalyptic and fearful of human excess, the other optimistic and bullish about human progress. Ehrlich agreed to bet Simon that the cost of chromium, copper, nickel, tin, and tungsten would increase in the next decade.

Carter devoted precious political capital to changing American energy policy, considering it a national strategic priority. Ronald Reagan, by contrast, ran for office on the promise of restoring America’s greatness. Reagan insisted that resource limits weren’t real and shouldn’t constrain America’s future.

Ehrlich’s widely publicized fears about population growth revived the arguments of the Reverend Thomas Malthus, a political economist who famously declared in a 1798 treatise that the “power of population” exceeded “the power in the earth to produce subsistence for man.”

Early critics of Malthus, however, such as the English philosopher William Godwin, anticipated Julian Simon’s critique of Ehrlich, mocking Malthus’s conviction that humanity was doomed to misery. Malthus’s theory of relentless population growth, Godwin wrote in 1820, was just a “house of cards” that was “evidently founded upon nothing.” Godwin argued that population would grow much more slowly than Malthus predicted. He also believed that humanity had barely pressed against the vast resources of the planet. Earth, Godwin wrote, could support nine billion people with little improvement in technology. Other nineteenth-century critics of Malthus, such as Friedrich Engels, thought that agricultural productivity could be “increased ad infinitum by the application of capital, labour and science.” The “productive power at mankind’s disposal,” Engels declared, “is immeasurable.”

Ehrlich and other new prophets of overpopulation came to be called “neo-Malthusians” for their embrace of Malthus’s warnings about an inevitable gap between accelerating population growth and limited food supply.

Simon was influenced by the utilitarian philosophy of Jeremy Bentham, the British philosopher. Bentham proposed that the “measure of right and wrong” in society should be “the greatest happiness of the greatest number.”

Simon did not speak in the elementary terms of “pain and pleasure.” But he also placed human welfare at the center of his moral universe. Simon measured societal progress in terms of human life expectancy, prevalence of disease, available food and work, and per capita income. Paul Ehrlich rejected these simple calculations of societal success. Humanity, Ehrlich thought, could not serve as the measure of all things. Humans needed to accept their proper role in a larger balance of nature on earth.

CHAPTER ONE - Biologist to the Rescue

Ehrlich delivered The Population Bomb to an audience receptive to grim predictions about the future. That same year saw Robert F. Kennedy and Martin Luther King Jr. assassinated, riots in Washington, DC, Chicago, and Kansas City, and student rebellions in Paris and Mexico City.

To make sure The Population Bomb would reach the widest possible audience, Ehrlich paid his twelve-year-old daughter ten dollars to read the draft manuscript and flag any difficult passages.

He liked to have a good time with his friends, and although he enjoyed his studies, he later described his college years as majoring in “liquor and women.” With a loud voice and booming laugh, Ehrlich held forth with strong opinions on most any topic. The future of humanity provided a favored theme.

After a postdoctoral fellowship in Chicago, Paul and Anne Ehrlich moved with Lisa to Palo Alto in 1959, where Paul began a more than fifty-year career teaching in the biology department at Stanford University. His research in population biology would result in hundreds of scientific publications, including an influential 1965 paper, coauthored with Stanford colleague Peter Raven, that helped launch the study of co-evolution: the idea that animals and plants coevolve in a series of adaptive defenses and responses.

The furor over Rachel Carson’s 1962 book, Silent Spring, about the dangers of chemical pesticides, helped coalesce public concerns into a new political environmentalism. Ehrlich embraced environmentalism as a secular religion.

Ehrlich’s revulsion at India’s street life was common for Western visitors. Yet his instinct to blame sheer numbers of people, rather than their state of culture or governance, represented a shift in emphasis underway in Western thinking.

Starting in January 1968, around the time that Ehrlich was writing The Population Bomb, a group calling itself the “Campaign to Check the Population Explosion” started running full-page advertisements in the Washington Post and the New York Times. The imagery was apocalyptic.

President Johnson had refused to send American wheat to India in 1966 until that country adopted a vigorous family planning program. According to presidential adviser Joseph Califano, Johnson told him, “I’m not going to piss away foreign aid in nations where they refuse to deal with their own population problems.”

The massive scale of the eventual American relief effort is indisputable: over a two-year period, roughly one-quarter of annual US wheat production was sent to India.

These ideas did horrify many readers and listeners, such as the physicist Alvin Weinberg, director of the Oak Ridge National Laboratory. Weinberg denounced the “elitism” of wealthy and well-fed Americans declaring that the “Malthusian vise” was the only strategy to force people to have fewer babies. “When people starve, do we have any alternative but to try to give them food?” The idea that “misery imposed today... is necessary for the long-term good of man,” Weinberg wrote, “is scientific arrogance at its most outrageous.”

To their credit, biologists like Ehrlich, Remington, and Odum took aim at the growing sense of human control and power over nature that led to extravagant technological schemes, such as a late 1950s Project Chariot proposal to use nuclear explosions to create a deep-water port in Alaska. Yet, as Julian Simon would later argue, the biologists also showed little understanding for how people differ from butterflies and how economic systems could work to manage scarcity, drive investment and innovation, and avert shortages.

Holdren eventually joined the faculty at the University of California, Berkeley, where he cofounded the Energy and Resources Group, an interdisciplinary graduate program that he helped lead for more than twenty years. He continued to draw on his physics background to remain active on issues of nuclear arms control. Holdren played a key leadership role in the Pugwash Conferences on Science and World Affairs. In 1995, he gave the acceptance speech when that organization won the Nobel Peace Prize for its work on arms reduction and peace. Holdren, who also taught at Harvard University’s John F. Kennedy School of Government, would go on to become director of the White House Office of Science and Technology Policy under President Barack Obama.

After moving to Yale in 1968 as an assistant professor of physics, Harte joined with other young faculty to oppose the war and protest the militarization of scientific research. On March 4, 1969, Harte, along with fellow physicist Robert Socolow, helped to shut down science classes at Yale for a day of reflection about the war and scientific connections with the military.

Within a few years, Harte had started teaching an environmental problem-solving course in the Energy and Resources Group at Berkeley with John Holdren. Harte remained at Berkeley for the rest of his academic career.

His own view of a sustainable human population was radically small, expressed variously as approximately 17 percent (around 600 million) or, more commonly, 40 percent (1.5 billion) of the 1970 population of 3.7 billion people worldwide.

Ehrlich, the Yale biologist Charles Remington, and Richard Bowers, a Connecticut lawyer and conservationist, dreamed up Zero Population Growth after a game of squash in New Haven. Prominent biologists such as Garrett Hardin, Harvard’s Edward O. Wilson, and George Woodwell from the Brookhaven National Laboratory joined the organization’s board of directors.

Anne Ehrlich wrote to a colleague in 1969, “An amazing number of women have another baby because they have nothing else to do.”

Ehrlich rejected the idea that parents had an “inalienable right” to reproduce and said that perhaps an across-the-world limit of two children per family would be the most equitable approach.

In July 1969, just a year after Ehrlich published The Population Bomb, Nixon gave a speech calling global population growth a “world problem which no country can ignore.” He was the first American president to give population such prominent attention, a sign that Ehrlich’s public campaign was bearing fruit.

The Commission on Population Growth and the American Future, which started its work in 1970, would be headed by John D. Rockefeller III, a leading financial backer of Planned Parenthood, the Population Council, and other population organizations, as well as the grandson of the founder of Standard Oil.

In signing the National Environmental Policy Act on January 1, 1970, his first official act of a new decade, Nixon declared himself convinced that the “1970’s absolutely must be the years when America pays its debt to the past by reclaiming the purity of its air, its waters, and our living environment. It is literally now or never.”

In April 1970, more than twenty million Americans took to the streets to call for environmental action in the first Earth Day. Paul Ehrlich served on the small steering committee of only eight people for the national Earth Day organization.

Three months after Earth Day, Nixon pushed through a restructuring of the federal government’s anti-pollution programs to create a new, unified Environmental Protection Agency (EPA).

The new laws and the court rulings profoundly altered the federal government’s relationship to the environment and, therefore, the economy. It was a stunning and quick victory for the environmental movement, and the most profound and sudden shift in the relations between businesses and government since the end of World War II.

Ehrlich, who opposed the Vietnam War, also considered Nixon “one of the first major eco-criminals” for what Ehrlich considered an “ecocidal” attack on the people and environment of Vietnam.

Nixon increasingly focused on the high economic costs of environmental policy. He worried that the new environmental laws impeded economic growth, and he publicly warned against “ecological perfection at the cost of bankruptcy.” Privately, Nixon complained, “Some people want to go back in time when men lived primitively.”

When the police came to investigate, they found the Ehrlich’s house in disarray, with piles of papers and books in apparent chaos. The place had been ransacked, they thought. It turned out, however, in what would become a family joke, that this was just the way Paul and Anne lived.

Others questioned whether Ehrlich’s provocative style served him well, and criticized his apocalyptic rhetoric. As Eugene Odum, a leading ecologist, wrote to Ehrlich in 1970, “while some of us like yourself must remain ‘highly visible,’ we have also got to encourage many other ecologists to back up this visibility with what we might call real credibility.” In a tough review of Paul and Anne Ehrlich’s 1970 Population, Resources, Environment: Issues in Human Ecology, Roger Revelle, a leading oceanographer and the director of Harvard’s Center for Population Studies, called Ehrlich the “New High Priest of Ecocatastrophe.” The “emotional and quasi-religious force” of Ehrlich’s writing, Revelle wrote, was not likely to “lead to the hard thinking and effective action which the overwhelming issues so urgently demand.”

The theological association was not too far-fetched. In late 1968, just after The Population Bomb was published, Ehrlich delivered Sunday sermons in San Francisco’s Grace Cathedral and at Stanford’s Memorial Church.

John Lear, an editor at Saturday Review, for whom Ehrlich and Holdren wrote a regular column in 1970 and 1971, reported receiving telephone calls from leading scientists, as well as former Ehrlich students, to criticize Ehrlich’s essays.

As he wrote in a 1970 letter to William Draper, head of the Population Crisis Committee, “I am busily writing outrageous things in a continuing attempt to change the unchangeable.”

“The thing I would trust Ehrlich with is butterflies,” commented Philip Hauser, a demographer at the University of Chicago.

John Holdren’s inspiration, Harrison Brown, had worried about the “genetic soundness” of the human species. Frederick Osborn, a cousin of the Fairfield Osborn who wrote Our Plundered Planet, helped found both the American Eugenics Society in 1926 and the Population Council in 1952.

Environmentalism has never had a Martin Luther King Jr. figure to set and hold a moral compass for the movement and the nation. Ehrlich’s deep continuing commitment to his scientific research and teaching provided him with a rhetorical platform as a public intellectual but also limited his role.

CHAPTER TWO - Dreams and Fears of Growth

Simon’s talk, “Science Does Not Show There Is Over-Population,” laid out the themes he would pursue over the next few decades. “I view the population explosion not as a disaster, but as a triumph for mankind,” Simon boldly declared. “Whether population growth is too fast or too slow is a value judgment, not a scientific one.”

He also bore a grudge: two weeks later, at a faculty party, Simon accosted Silverman and threw a drink in his face. Scuffling ensued. It was an awkward, even violent, start to Simon’s public life.

Even as biologists like Paul Ehrlich highlighted intractable natural and physical limits to human activity, mainstream economists questioned the distinctive importance of natural resources. They instead emphasized human capital, technology, and innovation. Nature was just another factor in economic systems, they argued. Markets would successfully manage the depletion of resources by developing substitutes, moderating demand, and stimulating production.

In his polemical style, as well as his dedication to scholarship and to rational argument, Julian Simon greatly resembled Paul Ehrlich. This was no coincidence, since they came from similar Jewish communities in New Jersey.

Even as he disdained the elite, however, Julian Simon craved the external validation and opportunities for advancement that elite institutions offered. In 1949, he headed off to Harvard College on a navy ROTC scholarship. Along with Ehrlich, who enrolled at the University of Pennsylvania that same year, Simon was part of a generation of Jewish students who increasingly populated America’s top colleges and universities after World War II.

After graduating from Harvard in 1953 with a degree in experimental psychology, Simon spent three years as a unit officer on a naval destroyer and as an officer attached to the marines at Camp Lejeune in North Carolina.

When Simon arrived at the University of Chicago, economists such as Milton Friedman and Friedrich A. Hayek had started to challenge the New Deal economic orthodoxy.

Although Simon never studied with them directly, he considered Friedman and Hayek kindred spirits. “You can’t choose your relatives,” Simon later wrote. “But one can imagine.” His dream family consisted of a roster of famous theorists, some of them notable conservatives: “William James as my father, Hayek as my uncle, Milton Friedman as my older brother, Theodore Schultz as my thesis adviser, and David Hume as my idol.”

His attraction to James probably lay in the philosopher’s theory of pragmatism and its emphasis on “scientific loyalty to facts.”

While at Chicago, Simon met and married a graduate student in sociology, Rita James. Rita had been a leftist activist as a teenager, part of a socialist youth group in New York City. But she had left that behind. She also now found Chicago’s free-market approach liberating and exhilarating. Ayn Rand’s novels emphasizing individual rights and laissez-faire capitalism inspired Rita, as did Hayek’s Road to Serfdom.

Although family life in Urbana had its idyllic aspects, Julian Simon’s move into academia coincided with a dark turn in his personal life. He slipped into a depression that plagued him for about thirteen years.

Simon particularly found refuge in his work during these long years. Successfully completing academic writing projects provided a few bursts of pleasure outside family life. But his commitment to work also may have prolonged his depression. Simon refused medication to treat his illness because he feared that the side effects of the drugs would impair his clarity of thought.

Rita Simon thrived in the sociology department at the University of Illinois, becoming its first female chair in 1968. She continued to chair the department until 1983, leaving the position only for breaks during family sabbatical trips to Israel. Simon would serve a term as editor of the leading academic journal the American Sociological Review in 1978. Julian and Rita had a remarkably equitable marriage partnership, both pursuing demanding full-time academic careers. Julian had his limits as a pioneer in gender equity, however, in part due to his social awkwardness and ongoing depression; when Rita agreed to chair the sociology department, Julian insisted that Rita make clear that she didn’t have a “wife” and that they would not entertain at the house.

Simon’s early exhortations for action to lower birthrates, however, soon gave way to equivocation about the dangers of a growing population. His studies of birth control marketing and fertility drew him to probe the dynamics of family size. Changes in income and education influenced fertility quite differently depending on a family’s previous wealth and education. Additional income encouraged more educated women to have children. By contrast, greater income discouraged less educated women from having more kids. Additional education also had a differential impact. More schooling discouraged less educated women from having children far more than women who already were relatively highly educated. In another twist, smaller families often used additional income to have more children, while large families usually did not. In other words, fertility did not operate according to a single formula. No one strategy, it seemed, would successfully moderate or control fertility.

Simon later attributed his changed view to comparative data gathered by the economists Simon Kuznets and Richard Easterlin on the relation between national economic growth and population. The historical data, Kuznets and Easterlin argued in 1967 essays, did not show that population growth had undermined economic growth. “More population means more creators and producers,” Kuznets noted.

Contrary to Thomas Malthus, who believed that agricultural methods set limits for population, Boserup argued the opposite: population size and density determined what kind of agriculture would be practiced and would be economically efficient.

Arriving early, Simon visited the Iwo Jima memorial nearby. As he contemplated the memorial to the fallen soldiers, Simon recalled a famous eulogy given at Iwo Jima by the Jewish chaplain Roland Gittelsohn, who had bemoaned the loss of potential human talent and promise. Simon later wrote, “And then I thought, Have I gone crazy? What business do I have trying to help arrange it that fewer human beings will be born, each one of whom might be a Mozart or a Michelangelo or an Einstein — or simply a joy to his or her family and community and a person who will enjoy life?

Simon embraced a utilitarian view, arguing that “the larger the number of people who are alive, the greater the welfare.” He called this a “biblical-Utilitarian welfare function” because of the Bible’s injunction to be fruitful and multiply.

In 1972, an international group of industrialists, scientists, and political leaders called the Club of Rome published The Limits to Growth: A Report for the Club of Rome’s Project on the Predicament of Mankind.

The book’s sponsors at the Club of Rome called for a “Copernican revolution of the mind,” declaring that “only a conviction that there is no other avenue to survival can liberate the moral, intellectual and creative forces required” to achieve a state of global equilibrium.

Ehrlich himself wrote a blurb for the book, calling it “a great service”; he challenged readers unsettled by it to work “for changes in the real world.”

New York Times columnist Anthony Lewis called The Limits to Growth “one of the most important documents of our age.”

In an influential essay in Foreign Affairs the following spring, James Akins, a top State Department oil adviser and later ambassador to Saudi Arabia, chose a different metaphor for an incipient oil crisis, declaring, “This time the wolf is here.” The wolf arrived on October 16, 1973.

During the five-month-long embargo, oil prices quadrupled from around three dollars per barrel to more than twelve dollars. The sudden supply cut and price surge inflamed fears about resource scarcity and, for many contemporary observers, seemingly confirmed the thesis of The Limits to Growth. “Running Out of Everything,” declared a Newsweek cover that November, depicting a fearful Uncle Sam gazing into an empty horn of plenty.

Other critics questioned the accuracy of the Limits to Growth model, disputing the book’s feedback loops among population growth, resources, death rates, and pollution. They particularly ridiculed the seductiveness of the new computer models. Max Lerner, writing in the Los Angeles Times, mocked, “You can see the curves rising, falling, galloping, dancing, converging, interlocking, but always moving toward doom.” In a bit of lyrical criticism, he continued, “Ashes to ashes / And dust to dust. / If the bomb doesn’t get you / The exponential curves must.” More harshly, the New York Times Book Review called the book “little more than polemical fiction.” The Limits to Growth, the Times reviewers declared, was not so much a “rediscovery of the laws of nature but... [a rediscovery] of the oldest maxim of computer science: Garbage In, Garbage Out.” The book’s computer model, they said, “takes arbitrary assumptions, shakes them up and comes out with arbitrary conclusions that have the ring of science.”

The economists Harold Barnett and Chandler Morse, who dismissed fears of limits and resource exhaustion in their 1963 book, Scarcity and Growth: The Economics of Natural Resource Availability, particularly influenced Julian Simon. Barnett and Morse argued that the economics of natural resources had changed with humankind’s “increased knowledge of the physical universe, changes which have built technological advance into the social processes of the modern world.” “The notion of an absolute limit to natural resource availability,” they wrote, “is untenable when the definition of resources changes drastically and unpredictably over time.”

Yale economist William Nordhaus dismissed the model and calculations of Jay Forrester’s World Dynamics, the 1971 book that fathered The Limits to Growth, as “measurement without data.” Nordhaus said that Forrester allowed for “no technological progress, no new discovery of resources, no way of inventing substitute materials, no price system to induce the system to substitute plentiful resources for scarce resources.” The model, in other words, did not match how human economies actually work. In the real economy, Nordhaus explained, abundant resources and new technologies responded to scarcity: “iron, aluminum, and communication satellites replace copper; chlorine replaces iodine; the xerography process replaces use of tin and lead in printing.” This substitution would continue, Nordhaus said, unless the future turned out to be “very different from the past.” Nordhaus complained that the Forrester model — and, by extension, The Limits to Growth — treated human society as a “population of insentient beings, unwilling and unable to check reproductive urges; unable to invent computers or birth control devices or synthetic materials; without a price system to help ration scarce goods or motivate the discovery of new ones.” Human beings, Nordhaus’s analysis suggested, had more options than Ehrlich’s butterflies.

Although he acknowledged the importance of population growth, environmental degradation, and resource exhaustion, Solow emphasized that these issues were subject to standard economic analysis and did not present ominous and unmanageable threats.

But rather than provide an important warning that might lead to sensible action, Solow concluded, the Limits to Growth models “divert attention from remedial public policy.” He asked, “Who could pay attention to a humdrum affair like legislation to tax sulfur emissions when the date of the Apocalypse has just been announced by a computer?”

Simon’s general perspective on population and resource scarcity instead reflected increasingly common ideas among economists such as Solow and Nordhaus about the adaptability of market economies.

Where ecologists viewed scarce resources as a fundamental constraint that either forced dramatic change or provoked crisis, economists saw scarcity and abundance as constantly shifting, dynamic variables. In an ecosystem, scientists argued, resource abundance prompted excessive growth, followed by collapse when scarcity returned. In a marketplace, economists said, abundance also yielded growth; scarcity, however, did not lead to crisis. Rather, scarcity created challenges that spurred the economy in new directions.

CHAPTER THREE - Listening to Cassandra

“Resource experts throughout history have become a chorus of Cassandras,” complained Senator Gaylord Nelson of Wisconsin, a leading environmentalist in Congress who had proposed the first Earth Day celebrations and teach-ins. Nelson referred to the Greek prophetess whose warnings about future catastrophes, though accurate, were ignored. Like Cassandra, scientists like Ehrlich and Holdren possessed the ability to predict “worldwide catastrophe” from population growth and resource scarcity but faced the curse of not being believed. The entire world now risked the “dire consequences of Cassandra’s predicament,” Nelson warned. The enthusiastic embrace of Ehrlich and Holdren by leading politicians indicated how environmentalists were outgrowing the Cassandra role — their message, in fact, was widely heard and increasingly influential. Ehrlich and Holdren shared prophecies of scarcity and devastation at the Senate hearing. “A new era in the world” was coming, Ehrlich said, taking people from an “age of abundance to an age of scarcity.”

Speaking after Ehrlich, Holdren defended The Limits to Growth, The Population Bomb, and similar books. Critics of The Limits to Growth argued that market prices, technological innovation, and inexpensive energy could “somehow bail us out.” Holdren disagreed. He thought that economists like Robert Solow and William Nordhaus misunderstood the role of their own discipline. Economics, Holdren acknowledged, helped allocate scarce resources efficiently through prices. But prices and markets could not make “scarce resources less scarce.” Holdren thus returned again to the idea of fundamental ecological limits that economics could not overcome. Economists understood resources, labor, and capital as interchangeable factors in economic production, but Holdren insisted that ecosystems could not be maintained by artificial means. No “technological equivalent” existed for natural ecosystems. Humans could not run Earth like an “Apollo capsule,” he said, referring to the space program. He saw “unwarranted technological optimism” as the “most dangerous tendency” facing society. Holdren declared himself “firmly in the neo-Malthusian camp,” convinced that population growth would outstrip available resources.

The Ehrlichs urged a “relaxed lifestyle, good friends, and a happy sex life” over fame and profit.

The Kentucky poet Wendell Berry, in a widely circulated essay called “Think Little,” argued that war, racial oppression, and pollution all were interrelated — caused by the “mentality of greed and exploitation.”

Although the natural gas crisis resulted largely from a dysfunctional, regulated market, Carter thought that the gas shortages represented the future of energy scarcity that he had talked about during his campaign.

If Ecoscience’s arguments had a distinctive and characteristic weakness, it lay in the authors’ supreme confidence that they could calculate the absolute limits of human and environmental potential.

One of Ehrlich’s scientific colleagues at Stanford, the Nobel Prize–winning physicist William Shockley, spoke disparagingly of the intelligence of African Americans and called for eugenic policies to strengthen the genetic evolution of the human species. Ehrlich despised Shockley and his views on race, but he also saw that critics often linked his own campaign against population growth with the eugenic ideas of people like Shockley.

1977, the same year he published Ecoscience, Ehrlich also coauthored The Race Bomb: Skin Color, Prejudice, and Intelligence, with Stanford psychologist Shirley Feldman. Ehrlich and Feldman’s book attacked Shock-ley’s ideas about “race,” saying that the “race-IQ debate” was a “scientifically useless discussion.” “Since there are no biological races to begin with,” Ehrlich and Feldman wrote, “the question of the inferiority or superiority of a race is meaningless.” Yet they recognized the powerful impact of racial ideas, which were helping to “push civilization toward the brink of catastrophe.”

As one Zero Population Growth spokesperson wrote in the Washington Post in 1974, “At a time when we are having great difficulty providing jobs for our own native-born citizens, employment competition by immigrants is an increasingly serious problem.” In 1977, Zero Population Growth launched a national campaign to press for curbs on legal and illegal immigration. A fundraising appeal signed by Paul Ehrlich described illegal immigration as a “human tidal wave” that was “depressing our economy and costing American taxpayers an estimated $10 billion to $13 billion a year in lost earnings and taxes, in welfare benefits and public services.”

Rita and Julian also enjoyed a deep commitment to Israel and the “glory of Jerusalem.” They spent several sabbatical years living there with their children. During one sabbatical, Julian Simon regularly joined the security patrols in their Jerusalem neighborhood.

Back in the United States, Julian Simon’s professional life improved, and he gained new recognition and success. Simon had a significant personal triumph when his quirky proposal for an airline-bumping auction was adopted in 1978 by the federal agency that oversaw air travel.

By 1991, six hundred thousand people per year voluntarily accepted compensation in exchange for switching to a later flight. It was one of Simon’s more practical accomplishments and illustrated for him the power of markets to improve social welfare.

In 1980, Simon would launch a blistering attack on Ehrlich in both academic and popular forums. Ehrlich, however, had not yet noticed Simon as a particular threat; indeed, he never would acknowledge the unconventional economist as a worthy opponent.

The final summary chapter of Ecoscience contrasted two views of the future: “cornucopian” and “neo-Malthusian.” Ehrlich and his coauthors criticized “cornucopian” thinkers for presuming that cheap energy and technological innovation could generate widespread abundance and for underestimating how extensively proposed technologies would degrade the natural environment. Ehrlich argued that the loss of what he called “ecosystem services,” such as soil fertility or climatic balance, posed the “gravest threat to human well-being.”

After two years of delay, the White House finally released The Global 2000 Report to the President in July 1980. The Global 2000 Report ended up becoming a global phenomenon, selling 1.5 million copies in nine languages. Food and energy prices would more than double by 2000, the study predicted. Poverty and hunger would “haunt the globe,” according to news coverage of the report.

CHAPTER FOUR - The Triumph of Optimism

Simon and Ehrlich clashed in print directly for the first time in the summer of 1980. In the June issue of Science, Simon launched a blistering attack on environmental doomsayers. He opened the article by debunking a Newsweek and United Nations story that more than a hundred thousand West Africans had died of hunger caused by drought between 1968 and 1973. In fact, only a small fraction of that number had died as a result of the drought. Exaggerated statistics were an all-too-common tool of manipulation, Simon argued: bad news about population growth, resources, and the environment “published widely in the face of contradictory evidence.

In conclusion, Simon asked why “false statements of bad news” dominated public discussion. He blamed financial incentives for researchers who sought grant funding and the fact that “bad news sells books, newspapers, and magazines.” Simon also suggested a psychological explanation, arguing that people tended to compare the present and future with an “ideal state of affairs” rather than with the past.

And all of this had the proverbial effect of the boy who cried wolf. Rather than “harmless exaggeration,” apocalyptic predictions by Ehrlich and other environmentalists, Simon thought, resulted in a “lack of credibility for real threats” and a “loss of public trust.”

Simon also acknowledged that he simply differed from the scientists on the basic question of the “rights of nonhuman species to exist.” “In tradeoffs between human beings and the rest of nature,” Simon wrote, “my sympathies usually lie with people.”

“How often does a prophet have to be wrong before we no longer believe that he or she is a true prophet?” Simon goaded. He argued that Ehrlich had been wrong about the “demographic facts of the 1970s,” whereas Simon’s own predictions had been right. Ehrlich had said in 1969, for instance, “If I were a gambler, I would take even money that England will not exist in the year 2000.”

Ehrlich took the bait, accepting Simon’s “astonishing offer before other greedy people jump in.” Ehrlich consulted with his friends John Holdren and John Harte to choose the raw materials whose supply they thought would come under the greatest pressure. They chose five key metals. Each played a critical role in the modern economy. Chromium was a crucial element in stainless steel and valued as a corrosion-resistant coating. Copper had been used for thousands of years for its malleability and then later for its ability to conduct heat and electricity. Nickel helped make stainless steel and batteries and magnets. Tin yielded corrosion-resistant alloys. Tungsten’s heat-resistant characteristics found uses in lightbulbs, cathode-ray tubes, heating elements, and alloys.

For both sides, the real winnings would be bragging rights and the chance to prove that they were right about the future course of history. It was, as the Chronicle of Higher Education reported, “the scholarly wager of the decade.”

In retrospect, Reagan and the Republican Party’s extreme rhetorical turn against environmentalism in the early 1980s can be seen in part as a response to the equally extreme warnings about imminent doom emanating from Carter and environmentalists like Ehrlich.

Reagan derided Carter’s apparent pessimism about the American future. “They tell us we must learn to live with less, and teach our children that their lives will be less full and prosperous than ours have been… . I don’t believe that. And, I don’t believe you do either. That is why I am seeking the presidency. I cannot and will not stand by and see this great country destroy itself.”

“We used to have problems,” Reagan said dismissively in a 1971 speech to the American Petroleum Institute. “Today we have crises.” People like Paul Ehrlich were simply “anti-technology” and “anti-industry.” “The doomsday crowd,” Reagan said, “always seem to ignore the very real progress we have made.”

“Well, you know there was a fella named Malthus who thought we were going to run out of food,” Reagan declared in September 1980. “But Malthus didn’t know about fertilizers and pesticides.”

On the recommendation of the heads of the environmental organizations, Carter appointed James Gustave Speth, a cofounder of the Natural Resources Defense Council, to chair the Council on Environmental Quality.

“I am an environmentalist,” Reagan said during the campaign, but he thought that the Environmental Protection Agency tended to “insist on unreasonable and many times untried standards.”

Reagan also created a new cabinet-level task force on regulatory relief led by Vice President George H. W. Bush.

Just before joining Reagan’s cabinet, Watt served as the first president of the Mountain States Legal Foundation, a nonprofit legal center funded by Joseph Coors Sr. of the Coors Brewing Company, to strengthen private property rights and contest government regulation. Coors also had founded the conservative Heritage Foundation to provide a philosophical underpinning for the anti-environmental movement. From its inception, the Heritage Foundation urged followers to “strangle the environmental movement,” which Heritage named “the greatest single threat to the American economy.”

Reagan’s selection of Colorado state representative Anne Gorsuch to run the Environmental Protection Agency appalled environmentalists almost as much as Watt’s appointment. A former lawyer for the regional telephone company, she had been elected to the Colorado legislature in 1976, where she made her reputation as one of the “House Crazies” who sought a fundamental conservative overhaul of government. Known as the “Ice Queen” and the “Dragon Lady,” Gorsuch immediately started making enemies among the EPA’s career staff after her arrival at the agency. Critics — including Russell Train, the EPA’s second administrator under Nixon and Ford — warned that Gorsuch’s proposed personnel and budgetary cuts threatened to “destroy the agency as an effective organization.”

Environmental organizations became increasingly allied with the Democratic Party and with moderate Republicans, whose numbers were starting to shrink. The environmentalists flexed their political muscle effectively in their fights with Watt and Gorsuch. Both appointees had been driven from office by the end of 1983.

With political success, however, came the recognition of a new vulnerability. Professional national environmental organizations increasingly depended on doomsday warnings to raise money to fuel their growth. Watt played such an outsized role as a bogeyman for environmentalists that his departure nearly caused a financial crisis for the Sierra Club.

Ehrlich could not fathom the possibility that fundamentally different values or ideologies might yield different conclusions.

Ehrlich also served as lead author and chief organizer for an essay in Science on the “Long-Term Biological Consequences of Nuclear War.” Twenty other prominent scientists, including Carl Sagan and Stephen J. Gould, signed on as coauthors.

Ehrlich also coedited, along with Carl Sagan and two others, a 1984 report from the Cambridge conference, entitled The Cold and the Dark: The World After Nuclear War.

While Ehrlich darkly contemplated the end of civilization, Julian Simon encountered a newly enthusiastic audience in Washington, where the Reagan administration brought free market advocates and critics of environmental regulation into power. Simon’s controversial essay in Science in 1980 changed everything for him, and he relished the attention that followed. “I have hit the jackpot,” he wrote in notes to himself the following year.

Julian Simon completed the final touches on what he hoped would be his magnum opus, The Ultimate Resource. Published in 1981 by Princeton University Press and excerpted over three issues of the Atlantic Monthly, the book crystallized Simon’s thinking about the relation between population and resources issues in accessible prose. In Simon’s formulation, people were the “ultimate resource.” “Human resourcefulness and enterprise” could meet impending shortages and solve problems indefinitely. In fact, new solutions generally would leave society “better off than before the problem arose.”

Adam Smith and Friedrich Engels, as well as later writers such as Jules Verne and H. G. Wells, had “given full weight to man’s imagination and creative powers” to solve population and resource problems. More recent inspirations included Simon Kuznets’s national income and population research, Harold Barnett’s writings on resource scarcity, and Ester Boserup’s theories about agricultural innovation. Simon argued that food, land, natural resources, and energy were all becoming more abundant, not scarcer. How did he know? Rising prices and a rising ratio of price to income were the indicators of scarcity. Yet since the beginning of the Industrial Revolution, resource prices generally had fallen, particularly relative to income.

Drawing on a utilitarian perspective that aspires to the greatest good for the greatest number, Simon contended, in his own variant of the theory, that more people living rewarding lives maximized social welfare. “Because people continue to live, I believe that they value their lives. And those lives therefore have value in my scheme of things.”

On the public television show Firing Line, conservative commentator William F. Buckley declared that “Julian Simon may be the happiest thing that has happened to the planet since the discovery of the wheel.”

In the spring of 1983, Simon and coauthors in The Resourceful Earth presented their findings at the American Association for the Advancement of Science meeting in Detroit.

At a speech in Texas in 1983, Vice President George H. W. Bush embraced Julian Simon’s way of thinking about natural resources issues. Bush denounced The Global 2000 Report as a vision of stagnant economic growth and an “age of limits.”

Bush’s speechwriter, Joshua Gilder, wrote to thank Julian Simon for his “inspiration and research.” Gilder called himself a “great fan” of Simon’s work.

Julian, meanwhile, had received a grant from the Sloan Foundation to study the economic consequences of immigration, which paid half his salary for eighteen months. He became a senior fellow at the Heritage Foundation and also eventually landed a faculty appointment position teaching business administration at the University of Maryland.

The meeting brought Simon closer to Washington business conservatives such as Fred Smith at the Competitive Economy Foundation (who later founded the Competitive Enterprise Institute). Smith warned, “Conceding any legitimacy to a government data collection role is in my opinion extremely dangerous.” Rather than more regulation, Smith called for “free market environmentalism” led by private-sector entities through market mechanisms and private property rights.

In a 1985 essay in the Washington Post, for example, Simon contended that governments and development agencies continued to focus on overpopulation as the cause of international development problems in order to avoid talking about the more obvious cause of underdevelopment — dysfunctional economic and political systems.

Just as he had pushed for an auction for airline tickets, Simon suggested that the United States auction off rights to enter the country. Liberals denounced his idea, saying that it betrayed the values of the nation and the preferences given to refugees, relatives, and skilled workers. But Simon viewed immigration as a way to turbocharge the economy with new entrepreneurial citizens. His idea would later be adopted in modified form in the 1990 immigration act, which provided visas for immigrant investors.

Simon’s unorthodox position on immigration ultimately led to him shifting his affiliation from the Heritage Foundation to the Cato Institute, which was more committed to free market ideology.

After his years struggling to get attention, Simon marveled at Heritage’s ability to do “repeatable magic” in drawing attention to his work.

Following Ester Boserup’s arguments about agricultural innovation, the report pointed out that technological advances came about through scarcity, which stimulated “a search for economizing strategies.”

Environmental economist Herman Daly also criticized the report as trapped by the “mental straitjacket” of neoclassical economics. The report simply ignored the constraints of long-term carrying capacity, Daly said. Daly rejected the idea that capital could replace natural resources — a “notion that cannot withstand even a moment’s reflection.” Daly spoke favorably of the Chinese population policy, which rejected market solutions in favor of “stringent population controls.” Daly confessed his “astonishment” that a committee of the National Academy of Sciences would favor conservatives like Julian Simon and Herman Kahn over biologists such as Paul Ehrlich and Garrett Hardin.

“Stupidity in high places — including the lofty places here in this World Bank Building — has cost the lives of tens of millions or even hundreds of millions of human beings in the last decade or so, far more human lives than were lost in World War II.” Simon blamed “simple racism,” a “corrupt” relationship between researchers and policy-makers, and the desire to avoid divisive political and economic reforms for the continued embrace of population control. The “world’s problem,” Simon concluded, was “not too many people, but lack of political and economic freedom.”

CHAPTER FIVE - Polarizing Politics

One day in October 1990, Julian Simon picked up his mail at his house in suburban Chevy Chase, Maryland. In a small envelope sent from Palo Alto, California, Simon found a sheet of metal prices along with a check from Paul Ehrlich for $576.07. There was no note. Simon had prevailed in their bet, by every measure. Despite a record increase in the world population from 4.5 to 5.3 billion people, the prices of the five minerals — chromium, copper, nickel, tin, and tungsten — had fallen by an average of almost 50 percent.

In his 1990 telling of the bet in the New York Times Magazine, Tierney portrayed Ehrlich as a fraud, a MacArthur Fellowship–winning jet-setter whose predictions — about almost everything — were spectacularly wrong. Tierney located Ehrlich at the end of a trail of failed prophecy that started with Thomas Malthus and continued through the nineteenth-century British economist William Stanley Jevons to the twentieth-century American natural scientists Fairfield Osborn and William Vogt.

The Ehrlich-Simon bet confirmed “cornucopian claims that the supply of resources is becoming more abundant, not more scarce,” wrote libertarian economist Ron Bailey in his 1993 book Eco-Scam: The False Prophets of Ecological Apocalypse. Bailey argued elsewhere that the problem with the environmental movement was a “failure of theory” — an overreliance on flawed models that yielded exaggerated predictions of doom.

Macroeconomic cycles, far more than population growth, had governed the rise and fall of commodity prices over the course of the decade.

New sources of supply, product substitution, and, above all, the breaking of the tin cartel had a far greater impact than population growth on tin prices, ultimately driving them down almost 75 percent.

As most economists knew intuitively, and as Ehrlich learned painfully, volatile commodity prices served as a poor proxy for the impact of population growth, certainly over the course of just a decade. Subject to so many competing forces, commodity prices frequently cycle from boom to bust and from scarcity to overabundance. Ehrlich’s bet had been foolhardy — as even he later admitted. The bet also suggested that Ehrlich and his colleagues only tenuously understood economics and commodity markets.

William K. Reilly, the new administrator of the Environmental Protection Agency, contrasted strikingly with James Watt and Anne Gorsuch, the western firebrands Reagan had embraced in 1981. After growing up largely in the East, Reilly went to college at Yale and got a law degree from Harvard. Reilly served briefly as a military intelligence officer in Europe in the late 1960s and then returned to the United States to go back to school, completing a master’s degree in urban planning at Columbia.

After his early stint in government, Reilly served as president of two centrist environmental organizations, the Conservation Foundation and the World Wildlife Fund, between 1973 and 1989.

At the same time, other Bush appointees leaned in the opposite direction, including John Sununu, Bush’s chief of staff and the former governor of New Hampshire. Sununu stressed the economic costs of regulation. He had a doctorate from MIT in mechanical engineering, and he viewed climate models skeptically, questioning whether costly proposals to cut carbon dioxide emissions made sense or were being driven by “emotions.”

The first report, published in 1990 with contributions from hundreds of scientists around the world, emphasized uncertain ecological relations and financial costs, and called for extensive additional research to ascertain the likely impact of climate change on ecosystems and human societies. The IPCC’s discussion of scientific uncertainty and risk partly reflected a maturing of the environmental field and a more measured approach than Ehrlich’s strident public linking of science, policy, and advocacy.

As the 1992 election approached, Bush mocked the environmental beliefs of vice presidential candidate Al Gore, calling Gore “Ozone Man.” Bush declared that Gore was “so far out in the environmental extreme we’ll be up to our necks in owls and outta work for every American. He is way out, far out, man.”

In the early 1990s, leading authors from the 1970s updated their earlier reports with resounding affirmations of their earlier predictions. In The Population Explosion, Paul and Anne Ehrlich revisited the conclusions of The Population Bomb and argued that the preceding two decades had proven them right. “Then the fuse was burning; now the population bomb has detonated.” They asked plaintively, “Why isn’t everyone as scared as we are?”

For Ehrlich and many like him, entrenched positions held, now stated all the more emphatically. In Beyond the Limits (1992), Dennis Meadows and his coauthors of The Limits to Growth affirmed their original thesis, declaring that “without significant reductions in material and energy flows, there will be in the coming decades an uncontrolled decline in per capita food output, energy use, and industrial production.”

Beyond the Limits, Yale economist William Nordhaus wrote, was just “Lethal Model 2,” a retread of the 1972 Limits to Growth. The new report served up the “same cast, plot, lines, and computerized scenery.” Nordhaus warned that the book’s prescription risked “sav[ing] the planet at the expense of its inhabitants.”

But Nordhaus saw many ways around the pessimistic scenarios. For two centuries, he wrote, “technology has been the clear victor in the race with depletion and diminishing returns.”

No other “prominent doomsayer” had been willing to bet him, Simon claimed. So he called out the “chief ‘official’ doomsayer, Vice President Al Gore.” Gore’s book about environmental problems, Earth in the Balance, was “as ignorant and wrongheaded a collection of clichés as anything ever published on the subject.” Simon admitted that his own bluster and challenges made for “unpleasant, rude talk.” But proposing a bet was the “last refuge of the frustrated.” He complained, “After 25 years of the doomsayers being proven entirely wrong, their credibility and influence waxes ever greater.”

Simon refused Ehrlich and Schneider’s terms. Their proposed indicators affected human welfare only indirectly, Simon argued. Simon instead suggested indicators that directly measured human health and economic well-being, things like life expectancy, leisure time, purchasing power, and commodity prices. Rather than bet on change in a physical entity such as the ozone layer, Simon suggested measuring “the trend in skin cancer death.” The physical world, Simon argued, could change around us, but progress of human society would continue, bolstered by new technologies, adaptation, and markets.

Rather than find common ground, or even common terms for a second wager and debate, Ehrlich and Simon denounced each other in increasingly ad hominem and abusive language during the 1990s.

“I already know I’m a jerk,” Simon countered. “But I’ve been right every time. I’ll be right this time.”

Reviewing Al Gore’s Earth in the Balance in 1992, for example, Simon wrote that “truth” was under siege, “rather than our very durable planet.” Gore’s book was just an “ignorant... collection of cliches.” Simon considered Gore’s ignorance “willful rather than naive.” Gore simply chose to “ignore the scientific literature.”

Although many millions of people have died of hunger-related causes since the late 1960s, the connection between famine and population size is tenuous. Historians of famine emphasize instead dysfunctional markets, oppressive states, and warfare as the primary causes of famine-related deaths.

Attacks by Julian Simon and other conservative critics did not diminish Paul Ehrlich’s professional stature, particularly among scientists and liberal philanthropists. To the contrary, the 1990s provided many opportunities for scientists and environmentalists to celebrate the Ehrlichs’ work. Starting in the 1980s, Paul Ehrlich had received distinguished achievement and service awards from the Sierra Club, World Wildlife Fund International, and the American Association for the Advancement of Science. During the 1990s, as Paul and Anne entered their sixties, Paul received many of the top awards available to him, sometimes jointly with Anne. The Crafoord Prize from the Royal Swedish Academy of Sciences and a MacArthur Fellowship in 1990, the Volvo Environment Prize in 1993, the UN Environment Programme Sasakawa Environment Prize in 1994, a Heinz Award for the Environment in 1995, the Heineken and Tyler Prizes in 1998, and Blue Planet Prize in 1999. All told, the Ehrlichs received more than a million dollars in prize money during the 1990s, a significant portion of which they plowed into the Population Biology Gift Fund that supported their work at Stanford.

Simon was not invited to join any boards of economics journals, nor was he invited to give talks at prominent economic meetings. He complained that he did not get the credit that he deserved for innovations in statistical resampling methods and techniques for “bootstrap economics.”

John Tierney, the New York Times journalist and friend of Simon, commemorated Simon’s passing, mocking the MacArthur Foundation for giving “genius grants” to Ehrlich and John Holdren, the losers in the bet, while ignoring Simon.

Stephen Moore, from the Club for Growth, received the first Julian Simon Memorial Award. In subsequent years, the award went to Robert L. Bradley, a free market energy scholar, and Bjørn Lomborg, a Danish environmental contrarian.

Simon’s sharp critique of the environmental doomsday narratives intrigued Lomborg, a statistics professor in Denmark who had a long-standing interest in environmental problems. According to his narrative of self-realization, Lomborg enlisted his students to prove that Julian Simon was just a right-wing American propagandist. To their surprise, he said, they found merit in Simon’s arguments. “The world is not without problems,” Lomborg concluded in The Skeptical Environmentalist, “but on almost all accounts, things are getting better.”

In a provocatively titled New York Times essay — “The Environmentalists Are Wrong” — Lomborg argued that for the same price of rapidly cutting carbon emissions, “we could provide every person in the world with clean water,” thereby saving two million lives each year and preventing five hundred million incidents of severe disease. He urged substantial investment in new low-carbon energy technologies instead of mandatory emission cuts.

Edward O. Wilson called The Skeptical Environmentalist a “scam” characterized by “willful ignorance, selective quotations, disregard for... genuine experts, and destructive campaigning.”

Some scholarly commentators noted that Lomborg and his critics proceeded from different sets of values, and that scientific data alone could not provide the answers to fundamentally non-scientific policy questions. In the journal Environmental Science and Policy, several scholars argued that the controversy over The Skeptical Environmentalist showed how science was increasingly being used as a “trump card” in “disputes about values.”

“Many environmental claims are not so much about life’s quantities as its qualities. They are about aesthetic and moral choices. They are about equity and ethics.”

CHAPTER SIX - Betting the Future of the Planet

Each had important insights to offer about science, economics, and society. But neither presented a vision that can stand alone. The history of Ehrlich and Simon’s conflict instead reveals the limitations of their incompatible viewpoints. Their bitter clash also shows how intelligent people are drawn to vilify their opponents and to reduce the issues that they care about to stark and divisive terms.

Paul Ehrlich’s contribution—and that of environmental scientists as a whole after World War II — lay in the ability to reveal the deep connections between humans and nature and to show how the planet was changing.

If scientists had not raised the alarm about declining stratospheric ozone, nations never would have passed the 1987 Montreal Protocol, which phased out chemicals that damage Earth’s protective cover against intense solar radiation.

Sometimes rhetorical sparring partners hone each other’s arguments so that they are sharper and better. The opposite happened with Paul Ehrlich and Julian Simon. Despite their respective strengths, both Ehrlich and Simon got carried away in their battle.

Most fundamentally, human history over the past forty years has not conformed to Paul Ehrlich’s predictions.

One problem with Ehrlich’s style of argument is that environmental pessimism often far exceeds reasonable predictions for how markets function and scarcity develops.

Major solar power companies in the United States went bankrupt, while, at the same time, the green jobs economic programs did relatively little to stimulate job creation and spur short-term economic recovery. Aggressive subsidies by the Chinese government, of course, complicated this story by also helping competing Chinese manufacturers undercut American suppliers.

Simon’s victory in his bet with Ehrlich drove home an important insight relevant to these energy markets: scarcity and abundance are in dynamic relationship with each other. Abundance does not simply progress steadily to scarcity. Scarcity, by leading to increased prices, spurs innovation and investment.

Exaggerated fears of resource scarcity can easily lead to poor economic management, including stifling price controls, panicked efforts to limit production or consumption, and national investment strategies predicated on high resource prices that turn out to be ephemeral. In other words, excessive pessimism has a cost.

Simon treated markets as if they were separate from society, instead of a human creation, vulnerable to our collective blind spots and limitations. Many economists espouse Simon’s view that the marketplace can address environmental problems adequately, if the markets account for the external costs of economic growth. But that is a big if.

“Climategate did not begin with climate,” the free market energy scholar Robert Bradley Jr. wrote in a 2009 essay about a controversy over climate science. Bradley tied “climate alarmism” to the “neo-Malthusianism” of the 1970s.

Climate change, to the best of our scientific knowledge, is happening, and much of the recent global warming that we have seen appears caused by human actions. And climate change is a significant problem that threatens heavy economic and social costs. The world that humans are creating — with an increased likelihood of more intense storms, prolonged droughts, and profound changes to ecological systems — is not likely to bring changes that people will want. These are some of the vital insights of environmental scientists like Paul Ehrlich. At the same time, predictions that “billions of us will die” by the end of the century as a result of climate change or that civilization will collapse reenact the least helpful elements of Ehrlich-style environmentalism.

There is a serious and significant discussion to be had over what policy actions to take, and when. How much will the impacts of climate change cost, and how urgent is the need for immediate action?

Neither biology nor economics can substitute for the deeper ethical question: What kind of world do we desire?