When people see the status quo as immovable, they tend to be passive even if they are themselves dissatisfied. Indeed, they may be unwilling to reveal their discontent, or to fully admit it to themselves. But once they see others visibly taking a stand, they both gain more confidence in their dissent and become more willing to act on it — and by their actions they may induce the same response in others, causing a kind of chain reaction.

Such cascades explain how huge political upheavals can quickly emerge, seemingly out of nowhere. Examples include the revolutions that swept Europe in 1848, the sudden collapse of communism in 1989 and the Arab Spring of 2011.

Somewhere ahead is a cliff: a calamitous reversal of humanity’s fortunes. Nobody can see exactly where it is, but everyone knows that at some point the bus will have to turn. Problem is, Wizards and Prophets disagree about which way to yank the wheel. Each is certain that following the other’s ideas will send the bus over the cliff. As they squabble, the number of passengers keeps rising.

Nowadays the Prophets’ fears about industrial agriculture’s exhausting the soil seem prescient: A landmark 2011 study from the United Nations’ Food and Agriculture Organization concluded that up to a third of the world’s cropland is degraded.

At first, reconciling the two points of view might have been possible. One can imagine Borlaugian Wizards considering manure and other natural soil inputs, and Vogtian Prophets willing to use chemicals as a supplement to good soil practice. But that didn’t happen. Hurling insults, the two sides moved further apart. They set in motion a battle that has continued into the 21st century—and become ever more intense with the ubiquity of genetically modified crops. That battle is not just between two philosophies, two approaches to technology, two ways of thinking how best to increase the food supply for a growing population. It is about whether the tools we choose will ensure the survival of the planet or hasten its destruction.