Collapse_ How Societies Choose to Fail or Succeed - Jared Diamond [262]
Even prior experience is not a guarantee that a society will anticipate a problem, if the experience happened so long ago as to have been forgotten. That’s especially a problem for non-literate societies, which have less capacity than literate societies to preserve detailed memories of events long in the past, because of the limitations of oral transmission of information compared to writing. For instance, we saw in Chapter 4 that Chaco Canyon Anasazi society survived several droughts before succumbing to a big drought in the 12th century A.D. But the earlier droughts had occurred long before the birth of any Anasazi affected by the big drought, which would thus have been unanticipated because the Anasazi lacked writing. Similarly, the Classic Lowland Maya succumbed to a drought in the 9th century, despite their area having been affected by drought centuries earlier (Chapter 5). In that case, although the Maya did have writing, it recorded kings’ deeds and astronomical events rather than weather reports, so that the drought of the 3rd century did not help the Maya anticipate the drought of the 9th century.
In modern literate societies whose writing does discuss subjects besides kings and planets, that doesn’t necessarily mean that we draw on prior experience committed to writing. We, too, tend to forget things. For a year or two after the gas shortages of the 1973 Gulf oil crisis, we Americans shied away from gas-guzzling cars, but then we forgot that experience and are now embracing SUVs, despite volumes of print spilled over the 1973 events. When the city of Tucson in Arizona went through a severe drought in the 1950s, its alarmed citizens swore that they would manage their water better, but soon returned to their water-guzzling ways of building golf courses and watering their gardens.
Another reason why a society may fail to anticipate a problem involves reasoning by false analogy. When we are in an unfamiliar situation, we fall back on drawing analogies with old familiar situations. That’s a good way to proceed if the old and new situations are truly analogies, but it can be dangerous if they are only superficially similar. For instance, Vikings who immigrated to Iceland beginning around the year A.D. 870 arrived from Norway and Britain, which have heavy clay soils ground up by glaciers. Even if the vegetation covering those soils is cleared, the soils themselves are too heavy to be blown away. When the Viking colonists encountered in Iceland many of the same tree species already familiar to them from Norway and Britain, they were deceived by the apparent similarity of the landscape (Chapter 6). Unfortunately, Iceland’s soils arose not through glacial grinding but through winds carrying light ash blown out in volcanic eruptions. Once the Vikings had cleared Iceland’s forests to create pastures for their livestock, the light soil became exposed for the wind to blow out again, and much of Iceland’s topsoil soon eroded away.
A tragic and famous modern example of reasoning by false analogy involves French military preparations from World War II. After the horrible bloodbath of World War I, France recognized its vital need to protect itself against the possibility of another German invasion. Unfortunately, the French army staff assumed that a next war would be fought similarly to World War I, in which the Western Front between France and Germany had remained locked in static trench warfare for four years. Defensive infantry forces manning elaborate fortified trenches had been usually able to repel infantry attacks, while offensive forces had deployed