A good bit of the preceding material on causality comes from stuff I had prepared earlier for my classes (hence the perhaps lecturing tone on occasion.) But the immediate stimulus to develop this series on causality was a new book called Global Crisis by Geoffrey Parker. The book is enormously fascinating, and at the same time very depressing. In it he recounts the long and extremely horrible saga of the 17th century, when all across the world things came generally unhinged, attributable (in his contention) to the climax of the “Little Ice Age” that started about 1620 and continued until nearly 1700. A drop in worldwide temperatures of between 1 and 3 degrees Celsius seems to have been enough to trigger a nearly century-long period of violent weather extremes – floods, droughts, years without a summer – accompanied by plagues, famines, failed harvests on end (at least half of the yearly harvests failed, across the world – more in some places), etc. This was accompanied by what Parker calls the “Global Crisis” a worldwide pattern of extremely violent wars (the Thirty Years War, English Civil War), regime changes (China, Japan, India, Netherlands), and a whole batch of other horrid stuff.
There’s no question that the 17th century was worldwide about the worst sustained period of bad climate that the human race ever suffered through since the Mt. Toba supervolcano 70,000 years ago that probably took the human population down to about 10,000 individuals. And it was also a period of general social chaos, upheaval, and conflict worldwide, although there have been a lot more of them. Historians generally agree that the Thirty Years War was close to the most pointless, as well as the nastiest, war ever fought in Europe, with only World War I ahead of it for the title, which is something. Obviously, Parker sees a causal connection between the effects of the bad weather and large-scale social disruption, and spends 904 pages laying all this out in detail. Part of his argument is that by keeping the general misery level of people at record levels for so long, the weather may have increased desperation enough that it seemed better to keep fighting and maybe win something than make peace and admit that it had all been pointless.
But as we have discussed, correlation does not equal causation, and determining why the 17th century was so rotten isn’t all that simple. For example, there’s no particular way that the weather can be blamed for the Bohemian nobles’ decision to toss three men out of an 80-foot high window in the Second Defenestration of Prague, thus precipitating the Thirty Years War; or Philip IV of Spain’s religious fervor that kept his country at war continuously from 1620-1700; or Charles I’s vehement insistence on his divine rights that led directly to some 300,000 deaths in the British Isles, including his own. Nor was the weather to blame for the run of wholly inept simpletons that the Ming dynasty in China turned up as its last three emperors, or the political mess in northern India that allowed Akbar the Great to consolidate the Moghul Empire.
So maybe extreme weather – cold or hot – causes violence. But maybe it’s also true that people just like to whack on each other. Estimating the relative effects of “climate” and “desire to whack” is likely to be complicated, without a lot of “science” to guide it. There are likely to be a set of mediating and moderating factors, such as similarity of the whackers and whackees, distances between them, availability of weapons, etc., plus personal factors such as propensity of individuals to preach whacking, ideologies in favor of whacking, leadership, economics, and the like. When you’re working at the level of societies, defining “variables” becomes rather problematic. It’s one of the reasons I traded history for organizational behavior.
Some of the reasons why social violence occurs have to be purely random, or at least idiosyncratic. Why did the Mongols in the 13-14th centuries sweep through and conquer most of Eurasia almost without opposition, then basically fade away into nothingness? How did the ferocious Aztec powerhouse turn into Mexicans within a couple of generations? Why did Yersinia pestis come into being and make its first mark on the world in the middle of the 6th century, just as the Eastern Roman Empire found effective leadership under Justinian and was beginning to rally civilization and put things back together? The resulting “Plague of Justinian” not only put an end to that process but probably killed at least a third of the population of the Mediterranean area in the process. And of course again in the mid-14th century the same germ took out perhaps half the population; then largely disappeared until the 17th century; and has been largely absent ever since.
Obviously, large-scale plagues are facilitated by famine and social chaos; though sometimes it’s just opportunistic – e.g., smallpox and measles among the native Americans from the 16th century on destroyed well-functioning societies as well as the less functional (in return, of course, America exported syphilis to Europe, starting in 1493; the “Spanish pox” became the “French pox”, then just “the pox”.) But while it’s definitely the case that climate, food, and disease are all tied together, attributing “causality” to one factor or another is far less certain.