Macfarlane on Causation

John Jay’s post, below, entitled Terms and Models discusses the mental models people develop to understand the world in a non-mathematical way which is based generally on the weight to be given to various variables in a partial differential equation, and it reminded me of something I had read by Alan Macfarlane. The best discussion I have seen of the idea of multiple- rather than mono-causality, with the added complication of weight for each link, and the timing of each link, is in the remarkable concluding chapter to Macfarlane’s The Savage Wars of Peace: England Japan and the Malthusian Trap. The book is excellent, and I unequivocally recommend it.

Macfarlane’s discussion of “chains of causation” is similar to John’s. An early draft of the chapter containing Macfarlane’s pertinent language is available online. The chapter is entitled How it Happened. Macfarlane set out to explain how both England and Japan had escaped the “Malthusian traps” of war, famine and disease that afflicted other countries. He found that “[o]ne of the central problems in this work has been the fact that most of the effects I am trying to explain are caused by multiple and often extended chains of causation.” Macfarlane found that even apparent one-link chains, like the use of cotton clothing leads to a decline in typhus, or islandhood leads to a minimum of warfare, proved to be less simple on closer examination. He noted that many of the examples in the book contained two-link chains, e.g. tea drinking requires boiling of water, leading to minimizing of dysentery. Usually, the outcome was not intended. The consequences occurred downstream, by happenstance. There are, of course chains of many links. Then, there are also links which lead to two or more branching links, multiple results: “Tea drinking probably had a doubly beneficial effect because it both necessitated boiling and contained a bacteriostatic substance. Cotton clothes both allowed and indeed encouraged frequent washing with boiling water and also, in contrast to wool, consists of a vegetable fibre which gives lice a less attractive home.” Furthermore, “Another type of complexity is caused by the fact that each part of each chain is usually affected simultaneously by several different chains or contextual features. It is only when causes act together that they have the effects they do.” There is also “symbiosis”, and “feedback loops”. Macfarlane then tells us that as the researcher digs deeper, the hazard now becomes not over-simplification, but losing the thread of the investigation in a maze. He then steps back and says that at the end of his investigation he concluded that there really was one basic, most important reason for England and Japan escaping the Malthusian trap: Islandhood. But in the process of investigation, in particular by a process of comparison between the two countries, he had identified many of the mechanisms, the major sub-contributing phenomena, that led to the outcome of the “escape” from the Malthusian boom-and-bust cycle, and an incrementally increasing level of wealth and welfare for the two island communities of a kind which was extremely uncommon in world history.

Macfarlane concludes:

A further implication is a warning to the historian. There is always a strong tendency to impose a pattern on the past and to assume that because things occurred as they did, they had to do so. There appears to be design necessity, even calculation. As Chambers noted long ago, ‘changes in the long-term trend of population appear to have sprung from forces that were, for an economic point of view fortuitous’. It was not merely from an economic point of view, however. I cannot do better than end that what happened was not only a gigantic accident, but also an enormous exception. It was a miracle that ought not to have happened, nearly did not happen, yet by a set of coincidences and chances, did happen – twice. The point is well made by Mokyr. ‘The study of technological progress is therefore a study of exceptionalism, of cases in which as a result of rare circumstances, the normal tendency of societies to slide towards stasis and equilibrium was broken. The unprecedented prosperity
enjoyed today by a substantial proportion of humanity stems from accidental factors to a degree greater than is commonly supposed’.

This conclusion loops us back around to the Hayek quote in the last post.

The modern world arose for reasons our predecessors neither intended nor understood. We should be humble about attempts to “fix” apparent problems, both in terms of what we can accomplish, and due to the inevitable unforeseeable consequences. On a related point, we should be aware that immense changes in our social order will inevitably flow from the rapid technological changes we are undergoing now.

This leads us to a practical question, in the guise of a philosophical one. On what basis can we root ourselves and our actions, personally and collectively, as we face the changes ahead, the gale-force changes that will be sweeping the world, for both good and ill?

I leave the answer as an exercise for each reader.