Ian Morris’ Why the West Rules – for now (ii)

The Index of Social Development devised by Ian Morris awards precise numbers for the social development of both West and East at different times in the past.  Being incompetent at maths, most historians are disinclined to crunch numbers and feel vaguely uneasy about attempts to do so in a meaningful way. But this is no reason not to take Morris’ Index seriously, and it may be worthwhile to consider the role of numbers in the argument he develops.

One area in which he compares West and East is in the simultaneous growth of Christianity and Chinese Buddhism in late antiquity. He holds that in the 310s a quarter of the population of the Roman Empire were Christians; while we cannot be sure, most scholars would put the proportion at considerably below this. But the statement that ‘Over the next eighty years the rest of the population turned Christian’ cannot be true. Well into the sixth century we hear of a bishop in Asia Minor baptizing 70 000 or 80 000 people and large numbers of unbaptized peasants in the West, not to mention sizeable Jewish communities. Hence, while Morris is able to credit Christianity with a constant growth rate of 3.4%, my guess is that it was a good deal lower than this, and that any attempt to compare it with the growth of Chinese Buddhism, alleged to have been 2.3% per annum, likely to be invalid.

Of course these matters are tangential to Morris’ main argument, but the doubts they raise about how data can be quantified persist in areas more central to his concerns. It may seem sensible to extrapolate as he does from the size of towns and cities to their populations. But although, on his own reckoning, three-quarters of the population of Rome had left by 450 (again this figure strikes me as more precise than than the sources would allow), they remained within the old walls of the city, just as the much diminished population of Constatinople did in the late middle ages. In other words, urban populations can be dispersed or concentrated (think respectively of North American and old European cities), and arguing for population size on the basis of spread seems hazardous. Again, some of the data for literacy go beyond what I’m comfortable with. Crediting males in the time of the Roman Empire with a score of 4.25 for literacy obscures very lively debates on this very subject, and assigning females a score of 1% of that of males seems whimsical.

Hence I suspect that the numbers produced in this book, while satisfyingly precise, are not as firm as we would like them to be. This has serious consequences, because for Morris they do more than indicate a rough size and shape. The number 43 is significant, for it represents a ceiling that civilizations were unable to go beyond before beginning to use energy from fossil fuels (its status may be predictive as well as descriptive). But I’m not sure about how we arrived at this number. Hence, while full of admiration for this book (see previous posting), I’m sceptical about some of its claims.

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