Extreme weather events and their consequences always offer an opportunity for reflecting on how humans think about risk and uncertainty, and the different techniques involved in attempts at the prediction or anticipation of future developments. My interest in this is twofold: partly, involvement in a Bristol research group and a conference in November on the new(ish) interdisciplinary field of anticipation, and partly my teaching and research on ancient environmental history – both of which I really need to find time to write about more. As far as the latter is concerned, my focus is less on the reconstruction of ancient environmental conditions (we have scientists for that sort of thing, and brilliant interdisciplinary researchers like Michael McCormick at Harvard) than on the human factor: how Roman culture and patterns of thought were shaped by, and in turn shaped, the different environments which the Romans colonised.
While the differences between the technological power of the Roman empire and of modern industrial capitalism are immense – you just have to look at the contrast between the power outputs and capacity for growth of an organic and a mineral energy economy, as argued by E.A. Wrigley in Continuity, Chance and Change – there is still significant mileage in comparing the ways in which complex, interdependent social systems engage with their environmental contexts, and ideas of risk and uncertainty offer an interesting case study. Or so it seems to me, on the basis of some work on what classical Roman law has to say about water and water management, published earlier this year in Sitta von Reden & Christian Wieland, eds, Wasser. Alltagsbedarf, Ingenierskunst und Repraesentation zwischen Antike und Neuzeit (Vandenhoeck & Ruprecht, 2015). This builds on the fundamental research of people like Brent Shaw on water distribution systems in Italy, Spain and North Africa; but, rather than focusing on how far legal sources can help us reconstruct the reality of such systems, my interest was in the apparent gaps between the juristic and cultural assumptions evident in those sources and what we can reconstruct of the reality that, one assumes, this legal thinking was supposed to reflect and to help manage.
This gap had been observed before – not least by Shaw, in observing the inapplicability of most of the jurists’ remarks to what epigraphic evidence reveals of the workings of water distribution schemes in North Africa – but taken as a basis for discounting the jurists as useful evidence rather than as a topic of interest in itself (beyond his suggested explanation that because the jurists spend so much more time talking about floods rather than drought, perhaps their perspective was wholly Italo-centric). But if the basic principles offered by the jurists for deciding disputes concerned with water were largely disconnected from reality – above all, the idea that, within an environment characterised by e.g. Peregrine Horden and Nicholas Purcell as “predictabily unpredictable” across both time and space, a basic principle “that the water should flow in the same way as it did last summer” was remotely workable – then that seems to be in need of explanation, and potentially illuminating about the jurists’ thinking.
My article canvasses several possible explanations, which aren’t mutually exclusive. One is entirely practical: the principle is not expected to be realised in reality, but is the basis for a magistrate to insist on the cessation of activity on either side that’s potentially damaging to the other (whether allowing flood water to drain onto another’s land or extracting too much water from a common source) as a starting-point for negotiating a compromise (while protecting the state’s interests, e.g. maintaining the navigability of a public river). The second is that the jurists allow their thinking to be dominated by a legal concept at the expense of practicality or any connection to reality – something which, according to J. Getzler’s 2004 A History of Water Rights at Common Law, happens in early modern England, despite the pressing need for a different approach in order to manage disputes between different mill owners. And the third is that this reflects broader cultural assumptions about the climate.
Ancient commentators clearly recognised variation in precipitation levels, temperatures and other climatic factors through the course of the year as well as between different places – it’s a fundamental concern of agronomical handbooks from Hesiod onwards – and the possibility of variation from year to year. But a case can be made that they assumed normal consistency over the long term, so that a year that was perceived as abnormally wet (hence floods) or abnormally dry (hence competition for scarce supplies of an essential resource) could be bench-marked against the previous summer as a norm. That seems like common sense; we too have deeply ingrained assumptions about weather patterns, inherited from our culture and reinforced by experience (and faulty memories; of course summers were always sunnier when we were young…), and – at the most general level, to the effect that summer is warmer and drier than winter in north-western Europe, for example – they are not inaccurate.
Such assumptions are not well adapted to changing circumstances – the familiar ‘boiling the frog’ problem. I think a case can be made that the Romans assumed a more consistent and predictable climate than other evidence suggests was the norm, at least insofar as they talk about the subject (so this may be a problem for the educated, intellectualising classes rather than the ordinary peasants and their basic rules of thumb, if not fundamental pessimism; bear in mind that I come from a line of Norfolk tenant farmers…). Even if not, we then have to take into account the evidence for climate change over the course of Roman dominance of the Mediterranean, and the implications of that for weather patterns – clearly, a set of assumptions developed in, say, the ‘Roman warm period’ might be rather less useful as temperatures cooled. And on top of that, the jurists took no account of other changing circumstances, such as changes in land use or demand for water; even if the water flowed exactly as it did the previous summer, this might still lead to problems if there was greater run-off from the hills or higher demand in the valleys (including from the growing cities, siphoning off local water resources through their aqueducts).
The obvious conclusion is how unhelpful everyday heuristics can be in the face of complexity, especially set against a changing context. We, and not only the Romans, operate with a set of inherited assumptions about the normal parameters of predictable variation, which are not easily adjusted even if we’re aware that we might need to – the basic problem of signal and noise, as constant minor variation in the weather makes it harder to detect long-term trends in climate that are crucially – but only ever partially – driving individual events. This is of course why we have scientists, and powerful predictive models that point to the increased likelihood of extreme weather events, the likely consequences for water run-off of grazing or maize cultivation on hills, tarmacing over the landscape, building on flood plains etc., and why we have governments advised by scientists and other technicians, who can make unpopular but unnecessary decisions in response to that advice.
The Romans had no such understanding of climate science, and so naturally failed to recognise what was happening to them as the climate changed; an exceptionally wet winter was only ever conceived as a deviation from a stable long-term norm, so the correct response was simply to restore things as far as possible to that norm.* The basic principle of “as it was last summer” trumped reality every time. What’s scary is the extent to which this remains true, despite the development of scientific understanding: governments persist in short-term thinking, preferring to skimp investment in the hope that this won’t matter rather than risk spending money on precautions that might not be needed. And so, every couple of years, along comes some more ‘once in a century’ rainfall, and its consequences are far more devastating than they needed to be. Same procedure as every year…
*There’s a whole other set of questions around soil quality, where some ancient sources do indicate awareness of the possibility of deterioration as well as erosion – even if we largely hear about this from the disparaging remarks of Columella, dismissing the idea that divine Nature can ever be exhausted by human activity…