Thursday, December 16, 2010

Malthus, Trajan, Alexander, Adrianople: Why Not Think About Them Together, With Math?

Chris Wickham, one of the best historians working today, spent most of the last two decades working on two books to cover the period alternately called "Late Antiquity," "the Dark Ages," or "The Early Middle Ages." (Amongst others that could as easily include, "the period when barrels took over from amphorae.")

Of all the things that Wickham stresses in these books, I am singling out the terminological problem because it suggests two visual aids to me, which I will inflict on you if you like on the way to making this tenuous connection between the first of the Five Good Emperors, and the great prophet of catastrophe.

 The first is the electron probability distribution function. (Check out the pictures!) This is the traditional quantum mechanical conundrum that electrons can only exist at discrete ranges of distance from atomic nucleii. The curves here show that they can't exist at certain distances, then are very unlikely to exist just after that distance, are more likely to exist later on. The completely misleading physical analogy is that an electron just poofs into existence in a "well," and then climbs a hill of increasingly unlikeliness towards infinity, then, poof, disappears, only to reappear a little further out in the next well. The analogy is misleading because these are just graphic demonstrations of fairly complex mathematical results. They don't even have to be real, as opposed to epiphenomena of our math. (Though the probability is that they are "real" at  a level that we can't really grasp with out sensuous intuition. So there.)

"Late antiquity" is one well in which we find our electron of historical attention; the "early middle ages" is the next. What happens between? Either the electron goes to infinity at vertical slope (there is a year in there where History is Impossible?), or our method is failing us as a way of getting at reality.  Well, okay, interesting. It's discontinuity.

That's where my other analogy comes in. Spline fits aren't at the conjunction of high culture and higher maths, like quantum mechanics, but they can come in very helpful to an engineer who has an irregular shape to model with a function (imagine a machine-driven statue/ship's hull/aeroplane wing polisher. There needs to be an equation to tell the brushes how to move, but no equation exactly models the object for whatever reason. So we will make one!)  Now, no spline fit is perfect. It will tend to grind our statue at one point, and glide over it at another. So we try to make it more accurate, by "fitting" it to more points along the surface. But Nature kicks back. The more points along the surface we get our spline curve to match, the  more wildly the spline fit deviates between those points. If we got a spline fit for every point distance ε along the surface, then as ε goes to zero, the apex of the spline curve over that interval δ will go to infinity! There's not one discontinuity between Antiquity and the Middle Ages, but rather an infinite number of them. And this is true even in a case where the individual sections of the surface we are following actually are continuous function. Because we don't know the patch-up points, our fit is wilder than it has to be.

The moral of the story is that when we try to achieve the spurious certainty of a perfect theoretical fit to an unknown period, reality kicks back. And now, like any historian, having deduced my moral from circumstances having nothing to do with history, I shall proceed to impose it on events.

So, that Malthus. Setting aside what Malthus actually says, he is the man for the "Malthusian crisis." As we understand the concept, it is a period when human population growth outstrips resources, and there is a massive human die-off. Paradoxically, the events we know best as die-offs, such as the Black Death and the Irish Potato Famine aren't Malthusian crises. They come about as a result of exogenous factors in the form of super kickass diseases. (Supposedly. Blah.) So where are our endogenous historical crises that tell us that Malthus works? The fall of Rome, pretty much.

When the Antique State collapsed and things very suddenly got a great deal less complex, more or less everywhere in the Roman world. Big things happen, and it is at least arguable that population fell. I don't think anyone much after Malthus thinks that it was "Malthusian," because, again, we don't get Malthus. (Malthus: the barbarian north, being poor, overpopulated easily. Meanwhile, the Roman Empire, being rich, overpopulated only once the structures of moral education had first collapsed. In the one, overpopulation led to the export of large numbers of persons with highly developed martial skills. In the other, they just sat around enjoying bread and circusses. Not coincidentally, the Christianity of the Late Roman Empire was "high church.")

Of course, we all know this: the Roman Empire was "decadent." Except as we learn fairly early on, the true decadent part comes during the latter years of the Julio-Claudian Dynasty (34BC--69AD). Then comes good emperors, then strong ones, and then, only after the Battle of Adrianople in 378AD, more than three centuries after the death of Nero,the end. The libertarians revisit this model, via Toynbee, and portray the late empire as a totalitarian Dominate" and make it a happy ending, but, really, details.

Now, there have been, of late, a whole series of books about the fall of the Roman Empire, enough that we could have a swinging argument about whether the Empire was deeply sick in 377, whether it was actually doing just fine until quite a bit later, or whether it was a strong state crushed by unprecedented reverses beginning with Adrianople. But I would like to point out another book. Now, Lord knows, Walter Goffart can be a difficult guy, and that he argues pretty tenuous positions pretty vehemently. But that's because he's often right, and let's cut to the chase. Why not focus on the possibility that the Late Antique Historians are feeding us a line about things like the Gothic invasions that can be unpeeled by assuming that they are self-consciously lying about very basic things in order to promote a political agenda?

Consider again the three positions about What Went Wrong after Adrianople. Why should we assume that they are so different? After all, I wasn't alive in 378AD. But my historical consciousness does include an "everything going wrong" moment: September, 2008. And I remember very clearly what happens: a sudden revising of our experience of the last few years; the humbling acceptance that it had gone wrong back then, and that we would now have to pay.

If we apply that analogy to the "fall" of the western Roman Empire, we get a picture of a fairly shortrun phenomena. In September 2008, it was the American housing bubble and the financial shenanigans around it. In 378AD, it was ..something. In September 2008, we looked back at the "recovery" from the recession of 2000 and questioned our actions since. Everything before that really was a different story. Maybe, by the same token, we should not trace the sequence of events that led to the fall of the west back to the roots of the Empire. The very health and strength of the Empire in the 300s becomes an indication of an emergent asset bubble (or whatever), perhaps beginning no earlier than 330AD.

In which case, there is not just one Roman Empire, but several. The point here is that if we see the Empire as a unitary thing, it builds up a lot of momentum going forward. And we ask how 500 years of stability collapse over one event. It we're illegitimately patching over the break points in the smooth functions, things get a little more understandable.

Now, the basic outline of the empire's history as I have already given it is well known. The momentum story is easy to write: from Augustus to Tiberius, almost a full century of stability. That's a lot of stability. Then a wild ride of judicial murder downwards and coup d'etat upwards followed by civil war, which looks like the wheels coming off, but keeps reverting to normalcy: first Vespasian establishes a new dynasty; then the Five Good Emperors; then the Severans. Sure, there is a period of complete chaos as barbarians overrun the empire, but maybe that is purely exogenous. The latent reserves of social stability suffice to throw up the Tetrarchy. We can read this as a  continuous downwards trajectory, or single out a specific point where it all goes wrong. ("High Church! High Church!" shouts Tom from the corner.)

But what if, at every conjuncture, we have instead a lurch towards disaster followed by a new political order? No momentum, no long running stability. Just one faction after another taking over and patching up the money well enough to keep it going for another generation. We'd even see party-political patronage factions if anyone was honest enough to name the people behind the coups, perhaps. But they don't, because those who won have no interest in asking whether Claudius was innocent in the fall of Caligula; Vespasian in the fall of Galba, Hadrian in the succession to Trajan?

Italics mine because Trajan is in many ways the greatest of the emperors, conqueror of vast dominions and restorer of Rome. And yet it is all too easily forgotten that he also precipitated an unprecedented collapse in the east. Literally no Emperor gave up more territory than Trajan, even if he had just conquered it. (Although the retreat from Trajan's other conquest in Dacia, much later, comes close.) It's also intriguingly the case that no emperor more than Trajan followed in the footsteps of Alexander more nearly. Trajan even sent a letter to the Senate bemoaning the fact that he was too old to conquer India, like Alexander.

Why is this important? How am I going to tie this exercise together? Heh. I don't have too. It's a blog. But consider this: we only know about Alexander because of historians who wrote in Hadrian's time, under Hadrian's patronage. Now, I don't think that there was ever a conspiracy to suppress all earlier histories of Alexander in favour of the ones produced by Hadrian's court. Precisely the contrary. The dominance of the Hadrianic picture of Alexander, and of the Julio-Claudian dynasty is a result of the regime pushing their interpretation into manuscripts available everywhere in the world, so that people neglected the others. We hear the Hadrianic version because it was shouted so loudly as to drown everyone else out.

This is wild speculation on my part, but the fact is that we have an overwhelming lesson from the surviving Alexander literature: "Western" conquerors of the Persian east were making a mistake that would come back to bite them. I can't imagine that this was consistently promoted in the earlier histories, the ones, for example, promoted in the times of the Seleucid successor state. But it sure does excuse Hadrian evacuating Trajan's conquests and executing certain other candidates. It's almost no more than accidental; a bit of spin too-well preserved. But that's how history gets distorted.

So here's the reason that our attempts to map the Roman empire to a theoretically-predicted curve keep going to infinity. It's not a single curve. It's a whole bunch of curves, with the break points papered by ancient historians. If we can identify the particular curve that we are following through the conjuncture of 378AD, perhaps we can get a theory out of it. Heck, maybe it will be a  housing bubble. (Right now, I'm plumping for a collapse in the demand for Roman (silver) money, particularly in North Africa and the frontier provinces, but I'm not exactly committed to it or qualified to defend it).

In general, I think, we'll probably understand the history of the Roman Empire, and get rid of our "Fall of the West" discontinuity --of a great number of discontinuities-- when we get under the patches. The fact that we haven't has a lot to do with the fact that we love us our crises: Malthus' ever-pregnant legacy of fear of the poor and swarthy, still distorting our science. But also because of a two-century tradition of being too nice to the Five Good Emperors, and perhaps above all of mistaking Hadrian for Trajan's dutiful and loving successor  -itself testimony to the success of Hadrian's spin --and, perhaps, of some powerful brain surgery carried out deep into our historical consciouness made with the sharp, sharp tool of Alexander the Great.

Hey, be careful up there! It tickles! Ooh, smell of rosesfsfad

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