The Fall of Rome, III: Progress Did Not Exist

There's another explanation for why the history books display that progression you mapped out: They are Dutch history books, so naturally they want to focus on the bits of history that are especially relevant to the Dutch. One should expect that the "center of action" of these books drifts towards the Netherlands over time, just as it drifts towards the USA over time in the USA, and (I would predict) towards Indonesia over time in Indonesia, towards Japan over time in Japan, etc.

This sequence was incredibly interesting while also being very short and to the point. Thanks a great deal for writing it.

Generally speaking i think your hypothesis is interesting and plausible.

A few questions

• For the narrow vs wide glass metaphor for population, does it really line up with the multi-century timelines involved? If populations can grow 2x every 20 years in these societies, wouldn't europe have filled up with people much faster? Isn't the fact that it didn't down to a lack of technology (complex agriculture and settled states able to defend agriculture)?
• How much evidence is there that concrete production fell due to lack of fuel as opposed to, say, economic collapse and constant civil wars drastically reducing demand for very expensive high-grade building materials?
• Your model of intensive agriculture seems to be "everyone knows what it is but people won't do it until it's necessary". Is this true? Isn't intensive agri a super advanced tech which took centuries to develop and diffuse? Isn't every pre-industrial society pretty much permanently at the malthusian limit, meaning everyone would already have an incentive to do intensive agriculture if possible.
• Do you think the greeks developed so quickly because they were land bound and hence had to resort to intensive agriculture? Why not other hypothesis like them being next to the sea = hugely more mobility + trade = hugely more wealth = higher pop densities and more specialization in complex good creation.

The narrow/wide bucket analogy is neat; it is a good thinking tool. That said, I am by no means a historian, and do not know how good of a model it actually is. Some scattered thoughts:

• The metaphorical bucket overflowing means unavoidable innovation, not system collapse per se. It seems to me like the narrow bucket can overflow many times, and each time it does it gets wider. That completely changes the model: no longer does it explain this 'shift towards the north'.

• As for Rome, it had long exhausted the surrounding lands before it collapsed. Its bucket overflowed many many times. One of the innovations they made is to cultivate grain in distant lands and ship it to Rome in huge quantities (Im sure they weren't the first to do this but the scale is massive). Your bucket-theory is tightly coupled to people exploiting their surroundings only, and this breaks the model completely in my opinion.

• A good source for reading in this vein is this blog, in case you haven't seen it yet. This specific article is about land exploitation from a city point-of-view, but I think it's very much related.

Thank you for the article! In my opinion, one of the main issues is that it does not seem to explain how the Eastern part of the Empire survived.

Rome was never economically self-sufficient. The city of Rome was a sink that absorbed food and products from the provinces, and produced nothing. The millions of inhabitants of Italy could survive only thanks to the subjugated provinces of the Empire.

Other areas of the Empire, notably Egypt and Gaul, were self-sufficient. In particular, Egypt was the main exporter of manufactured good (Roman travelers to Alexandria usually lamented the fact that the local inhabitant were greedy and always busy making money). In general, the Eastern part of the Empire was much richer than the West, was more urbanized, and had many more ancient and complex local administrative institutions.

When the Empire split between a Western and a Eastern half in the IV century, the Western part was in serious trouble. The only relevant food-exporting provinces left to the Western Empire was Africa. When Africa was lost, the Empire quickly fell. On the contrary, the fall of the Western Empire had no dramatic consequences on the Eastern Empire (ok, it was a big export market loss, which probably contributed a lot to the social tensions and the riots of the Justianan era; but a crisis due to a lack of an export market for your manufactured goods is way better than a crisis due to a lack of food to import).

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As concerns your chart of civilizations moving in the north, in my opinion this is only the result of a bias: we learn in school about the civilizations more relevant to our history. I do not buy your thesis that the intensive agricolture drove the rise and fall of the civilizations:

• Ptolemaic Egypt had an estimated population of about 8 millions of inhabitants, if I recall correctly. This is a great increase with respect to Ancient Egypt, and it was largely made possible by improvement in agricolture (not only plough, but irrigation and better agronomical techniques). This is after the "civilization hot spot" moved north of Egypt in your scheme - I am not sure if this count as a point for or against your model.
• I have not the time now to look for estimations of the Roman population through history, but (if you trust my half-educated guess) I do not expect a demographic boom to have took place after the Roman conquest. The Roman Empire was forged by conquest, killings and enslavements. In The Economic and Social History of the Hellenistic World (a bit aged, but highly recommended!), Rostovtzeff speaks on the contrary of "race suicide" describing the demographic decline of Greece in the II and I century BCE. The parts of the Empire that were already civilized before the Roman conquest (namely Greece and the Near East), already had infrastructures and institututions before the Romans, which were ofted of superior quality (example: the celebrated Roman aqueducts worked by gravity, while e.g. the city of Pergamon in 180 BCE had watertight metal pipes which lifted water over a difference of altitude of >100 m. Also, the Roman aqueducts were designed by Greek slave engineers; the Romans never learned to project them on their own. Once the last educated Greek slaves dies, they could not buy anymore aqueducts. I hope that this specific example clarifies the general trend); and on top of this, after the Roman conquest, they also had to feed an economically parasite overlord. So I do not expect the population of the Eastern part of the empire to have substantially risen durin Roman rule (also Wikipedia says that it decreased, but I did not verify the sources). On the contrary, the population did probably rise (after the initial mass slaughters) in the formerly sparsely populated regions of Northern Western Europe; but these are also the provinces that in your chart became more relavant for civilization after the fall of Rome, so this does not seem to advance your theory.
• There is no way in which Charlemagne's empire was more relevant than the Umayyad Caliphate in 800 AD , in any reasonable "civilization" metric.
• Southern Europe was economically more developed than northern europe until the XVI century, and while the causes that reversed this pattern are object of debate among scholars (I recommend this paper), I do not recall seeing soil depletion as a proposed cause (instead, the shift in global trade route and the centralized governments likely played a role).

I would point to a different cycle to explain the fall of Rome. Set this against both the Malthusian trap theory and the (many) theories around technology. This is an institutional story.

One of the key problems that the Roman state failed to solve was that of who rules. The Republic was semi-successful at this. It used public recognition and generational advancement in social class as its main methods of controlling elites. This ultimately failed after the Carthaginian wars eliminated the external enemy that kept internal politicking in check. At this point you see a continuous cycle of ambitious elites conquering new territories in the name of Rome and — this is critical — enriching themselves massively and using that fortune to control the Roman state. This led to the civil wars. Ultimately, Octavian triumphed — to my mind, he was the best that Rome could hope for in the circumstances, but he did not really fix the core problem. 

After Augustus, the problem became more specific: the succession. The civil wars had shown that the way to control the Roman state was the control armies. Much of later Roman history is essentially a story of charismatic generals fighting for control of the state. It is the interludes in that story that are most important, though. These are when some great general prevails and stays in office long enough to carry out major reforms. Think Diocletian and Constantine.

History books seem to love these “reforms.” Economists hate them. These reforms — unlike those of Augustus — were entirely about capturing more resources for the state, so that the victorious general and his descendants would be better able to fend off competitors. But even the best of Roman’s economy did not produce massive surpluses. So extracting more was difficult. Near the end, the cost of empire was greater for taxpayers than the benefits. This explains why laws would literally mandate that every son follow his father’s occupation using his father’s property: so that the tax man would know from whom to collect. This eventually becomes feudal serfdom, where peasants were tied to the land.

In a setting where private initiative is so burdened with crushing taxation and repressive regulation, is it a surprise that economic growth reverses or that technological innovation becomes limited to agriculture?

I think that this story has more explanatory power than the energy-constraint story does. But it might compound the energy-constraint story. One of the fundamental problems with seeing energy constraint as the empire-killer is that scarcity of a resource should drive up its price. That should incentivize lots of interesting behaviors: long-distance trade, product substitution, process substitutions for technologies that use less of the resource, etc. We see this in the industrial age’s move from charcoal to coal to oil to electricity. We don’t see that in Roman times. Why? Perhaps because the central government fixed the prices of everything so that it would be easier to collect taxes. If the price of charcoal doesn’t increase when supply decreases, we miss out on all of the incentives that a freer market would have brought. 

So governing institutions are a key component of why Rome fell, because they caused a ratchet effect of ever-increasing tax and regulatory burdens.

This causes me worry about modern politics. On a precautionary principle, it seems to me that we should look askance at the ever-increasing regulatory burdens on business. If they cause civilization to be less effective at producing technology that can save civilization from whatever would cause its fall (asteroid, supervolcano, disease, global warming, whatever), that seems like a bad deal. The fact that, after a fall from civilization, humanity cannot climb the same ladder it did before because it has exhausted all surface-level minerals means that —unlike Rome — this is probably our last shot at assuring super-long-term survival of the human species. So I'd prefer less regulation that we currently endure.

I should note that my final conclusion highly correlates with my priors, so is suspect.

While the lack of fuel was a serious concern to the Romans (even during the time of Augustus), I don't think either the population pressures or the lack of fuel had much of an effect on the decline of the Empire.

After the 3rd century, Rome was more likely to face under population than overpopulation. It was estimated that the Crisis of the 3rd Century led to the deaths of about 1/3 of the Empire. Afterwards, (particularly in the West) the severe lack of people led to the development of the patronage system. That was one of the reasons why Rome couldn't defeat Alaric in 410, they had no available people.

Also, for the most part, Rome was "full" even during the peak of the Empire. For the most empty provinces, Gaul and Hispania, they were empty not due to the lack of people, but due to the lack of arable land. The technology to start tilling the hard soils of northern Gaul wouldn't be invented until the 10th century. So the late Empire wouldn't have faced any more population pressures than the Empire of Claudius or Nero.

And finally, the lack of fuel was also a problem during the peak of the Empire. I've once heard (though I don't have a source) that much of the German economy was selling fuel to the Romans circa 100CE. But besides that, the Romans had other alternatives to wood, such as how coal was often used by blacksmiths.

Oh, also I wouldn't say that history has "moved" north overtime, just that the history of the predominant "western" empire has. If looking at the most powerful and/or sophisticated state overtime, the focus of history would constantly move between Egypt, Anatolia, Persia, Northern India, and Southern China for most of history. I think the main western empire has moved overtime simply because it can't go south, west, or east (because of the Sahara, Atlantic, and because if it went East, it wouldn't be considered western anymore).