Whatever each culture grows and manufactures cannot fail to be here at all times and in great profusion. Here merchant vessels arrive carrying these many commodities from every region in every season and even at every equinox, so that the city takes on the appearance of a sort of common market for the world.

Your farmlands are Egypt, Sicily, and all of cultivated Africa. Just as there is a common channel where all waters of the Ocean have a single source and destination, so that there is a common channel to Rome and all meet here: trade, shipping, agriculture, metallurgy— all the arts and crafts that are or ever were and all things that are produced or spring from the earth. What one does not see here does not exist” (Aristides, The Roman Oration).

The ancient Roman empire hosted massive cities whose growth relied on large and growing agricultural surplus shipped in along trade networks spanning thousands of miles and tens of millions of inhabitants. It saw centuries of per capita income growth, technological advances in hydraulics, metallurgy, agriculture and transportation, and stable governance that respected property rights.

Adam Smith said “Little else is requisite to carry a state to the highest degree of opulence from the lowest barbarism, but peace, easy taxes, and a tolerable administration of justice.” Rome had all of these and more, but yet did not succeed in cultivating an industrial revolution.

Why not? What was the binding constraint on a Roman industrial revolution?

Coal and Cotton

Historian and blogger Bret Devereaux writes about the lack of Roman industrial revolution here. His basic strategy is just to read into the one data point we have on industrialization: Britain. Could Rome have replicated the precursors to industrialization found in Britain?

It is particularly remarkable here how much of these conditions are unique to Britain: it has to be coal, coal has to have massive economic demand (to create the demand for pumping water out of coal mines) and then there needs to be massive demand for spinning (so you need a huge textile export industry fueled both by domestic wool production and the cotton spoils of empire) and a device to manage the conversion of rotational energy into spun thread. I’ve left this bit out for space, but you also need a major incentive for the design of pressure-cylinders (which, in the event, was the demand for better siege cannon) because of how that dovetails with developing better cylinders for steam engines.

Putting it that way, understanding why these processes did not happen in the Roman world is actually quite easy: none of these precursors were in place.

It is not clear to me that there is a plausible and equally viable alternative path from an organic economy to an industrial one that doesn’t initially use coal (much easier to gather in large quantities and process for use than other fossil fuels) and which does not gain traction by transforming textile production.

Devereaux’s strategy of using Britain’s case to guess the necessary and sufficient conditions for industrialization is reasonable given how few samples we have. However, I don’t find his conclusions from this data point convincing.

Most directly, it just seems false that Rome had none of the precursors present in Britain. For one thing, Britain was part of the Roman empire for more than 300 years, along with all of its coal deposits. Outside of Britain, lots of large coal deposits were available to the Romans.

Map of European Coal Deposits Source

There were massive mining operations in southern Spain and Britain. Pumping water in and out of these mines was an essential part of their mining techniques, and they built complex water-powered machinery to do so.

Sequence of wheels found in Rio Tinto mines

There was demand for coal in Rome as a heat source and demand for spinning power in several of Rome’s most important industries. Rome had factories for firing pottery, some capable of firing 40,000 pots at once. So many amphorae of olive oil came to Rome that their shattered refuse formed a mountain made of 53 million+ pots that still exists today. Fuel for firing the pottery industry of Rome is a source of demand for coal.

Monte Testaccio

Using coal for heat isn’t sufficient to get ancient Romans interested in steam engines, though. For that, you need a reason to transform heat into rotational power. Devereaux claims that only textiles are sufficient for this purpose, but there were other large industries in the empire which required lots of rotational power. Mechanical grain mills powered by stacked water wheels fed tens of thousands of people. They also used rotational power to run sawmills, water pumps, bellows, and ore hammers.

Barbegal mills

The Romans do seem to have been much further behind on textile manufacturing technology, but they had plenty of coal and lots of uses for it, including good reasons to translate its heat into rotational power.

Tech Tree Ordering

Jason Crawford explains the lack of Roman industrial revolution the same way one would explain the lack of Roman AI industry: they simply weren’t far enough along the tech tree.

Here are a few of the things the ancient Romans didn’t have:

• The spinning wheel
• The windmill
• The horse collar
• Cast iron
• Latex rubber
• The movable-type printing press
• The mechanical clock
• The compass
• Arabic numerals

And a few other key inventions, such as the moldboard plow and the crank-and-connecting-rod, showed up only in the 3rd century or later, well past the peak of the Empire.

This is a useful point and a counterbalance to the implication I made in the introduction to this essay. Despite some backwards movement during the dark ages, technological progress is mostly cumulative and there were several important advances that Europeans had in the 1700s which weren’t available to the Romans. Cast iron and the printing press in particular seem like strong candidates for a missing link that would have prevented a Roman industrial revolution no matter how large and advanced other parts of the economy became.

I do think this explanation underrates the uncertainty around our estimation of Roman’s possession of these technologies. All surviving primary source text from Rome could easily fit on a 10-year old thumb drive. The archeological evidence and text we do have is a lower bound on the extent of Roman knowledge, not a central estimate. The dates assigned to the earliest known example of the technologies in Jason’s list can only be pushed backwards and there are isolated examples of advanced machining and gearing like the Antikythera mechanism that raise the lower bound of technological sophistication.

This explanation also only shifts the reason why the Romans did not industrialize one question deeper. After accepting that the Romans do seem to have lacked important pre-cursor technologies, we then ask why these earlier technologies were not already discovered and face a similar question as we started with. Rome was clearly within reach of all of the technologies on Jason’s list. They had easy access to all the necessary inputs and clear use cases for each technology. The only thing they lacked was the ideas and a culture which produced them and supported their spread.

Slave Labor

The traditional connection of slave labor to industrialization is connected to labor costs. It’s the inverse of Robert Allen’s hypothesis that mechanization in Britain started because of high wages for human labor. In slave societies like Rome, wages are always low.

This explanation has never made much sense to me. Slave labor or not, labor was the number one cost in the production of all major goods in the Roman economy. This explanation would suggest, for example, that southern slave states in the 19th century would not be interested in the cotton gin, because wages for slaves were low. But the cost of slave labor to plantation owners was still a large fraction of their total input cost, so economizing on that fraction is important to them. Similarly, in a Roman economy where a huge fraction of GDP goes towards labor, increasing labor productivity must be very valuable, regardless of whether it is slave labor or not.

Where I do see an avenue for slavery to have a large effect on the chance of industrial revolution is through the parasitic, maladaptive culture it promotes.

Culture

Mark Koyama reviewing Aldo Schiavone’s The End of the Past has several interesting quotes on the cultural impact of slavery and the cultural explanation for Rome’s missing industrial revolution in general. The main disincentive for improving the work of slaves was not the lack of financial reward, but the lack of cultural approval for such work.

The relevance of slavery colored ancient attitudes towards almost all forms of manual work or craftsmanship. The dominant cultural meme was as follows: since such work was usually done by the unfree, it must be lowly, dirty and demeaning.

Successful merchants or businessmen who might invent improvements to their production process instead preferred to emulate the aristocratic classes and become slave-holding farmers.

The phenomenon coined by Fernand Braudel, the “Betrayal of the Bourgeois,” was particularly powerful in ancient Rome. Great merchants flourished, but “in order to be truly valued, they eventually had to become rentiers, as Cicero affirmed without hesitation: ‘Nay, it even seems to deserve the highest respect, if those who are engaged in it [trade], satiated, or rather , I should say, satisfied with the fortunes they have made, make their way from port to a country estate, as they have often made it from the sea into port. But of all the occupations by which gain is secured, none is better than agriculture, none more delightful, none more becoming to a freeman’

The cultural force against the mechanical arts is both upstream and downstream of technological progress. The printing press, for example, plays an essential role in creating the culture of invention and tinkering in northern Europe preceding their industrial revolution. The lack of widespread literacy and the fact that a large portion of the population were themselves slaves, with little incentive to invent anything since any surplus they produce is captured by their masters, made the development of an innovative culture impossible.

There was no culture of invention and discovery, no large population of skilled tinkerers or machine builders, and no evidence of labor scarcity that might have driven the invention of labor-saving inventions.

Considering each of these theories I come away thinking that the Roman industrial revolution was certainly possible and that the printing press is underrated as the primary and perhaps sole constraint.

The Romans were only a few “wheels on suitcases” level ideas away from each of the technologies on Jason's list. The printing press in particular would not have taken any new materials or even much design given the profusion of wine and olive presses across Rome.

The printing press alone may have been sufficient to start a Roman industrial revolution because its effects on culture are upstream of the invention processes that might invent all the other required tech. There was more than enough scale in the economy of Rome to support capital intensive productivity improvements in their major industries. So the major constraint must have been idea generation. Rome punches below their weight in population on this metric because of an aristocratic, slave based culture that ridicules the mechanical arts. If copies of Vitruvius or Archimedes became cheap enough that even the workers close to the vulgar arts of farming and manufacturing could read them, it would surely have an effect on the cultural attitudes that stultified Roman invention.

Wheels and suitcases co-existed for hundreds of years before being combined, so even though the Romans may have been close to these inventions in idea space, it could still have taken centuries. Fertility decline, political collapse, and military conflict snuffed the candle before it could fully catch.

Beyond its inherent interest, the question of a Roman industrial revolution has implications for the future. If Rome could have begun the industrial revolution fifteen hundred years earlier, then its failure to do so was a transparent tragedy: An unnecessary millennium of poverty and suffering that was near impossible to see while it was happening. No one at the time understood the potential prosperity they were missing out on. Understanding the unfulfilled potential of industrialized Rome counsels us to be more vigilant about identifying and pursuing opportunities for transformative technological and economic progress in our own time, lest we too inadvertently delay the next step forward in human prosperity.