This subject has been kicking around the Internet since the Internet began, and it’s been kicking around my head since long before then. It doesn’t seem to be an area of study for professional historians, but regular people seem to be pretty obsessed with it. My knowledge of Roman history is limited, but I think I have a take on the question that most people have not stumbled on. The following is a rant rather than a scholarly article, so there are no footnotes, citations, or attributiuons. You’ll just have to imagine those.
Most of the arguments I’ve seen on this are either circular, off point, or just plain dumb. I have seen people write that the Romans could not industrialize because they did not have advanced mathematics, didn’t use coal as a power source, didn’t have the steam engine, didn’t have the printing press to disseminate technical knowledge, and a host of other roadblocks. Depending on when you count the start of the Industrial Revolution, some of the arguments I have read seem to prove that England couldn’t industrialize in the 1700’s. But it did, despite the roadblocks that it faced. Rome must have faced a roadblock to industrialization that England did not.
To figure that out, it’s a good idea to review the reasons that are generally agreed on for why industrialization did happen in England in the 1700’s. These sets of preconditions come from various Wikipedia entries and are probably reasonable lists:
High levels of agricultural productivity (the British Agricultural Revolution) to provide excess manpower and food
A pool of managerial and entrepreneurial skills
Available ports, rivers, canals, and roads to cheaply move raw materials and outputs
Natural resources such as coal, iron ore, and waterfalls
Political stability and a legal system that supported business
Financial capital available to invest
And this set, a variation on the 6 above:
The period of peace and stability which followed the unification of England and Scotland
There were no internal trade barriers, including between England and Scotland, or feudal tolls and tariffs, making Britain the "largest coherent market in Europe"
The rule of law (enforcing property rights and respecting the sanctity of contracts)
A straightforward legal system that allowed the formation of joint-stock companies (corporations)
Free market (capitalism)
Geographical and natural resource advantages of Great Britain were the fact that it had extensive coastlines and many navigable rivers in an age where water was the easiest means of transportation and Britain had the highest quality coal in Europe. Britain also had a large number of sites for water power.
Yet another set:
It had a dense population for its small geographical size.
Enclosure of common land and the related agricultural revolution made a supply of this labour readily available.
There was also a local coincidence of natural resources in the North of England, the English Midlands, South Wales and the Scottish Lowlands. Local supplies of coal, iron, lead, copper, tin, limestone and water power resulted in excellent conditions for the development and expansion of industry.
The damp, mild weather conditions of the North West of England provided ideal conditions for the spinning of cotton, providing a natural starting point for the birth of the textiles industry.
The stable political situation in Britain from around 1689 following the Glorious Revolution, and British society's greater receptiveness to change (compared with other European countries) can also be said to be factors favouring the Industrial Revolution.
Peasant resistance to industrialisation was largely eliminated by the Enclosure movement, and the landed upper classes developed commercial interests that made them pioneers in removing obstacles to the growth of capitalism.
Most historians seem to agree that there were 6 preconditions for industrialization in Britain (though they apparently don’t agree on which 6). Looking over the lists, it is difficult to find any item that existed in eighteenth century Britain that did not exist in second century Rome. Some seem to argue that there was something unique about the land of Britain itself that was a critical factor for industrialization to begin. They are ignoring the fact that Britannia was a Roman province in the second century. The rivers, the coal, the ore, the ports, the climate, and the roads were all there in the second century just as they were in the eighteenth.
Political stability, like there was in England after the 1689 Glorious Revolution, is usually listed as one of the preconditions for industrialization. Rome had a similar period of political stability spanning from Vespasian through Marcus Aurelius. Rome had rule of law, though the limited liability joint stock company was not a construct they had available. But Rome did have a transportation system comparable , or even superior to, the one available in eighteenth century England. England had a unified market across the British Isles, but Rome had a unified market across the Mediterranean world: Western and Southern Europe, North Africa, and the near East. Products manufactured in Gaul could be sold just as easily in Egypt as in Italy.
Even more, Rome was already producing some products on a large scale by the second century CE. Using proto factory systems, pottery was being manufactured in large quantities and shipped throughout the empire. Grain was harvested in Egypt and shipped to Rome to feed a population of nearly a million people. Olive oil and wine was being produced and shipped in vast quantities (100,000 liters of olive oil from Libya per year). Gold mines active in Spain were producing 9000 kg of gold per year.
In general, technology was not a limitation for the Romans either. The water wheel was known to them and there were multi stage water wheel mills used for grinding grain in Gaul and in Italy. Water wheels were even used to pump out excess ground water from mines. Architecture and construction, not just of monuments, but of port structures and transportation facilities were a Roman specialty. Anyone who has stood under the oculus of the Pantheon in Rome would not question their technological capabilities (I have never stood in the Pantheon, but I read that it’s awesome).
Second century Rome had most of the elements that are generally considered to be preconditions for Industrialization. In some of the elements, they were more advanced than the English of the eighteenth century. But the Romans didn’t put things together to achieve industrial liftoff like the British did. There had to be something blocking the Romans that the English did not face. That something was slavery, and it blocked Rome on both sides of the equation.
It’s not known exactly how extensive slavery was in second century Rome, but estimates are that a third of the population consisted of slaves. There was likely a wide variation of the percentage by location, with some areas having fewer slaves and some having a larger share. But slave labor was used extensively in all endeavors. It was common enough that for any problem that required more labor input, or increased productive output, the answer was usually more slaves. A need to produce more agricultural output would not have created a need for new agricultural technologies. Instead, it would have created a need for more slaves, using the existing methods. This was true for manufactures as well. A need for more pottery or mine output would not have generated a need for new manufacturing or mining technologies, it would have generated a need for more slaves.
This is one critical difference between second century Rome and eighteenth century Britain. In Rome, there was a robust slave trade, and foreign wars were generating a steady supply of new slaves, In England, there were no slaves and no possibility of getting any. There was a natural supply of laborers coming from the rural farms, but there was nothing that English industrialists could do to increase this supply when it didn’t meet their needs. They had to economize on the labor pool that they had. This meant that increasing production required developing technological solutions to generate more output with the same labor input (i.e., the spinning jenny, the flying shuttle, and all the rest).
Slavery caused a problem on the demand side of the economy as well. Roman slaves could not legally own property. Though they were large in number, they were not a market in an economic sense. This meant that a third of the population of the empire was off the table to any theoretical industrial output. Industry in England didn’t face this issue. They had all of Britain and some of Europe to sell to.
Though the forgoing arguments make sense, it’s difficult to test them since we only have one example of industrialization in history. It happened in eighteenth century Britain and spread across the world from there. So it would seem that any attempt to generalize about why industrialization did not occur in other times and places would be impossible because of a lack of sufficient examples to use as test cases. Except there is another example: The United States in the nineteenth century.
In the 1700’s, the US was an agrarian country very much like Rome of the second century. Industrial methods came as an import from Britain and by 1800 textile mills began popping up. But they became concentrated in the Northeast. Though the industrial technologies were available to anyone with the inclination to take advantage of them, the Southern US never industrialized and remained completely agrarian long after the North completed industrialization.
The US South and North make an easier direct comparison than 2nd century Rome and 17th century Britain. The two regions of the US shared the same national government, the same access to ocean shipping, the same access to technology, and the same legal environment. Though there were differences like climate and population density, the biggest difference between North and South was slavery. It worked against industrialization in the American South in exactly the same ways it worked against industrialization in Rome.
Slaves were a third of the population in the antebellum South, very similar to estimates of the percentage in Ancient Rome. Slaves were primarily used for the cotton harvest, an activity that required a massive amount of manual labor, a requirement which was filled with a massive number of slaves. Apart from the harvest, the slave force had little to do. Southern slave owners attempted to hire out their slave labor during nonharvest times to anyone who would pay. This acted as an innovation killer throughout the South, since labor could be had at a cost lower than the marginal effort to deploy technological solutions.
Slavery in the South also worked against industrialization on the output side as well, just as in ancient Rome. Slaves could neither own nor buy property, so despite representing a third of the Southern population, they were nonexistent as a market. The South remained firmly agrarian right up until the Civil War, despite the North, which was right next door, industrializing at a furious pace during the same time period.
So there you have it. The reason there was no industrial revolution in the Roman Empire is slavery. And we know this because it’s the same reason that industrialization did not take hold in the American South 16 centuries later. I may revise this rant at some later time to clean it up and add citations.
TL;DR: Slavery - bad. Freedom - good.