Why Nations Fail: The Origins of Power, Prosperity, and Poverty

Commodus, who was more like Caligula or Nero than his father.
    The rising instability was evident from the layout and location of towns and cities in the empire. By the third century AD every sizeable city in the empire had a defensive wall. In many cases monuments were plundered for stone, which was used in fortifications. In Gaul before the Romans had arrived in 125 BC , it was usual to build settlements on hilltops, since these were more easily defended. With the initial arrival of Rome, settlements moved down to the plains. In the third century, this trend was reversed.
    Along with mounting political instability came changes in society that moved economic institutions toward greater extraction. Though citizenship was expanded to the extent that by AD 212 nearly all the inhabitants of the empire were citizens, this change went along with changes in status between citizens. Any sense that there might have been of equality before the law deteriorated. For example, by the reign of Hadrian ( AD 117 to 138), there were clear differences in the types of laws applied to different categories of Roman citizen. Just as important, the role of citizens was completely different from how it had been in the days of the Roman Republic, when they were able to exercise some power over political and economic decisions through the assemblies in Rome.
    Slavery remained a constant throughout Rome, though there is some controversy over whether the fraction of slaves in the population actually declined over the centuries. Equally important, as the empire developed, more and more agricultural workers were reduced to semi-servile status and tied to the land. The status of these servile
“coloni”
is extensively discussed in legal documents such as the
Codex Theodosianus
and
Codex Justinianus
, and probably originated duringthe reign of Diocletian ( AD 284 to 305). The rights of landlords over the
coloni
were progressively increased. The emperor Constantine in 332 allowed landlords to chain a
colonus
whom they suspected was trying to escape, and from AD 365,
coloni
were not allowed to sell their own property without their landlord’s permission.
    Just as we can use shipwrecks and the Greenland ice cores to track the economic expansion of Rome during earlier periods, we can use them also to trace its decline. By AD 500 the peak of 180 ships was reduced to 20. As Rome declined, Mediterranean trade collapsed, and some scholars have even argued that it did not return to its Roman height until the nineteenth century. The Greenland ice tells a similar story. The Romans used silver for coins, and lead had many uses, including for pipes and tableware. After peaking in the first century AD , the deposits of lead, silver, and copper in the ice cores declined.
    The experience of economic growth during the Roman Republic was impressive, as were other examples of growth under extractive institutions, such as the Soviet Union. But that growth was limited and was not sustained, even when it is taken into account that it occurred under partially inclusive institutions. Growth was based on relatively high agricultural productivity, significant tribute from the provinces, and long-distance trade, but it was not underpinned by technological progress or creative destruction. The Romans inherited some basic technologies, iron tools and weapons, literacy, plow agriculture, and building techniques. Early on in the Republic, they created others: cement masonry, pumps, and the water wheel. But thereafter, technology was stagnant throughout the period of the Roman Empire. In shipping, for instance, there was little change in ship design or rigging, and the Romans never developed the stern rudder, instead steering ships with oars. Water wheels spread very slowly, so that water power never revolutionized the Roman economy. Even such great achievements as aqueducts and city sewers used existing technology, though the Romans perfected it. There could be some economic growth without innovation, relying on existing technology, but it was growth without creative destruction. And it did not last. As property rights became more insecure and the economic rights of citizens followedthe decline of their political rights, economic growth likewise declined.
    A remarkable thing about new technologies in the Roman period is that their creation and spread seem to have been driven by the state. This is good news, until the government decides that it is not interested in