For centuries, scholars have debated the causes of the rise and fall of empires.
The most widely held model holds that empires arise due to the unusually aggressive nature of their parent-societies which sweep over their more pacific neighbors. Such empires support themselves by large-scale pillaging which drives them ever to new wars. When they overextend themselves or run out of pillage to fuel their war engines, the empires collapse.
People evoke this model readily when seeking to criticize the war du jour of a Western nation. They always claim the nation acquired its wealth from a modern form of pillage, that it needs pillage to prosper but that the current conflict represents the fatal overextension that will bring its doom.
Yet does this model reflect the true causes that drive the life-cycle of empires, even on an abstract and simplified level?
I say no. I think empires arise when their parent-societies become significantly more internally egalitarian than their neighboring societies. This increased egalitarianism makes the nascent empire far more economically and militarily effective than its neighbors. The empire expands as long as it maintains its advantage in its degree of egalitarianism. When it loses that advantage, it lose its economic and military edge, it falls prey to neighbors who can now compete on an equal footing.
I should reinforce here that only relative, not absolute, egalitarianism counts. Comparing the egalitarianism of the empires of old to those found in contemporary (or worse, idealistic) societies doesn’t tell us anything. We can discern its significance only by comparing nascent and senescent empires to the societies immediately adjacent to them in time and space.
Why would egalitarianism alone significantly strengthen a society? I think an egalitarian society grows more militarily and economically “dense.” It marshals resources in a significantly more efficient manner, allowing it to overcome others, even if they have parity in population, technology and resources. I call this effect, “power density.”
Let’s look at two major military factors as examples:
First, egalitarianism enlarges the manpower pool. A more egalitarian society can mobilize a greater percentage of its population than can a less egalitarian society. The less egalitarian a society, the more it must worry about internal security. It must concentrate military ability in fewer hands. Most human societies throughout history could allow only a very small minority (usually < 10%) of their populations to possess real military capability. Letting military skills bleed out to the larger population led to rebellions. The more egalitarian a society, the less it must worry about giving effective military training to a larger percentage of the population. If two societies equal in all other factors save their levels of equality go to war, the more egalitarian society can field the larger, better trained army. Second, egalitarianism fosters merit promotion. The less a society cares about the origin of an individual and the more it cares about individual merit, the greater the likelihood that it will promote competent individuals to vital positions. If two equal armies meet, and one chooses commanders based on proven merit and the other based on station, the former usually wins. In the multi-battle campaigns that found empires, the merit-based military will easily dominate in the long run. Third, egalitarianism also makes it easier for a society to incorporate conquered peoples, so that its power density remains high even as it controls more and more territory. If we looked at an animated map showing in detail the evolution of political boundaries, running in fast forward mode, we would see thousands of small entities pushing constantly up against one another, some growing slightly larger and others slightly smaller but little overall change. This general stasis occurs because neighboring societies quickly reach a military equilibrium. They use the same technology, have the same social order, mobilize the same percentage of their populations etc. The continuous oscillations results almost entirely from chances factors that exert no persistent effect. Occasionally, however, a society will suddenly change its social order to something more egalitarian. Suddenly, it can field larger, more capable armies than before. It breaks the military equilibrium and its color on the map begins to spread. If a society succeeds in institutionalizing its new egalitarianism it rapidly evolves into a persistent empire that lasts centuries. If not, it fails within a generation or two. In either case, empires fall when they lose their egalitarian nature and not by overextension. No matter how successful or longstanding an empire, competitors remain. Giant empires find themselves surrounded by dozens of smaller societies, each one insignificant in itself, but collectively very significant. If an empire loses its power-density, it fights on even ground with each of its potential attackers. It loses as many fights as it wins at best. Eventually, with no distinct advantage, it gets chopped to pieces. The life-cycles of the Mongol and Roman empires demonstrate the role that gaining and losing the egalitarian edge plays. Genghis Khan welded the martially skilled but fractious Mongol tribes into history's most proficient military. Prior to Genghis, every individual lived in a deeply hierarchical society where birth dictated station. Even the clans themselves existed in hierarchies. Occasionally, a militarily successful Khan would collect an army of follower clans but those armies were poorly disciplined and tended to evaporate at the first major reverse. Genghis disrupted this system by ruthlessly promoting strictly based on merit. He even killed his best friend and oldest ally in a quarrel over the practice. Not only did this improve the quality of leadership but it secured ironclad loyalty from those whose new position in life depended entirely on the continued rule of Genghis. Later he treated non-Mongols, such a Chinese and Arabic engineers with the same evenhandedness. He conquered nearly twenty-five percent of Eurasia in his own life. Unfortunately, Genghis Khan broke his own rule when choosing his succession. He divided the empire among his sons and grandsons, many of whom could not handle the responsibility. The tradition of merit promotion disappeared and the Mongol Empire fractured and dissolved into the conquered cultures. The Roman Empire's life cycle divides neatly between the Republic and the Empire. The two labels apply not only to the form of government in each era but also the Empire's egalitarian, expansionist phase and its inegalitarian, declining phase. The Republic seems to have arisen when the monarchy lost a series of wars and the nobility turned to the plebes in desperation. The plebes demanded representation and the Republic followed rapidly. Just by looking at the map one might think that the Republic conquered far less than the Empire but, proportionally, the Republic went much further. Moreover, the Republic fought against peer societies, opponents with similar technology, knowledge and population density. The Empire, by contrast won its victories largely against primitive societies with much smaller population densities. It failed to make any headway against the Persians, who more evenly matched the Empire in terms of population density and technology. When the Republic devolved into the Empire, the Empire's power-density began its long slide. The Empire struggled to field armies one-half of the size of those of the Republic, even though it possessed a much larger population to draw on. Neither could the Empire match the training and motivation of the armies of the Republic. The armies of the Empire increasingly became composed of mercenaries with no willingness to fight the pitched battles in which the armies of the Republic regularly engaged. In the end, Roman armies could fight no better than their "barbarian" opponents. Indeed, the armies of the late empire were usually nothing but ad hoc assemblies of "barbarian" mercenaries. So does this model apply to modern empires as well? Certainly westerners subjugated the rest of the world due to their more egalitarian cultures, and they lost direct control when the subjugated peoples adopted more-egalitarian social and political structures and reduced the West's relative advantage. However, arguably the West still retains as much control over the non-western world, via indirect means, as the empires of old did with direct military force. Further, one could view the spread of western values and institutions across the world as a form of conquest by absorption. If two differing peoples grow tightly interlinked by common economic, political and social interest, how does that differ functionally from assimilation by conquest? However, internal asymmetries in power that produce an inegalitarian decision-making system still pose a threat to the "empires" of the West. The loss of Indochina in the '70s arose from the historically unprecedented concentration of media power that occurred at that time. Some have estimated that by the early-'70s fewer than 100 people determined what events the national media reported and what perspective they adopted on the events they did report. In effect, media power grew massively inegalitarian. The thousands of papers and publishers of earlier generations collapsed into 3 broadcast networks, a handful of major newspapers, a couple of wire services and a dozen major publishing houses. Most of the other decisions that made the '70s something of an economic and social trainwreck also resulted from this concentration of media power. Fortunately, the technological conditions that created the inegalitarian media did not last, media power decentralized and the country righted itself. So those who squawk that the war du jour represents our downfall operate from a fundamentally flawed model. America's radical egalitarianism, not its supposed greater aggressiveness, is what gives it its overarching dominance. As long as America remain a government and a culture of the people, it will never fall.