My Five Causes of the Decline and Fall of the Roman Empire

Rocochet asks this question over the weekend:  What are your top 5 causes of the fall of the Roman Empire.  OK, I will take a shot at this from my decidedly amateur perspective:

  1. Demographic collapse, caused by a series of plagues (perhaps even an Ur version of the black death) and possibly climate change (colder) that depopulated the western half of the empire
  2. A variety of policies (e.g. grain dole) that shifted population from productive farms to the cities.  In the 19th century, this shift was to be growth-inducing as farm labor was moving into growing factories, but no such productivity revolution existed in Roman cities.  The combination of #2 with #1 left huge swaths of farmland abandoned, and the Romans dependent on grain ships from North Africa to feed the unproductive mouths in large Italian cities.  It also gutted the traditional Roman military model, which depended strongly on these local farmers for the backbone of the army.
  3. The Romans lost their ability to be innovative in including new peoples in their Empire.  The Romans had a bewildering array of citizenship and tax statuses for different peoples who joined or were conquered by the empire.  For hundreds of years, this innovation was hugely successful.   But by the 4th and 5th centuries they seemed to have lost the trick.  The evidence for this is that they could have solved multiple problems -- the barbarians at the gates and the abandonment of farm land and the need for more soldiers -- by finding a way to settle barbarians on empty farm land.  This is in fact exactly what the barbarians wanted.  That is why I do not include the barbarian invasions as one of my five, because it did not have to be barbarian invasions, it could have been barbarian immigration.  Gibson's thesis was that Christianity killed the Roman Empire by making it "soft".  I don't buy that, but it may have been that substituting the Romans' earlier incredible tolerance for other religions in their Pagan period with a more intolerant version of Christianity contributed to this loss of flexibility.
  4. Hand in hand with #3, the Roman economy became sclerotic.  This was the legacy of Diocletian and Constantine, who restructured the empire to survive several centuries more but at the cost of at least an order of magnitude more state control in every aspect of society.  Diocletian's edict of maximum prices is the best known such regulation, but in fact he fixed most every family into their then-current trades and insisted the family perform the same economic functions in all future generations.  Essentially, it was Ayn Rand's directive 10-289 for the ancient world, and the only reason these laws were not more destructive is that the information and communication technologies of the time did not allow for very careful enforcement.
  5. Splits in the governance of the empire between west and east (again going back to Diocletian) reduced the ability to fund priorities on one side of the empire with resources from the other side.  More specifically, the wealthy eastern empire had always subsidized defense of the west, and that subsidy became much harder, and effectively ended, in the century after Diocletian.

I will add, as a reminder, that to some extent this is all a trick question, because the Roman Empire really did not totally fall until the capture of Constantinople in 1453.  So I should have stated at the outset that all of the above refers to the fall of the western empire in the late 5th century, which in part explains why #5 is there in the list.

And, if you were in a room of historians of this era, you could quickly get into an argument over whether the western Roman empire really fell in the late 5th century.  For example, the Visigothic Kingdom in the area of modern southern France and Spain retained a lot of Roman practices and law.  But I have gone with tradition here and dated the "fall" of the empire to 476 when the Roman Emperor was deposed and not replaced.


  1. Ron C.:

    Here's another perspective:

    "The energy system of the ancient Mediterranean civilisations was the same
    as that of all agrarian societies between the 5th millennium B.C. and the 19th century, and the level of per head consumption of energy was the same too. This system was based on food, firewood, and fodder for working animals. Despite the increase in useful knowledge and the extensive development of the agrarian energy basis, supported by a favourable climatic phase, this system was finally unable to support the increasing population. Per capita availability of energy began to diminish. An unfavourable climatic phase, from the 2nd century A.D., contributed to this decline."

  2. Ergo:

    The Romans lost their ability to be innovative in including new peoples in their Empire.

    That's certainly one way to spin grievously high amounts of unassimilable peoples, i.e. mass amounts of immigration. The fact is, every society has a ceiling for how much 'other' it can be force-fed over any given amount of time--the Romans discovered that after about 70-years of that, the jig was up.

    (Of course, you being an unapologetic, doctrinaire, libertarian, are constitutionally (cough) unable to state this blindingly simple fact as it relates to us in obvious, impossible-to-ignore (except for doctrinaire libertarians) ways.

    Further, the reason that Christianity killed Rome--or, at least, had a hand in it--is because Christianity has a soft underbelly of extreme *tolerance* baked into the cake that can be exploited by anyone willing to really push the envelope as, again, the modern West is a perfect example, with tolerance for obscene amounts of unassimilable immigrants being in the top five issues we face as a nation.

    Other than that, you make some good points (although the demo collapse was merely accelerated by the various plagues--Rome was doomed in the same way the modern West is doomed--they simply stopped having children because 'the good life' was far more attractive).

  3. Maximum Liberty:


    I've always bought #4 as one of the big ones, back when I was actually studying that exact topic. With the government attempting to gather as much of the Ricardian surplus as possible, trade shrank, limiting the size of the market. A smaller market means less specialization, which means lower productivity and -- maybe key -- lower incentive to innovate technologically. And really, what's the point of having a continent-spanning empire if all economic production is consumed locally?

    I'd also say that the public choice school would have a lot to say about rent capture from public positions. Tax farming was particularly horrific in the republic, but its incidence actually declines by later imperial times with the increasingly regulated economy.

    On your point #2, we shouldn't necessarily bemoan the Empire's inability to incorporate conquered peoples as it had in the past. The number 1 way it did so was by selling conquered populations into slavery.


  4. obloodyhell:

    }}} (Of course, you being an unapologetic, doctrinaire, libertarian, are constitutionally (cough) unable to state this blindingly simple fact as it relates to us in obvious, impossible-to-ignore (except for doctrinaire libertarians) ways.

    Yes, I've noted this about Warren myself.

    You may find this of interest:
    Immigration Explorer

    It's missing the 2010 census data, but it still quite useful. When some idiot -- and, on this topic, I include Warren, since he utterly ignores this every time I post it -- claims that **this** immigration is no different from previous immigrations, just show them this.

    1) Run the clock back to 1880.
    2) Change the pulldown to some country that has had significant immigration since 1880 (NOT Mexico at this point)
    3) Run the clock forward. Note that bubble size is PROPORTIONAL to population. This is per capita data, not strict numbers.
    Lather, rinse, repeat. Pick another group (still not Mexico) and do this again.
    Now, go ahead, and run it another time, THIS time picking Mexican immigration.

    Now go ahead and tell me that's not a significantly different immigration pattern from the others you looked at**. If you do, I'll call you an idiot to your face.
    ** and so: do you think the 2010 data is more or less than previous decades?

  5. Bram:

    #1-3 - The Empire had systematically destroyed the Roman Middle Class. They were taxed out of existence. The men who had been the backbone of the economy and the army were now living in slums on the dole. Replaced with slaves owned by un-taxed Patricians. Many in the artisan classes were selling themselves into slavery to escape crushing taxes - until the practice was outlawed, then they essentially became feudal serfs.

    Greed, sloth, slavery, and corruption had replaced enterprise, duty, and freedom.

  6. J Calvert:

    A more interesting and relevant question is why the Roman Republic fell and was replaced with Empire.

  7. Elam Bend:

    I can't recall where, but I've seen theories about the food production in N Africa dropping off for various reasons really screwing things up.

  8. Elam Bend:

    Disease is an underrated factor, but only because of other rot. Eastern Rome managed to pull through a couple of plagues that emptied 2/3rds of Constantinople because they were still robust.

  9. Elam Bend:

    The question should always be, why did Western Rome whither while Eastern Rome lasted until much later.

  10. Elam Bend:

    Also, Diocletian's edict came at a time of already great troubles and demographic decline. (though of course it made things worse).

  11. markm:

    Many of the problems Bram mentioned began in the Republic. In particular, much of the farmlands had come into the hands of a few wealthy Senators and huge masses were living in the slums on the dole after the Punic Wars, a century before the Republic fell. Look up the Gracchi brothers; their attempts to return land to small farmers got them murdered. (To be fair, they proposed to steal land from the rich under color of the law - but that's probably how most of the land had come into the possession of Senators in the first place.)

    Aside from economic participation, the Republic also depended on citizens participating in national affairs in three ways: voting, serving in office, and serving in the army (which was organized as a remarkably professional militia rather than a standing army). But in the period after the Punic wars, the Republic expanded rapidly into Iberia, North Africa, and Greece, and this participation suffered.

    The Republic never provided a way for Roman citizens to vote other than being physically in Rome on election day. Remember that with horseback & horsedrawn transport, even the Roman colonies in Italy were several wearing days away from the capital - so all the citizens in Roman colonies and outposts were effectively disenfranchised, unless they left their farms, businesses, or military border stations and went to live in Rome. Why should these people fight and die for Rome? The Empire didn't correct this, but it made the vote far less important.

    Furthermore, even in Rome itself, the urban poor, working class, and lower middle class were disenfranchised by the system of "tribes". In many of the elections each tribe had one vote. 2 million Romans were assigned to two "urban" tribes, while a few thousand wealthy and connected Romans were assigned to many tribes of about 100 each.

    Government offices: these were passed out by political processes in Rome. The disenfranchised had no chance there - usually not even for provincial offices in their own province, since the officials were elected or appointed in Rome.

    The Army: Part of the Republic's traditions was that the citizens provided their own arms when they went to war. This excluded the poor. It was changed eventually, but the change may have been even more damaging to the social cohesion of the Republic. During the Cimbri invasions of ~ 110-100 BC, coupled with problems in Numidia, Rome ran short of young men who could arm themselves, and also short of generals who hadn't disgracefully lost their armies. This created an opening for Marius, a wealthy provincial with a respectable military record, to become Consul in 107 BC - that is, governor and general. But he was posted to a war in Numidia and no army was provided. So he recruited the poor and armed them with weapons and armor collected from fallen legions. Rome now had much more manpower for war, but when the war was over you couldn't send these men back to the slums, and retiring them to farms in the provinces would not have worked well with men from the Roman slums. It was often easier to keep them in the army until they were too old to cause trouble - the militia was turning into a standing army.

    Marius won in Numidia, he defeated the Cimbri, and went on to be elected consul seven times - which was a gross violation of Republican customs. Romans had been appointed dictator before, but only for a limited time to handle a great emergency. Now there was precedent for a "Consul for life", which was barely less power than a dictator for life, and more power in reality when the office was joined to a permanent professional army.

    From there, the situation deteriorated into riots and plots in Rome, and then to a successful general returning from a far land and keeping his army together "to restore order", and then to rival generals fighting civil wars. Finally, the winner became Emperor - which if nothing else was an improvement in that there was only one of the bastards... Until the unwieldy size of the empire and the multiple attacks upon it came to require sub-emperors and co-emperors.