Dear Abram,

The system collapse theory of Bronze Age Collapse is nuanced, complex, sophisticated and most likely wrong.

As a general rule, historians love explanations that emphasize 'complexity' and 'nuance'. Be very wary of these explanations. They sound great as a verbal explanation but they are highly flexible hypotheses that are difficult to falsify and can easily explain any amount of data. The perfect fit for verbal bullshitters - which probably accurately describes the vast majority of non-quantitative social theorists -like historians.

A little experience with dynamical systems will show how problematic these models are. Be wary anytime somebody is talking about 'multicausal' explanations. There are typically two regimes: something is made out of many many independent factors, giving Gaussian distributions or there is one or two dominant eigenfactors that explain the vast majority of the variance. I could say more about this. 

The most likely explanation for Bronze Age collapse is changes in warfare: elite corps of chariot archers losing out to javelin -throwing massed infantry consisting of a melange of experienced mercenaries. Earlier infantry-based tactics were ineffective against the sophisticated hit-and-run tactics of corps of chariot archers but eventually new tactics were devised - like using javileneers to hit the horses and wheels of chariots. 

 Writing and much of the archeological finds of this period rely on a demand for luxury- trade and elite scribes. Once the chariot-archer elites disappeared so did their luxury trade and elite scribes; hence a 'collapse'. 

Much more can be found in Drews' excellent book "The End of the Bronze Age: Changes in Warfare and the Catastrophe ca. 1200 B.C."

Your argument has a Holocene, sedentary, urban flavor, but I think it applies just as well to Pleistocene, nomadic cultures; I think of it as an argument about population size and 'cognitive capital' as such, not only about infrastructure or even technology. Although my confidence is tempered by mutually compatible explanations and taphonomic bias, my current models of behavioral modernity and Neanderthal extinction essentially rely on a demographic argument like the one made here. I don't think this comment would be as compelling without a reminder that almost everyone explains these phenomena via interspecies differences in individual cognitive adaptation, as opposed to demography.

On behavioral modernity, I am a gradualist; I do not think there was a sudden pulse of innovation. Signs of modernity, like a wider resource base, public symbol use, and certain technologies appear and then disappear, before becoming a permanent fixture later in the record. The most striking example of this would be ancient Australia, where humans did not reliably demonstrate all features of behavioral modernity for the first 25,000 years of residence even though these features were present in contemporaneous cultures in different geographic locations; Australia also happens to be one of the last places to which humans migrated. The idea here is that reduced population size, and thus density, affects the fidelity and bandwidth of social learning in lots of ways (e.g. decreased redundancy and specialization), resulting in a less sophisticated behavioral repertoire, as well as reduced selection for public symbol use (since there are no frequently encountered outgroups to which to signal).

On Neanderthal extinction, I think this is a collapse in the sense of your post, by a failure to reliably transmit cognitive capital. The life history of hominins is similar to a case of growth-dependent economics, where large energy and time investments are made under the expectation of future economic productivity. While I think environmental effects started the decay, temperate specialists as the Neanderthals were, I think they went extinct ultimately because these effects started a process that gradually invalidated the preconditions for reliable cultural transmission in that species.

In the videogame "Starcraft", it's economics (macro) that wins wars. A player can win every single battle (micro) and still lose the game, if the other player's economy is improving their relative position faster than they are losing militarily. A common tactic is to make small attacks on the other player's economy production units, attempting to do a lot of economic damage without fighting any military units. The true scope of the damage might not be obvious, since the "fog of war" conceals most of what the other player is doing. I remember one game where I thought I was doing quite well, despite several early attacks damaging my economy, and then suddenly a giant army just marched through my base destroying everything. Not good. It seems that for a city to be prosperous it needs to have an economy capable of producing a powerful military force, then actually use that economy to produce a powerful military force. It's probably not a healthy way to live, but sometimes when I look out at a city I think back to my Starcraft days. When I feel good about the city, I imagine unit production buildings and dug-in artillery as far as the eye can see. When I feel bad about the city, I imagine Zerglings and fire. This is probably not a healthy way to live, but it does focus the mind.

Thinking back, I had some friends who told me that I should focus more on doing what I enjoyed, and focus less on doing the right thing. In retrospect, those were bad friends who wanted to justify their own lack of vision.

"The Last Psychiatrist" (blog) explains that it's easier to reform society than to reform oneself, and people often look to fix the society around them instead of looking to fix themselves. The apocalypse to avoid is not of society collapsing, but of the individual collapsing: of failing to obtain a house and have children, or whatever most represents individual collapse.

The point that’s relevant for us is the infrastructure Ponzi scheme: how cities usually can’t presently afford to maintain the infrastructure they build, instead relying on future growth to pay for it.

Ive seeen is pushback against that. Apparently the claim as not that suburbs aren't supporting, but things look different when you include business districts.

It becomes amazing that we make progress at all, when you think of it this way: it's often to the state's advantage to keep the population ignorant and poor.

States are also in competition with each other. A state with more military innovations can invade you. A state with more advanced culture can assimilate you. Your population can defect and move to a state that offers them a better deal.

It occurs to me that from a system robustness perspective, luxury is actually great, because it implies surplus capacity (assuming society can and will divert luxury-production to essentials-production in a crisis).