For those not familiar with Dr. Joseph Tainter, he is an Anthropologist and US Historian that wrote in 1988 the book: "The Collapse of Complex Societies."
The best way I can describe this approach to viewing the history of empires and complex societies is one of systems dynamics. A complex society has multiple systems functioning within it. Such systems include financial, agricultural, energy reliance, military, social welfare, infrastructure, etc...
These systems, in the beginning, as they are being created give society a rather high rate of return. As they are developed, their use is optimized and society benefits from this. But over time, a hyper-complexity develops. Manageability of these systems through regulations, protection, growth, and overall maintenance becomes complex as well. And after a point, the costs of maintaining these systems become extractive. The costs exceed the benefits. A diminishing rate of return is reached.
We have seen this with America's military costs in maintaining world order. We have seen this with our financial system that to grow, needs to become more speculative, and thus, more extractive of the productive economy. We have also seen this with the amount of debt the US economy needs in order to grow GDP. Our bang for each buck borrowed, so to speak, is diminishing... yet the costs of debt, the interest, grows.
We have also seen this in energy. To extract oil, or to develop "green energy" we need to expend more and more existing energy. The rate of energy return too, diminishes.
So what does this mean when a hypercomplex society, or industrial civilization, reaches a point of diminishing growth and growing costs? Tainter calls the result of such a process "collapse." In another presentation, Joseph Tainter defines this collapse:
"Collapse is the rapid simplification of society."
Think about that. What is simplification? It's the system telling us that it can't grow at the current rate... that it wants to regress to a more stable, simpler phase. The Wall Street meltdown of 2008 is such an example. The system was telling us that it can no longer handle the creation of ever-increasingly risky loans, despite credit default swap (insurance) protection. The system was telling us that leverage, debt in other words, was no longer productive for the economy. It became unbearable. The system wanted to shake this debt off.
One could also argue that the US may have reached a point where it no longer benefits as much from influencing the Middle East... that is, the benefits it derives are no longer greater than the costs. Just look at Iraq, Afghanistan, at Egypt... What was spent, and what was gained. When the US first entered the Middle East after WWII, it benefited tremendously. Now that it has to share the gains with other countries such as China, the benefit is not as great.
Economics aside, maybe we should also view the world as a complex system that requires various types of inputs to produce a certain amount of outputs. And then maybe, the solutions we arrive at are more realistic.
Below is a brief video of Joseph Tainter describing the process of collapse. Now keep in mind, I'm not saying we're entering a stone age. It's a process of simplification, which means to me that it takes place over certain period of time. Things change slowly, sometimes quickly. One generation doesn't live as well as the previous generation. Growth slows. New monetary systems develop to handle this new emerging paradigm. There will be destabilizing periods as well, maybe even wars. There will likely be political and societal upheaval.
Actually, one could say that all of the above is taking place right now. That it has been taking place the past ten years.
But keep in mind, eventually, things do stabilize.