There is an inter­est­ing paper called How Com­plex Sys­tems Fail. It’s a col­lec­tion of 18 related obser­va­tions about com­plex sys­tems and about when and how they fail. The obser­va­tions are as follows:

1. Complex systems are intrinsically hazardous systems.
2. Complex systems are heavily and successfully defended against failure.
3. Catastrophe requires multiple failures – single point failures are not enough.
4. Complex systems contain changing mixtures of failures latent within them.
5. Complex systems run in degraded mode.
6. Catastrophe is always just around the corner.
7. Post - accident attribution accident to a ‘root cause’ is fundamentally wrong.
8. Hindsight biases post - accident assessments of human performance.
9. Human operators have dual roles: as producers & as defenders against failure.
10. All practitioner actions are gambles.
11. Actions at the sharp end resolve all ambiguity.
12. Human practitioners are the adaptable element of complex systems.
13. Human expertise in complex systems is constantly changing.
14. Change introduces new forms of failure.
15. Views of ‘cause’ limit the effectiveness of defenses against future events.
16. Safety is a characteristic of systems and not of their components.
17. People continuously create safety.
18. Failure free operations require experience with failure.

It’s worth read­ing the paper in it’s entirety but the gist of the paper is that attempts to ana­lyze fail­ures in com­plex sys­tems are often them­selves doomed to fail­ure because of false assump­tions about the nature of these sys­tems. The main point is that because com­plex sys­tems are inher­ently redun­dant, attempts to reduce col­lapse to a sin­gle point of fail­ure are incor­rect. In fact mul­ti­ple fail­ures have to occur simul­ta­ne­ously for the sys­tem to fail com­pletely and fur­ther­more, com­plex sys­tems tend to con­tain mul­ti­ple fail­ures at any one time any­way. It’s the con­flu­ence of just the right com­bi­na­tion of fail­ures that causes the entire sys­tem to col­lapse.

Ulti­mate­ly, a holis­tic approach must be taken to the health of the sys­tem.

Inter­est­ing­ly, com­plex sys­tems in the sense meant by this paper tend to be sys­tems with human com­po­nents. Hos­pi­tals, stock mar­kets, firms, and met­ros would be exam­ples of com­plex sys­tems. It’s not men­tioned in the paper, but I sus­pect that if these human insti­tu­tions con­sti­tute com­plex sys­tems, would­n’t big­ger human insti­tu­tions such as gov­ern­ments and entire civ­i­liza­tions con­sti­tute the same? If so, and I think this is the case, then this analy­sis would apply to these big­ger things as well. Attempt­ing to fig­ure the cause of the col­lapse of civ­i­liza­tions such as the Roman Empire or the Maya would run into the same road­blocks as ana­ly­i­sis of those other sorts of sys­tems. You would not be able to pin­point the cause of col­lapse to any one fac­tor or rea­son.

Per­haps the most famous his­tory book of all time is Gib­bon’s The Decline and Fall of the Roman Empire. This is a long and com­pre­hen­sive account of Rome from its sup­posed peak in the sec­ond cen­tury to the final col­lapse of the Byzan­tine Empire. One of the most inter­est­ing things about this book is that Gib­bon attempts to for­ward a the­sis about why the empire ulti­mately col­lapsed. He believes that the decline of civic and mar­tial virtue over time, has­tened by the rise of Chris­tian­i­ty, lead to Rome’s even­tual inabil­ity to defend itself from the Bar­bar­ian invaders, which is a quite straight­for­ward expla­na­tion.

How­ever if the com­plex sys­tems the­ory of civ­i­liza­tions is true, it would sug­gest that Gib­bon’s expla­na­tion for the fall of Rome is far too sim­ple and that many other fac­tors likely con­tribut­ed. And in fact, it looks like that might be the case. Many his­to­ri­ans have taken Gib­bon’s account to task and his expla­na­tion is no longer very pop­u­lar, but the num­ber of expla­na­tions prof­fered in its place are numer­ous. In fact, there are at least 210 given rea­sons for the Fall of Rome, and this kind of fig­ures. Why should there be a sim­ple, straight­for­ward expla­na­tion? Rome as a civ­i­liza­tion trans­formed itself almost entirely mul­ti­ple times of the course of mil­len­nia, yet con­tin­ued to run up until the very end. When one strength would dis­ap­pear it would com­pen­sate with anoth­er. It would take a long series of dis­as­ters to finally destroy the empire.

Like­wise, when peo­ple talk of lost civ­i­liza­tions such as the Maya or the Indus Val­ley Civ­i­liza­tion, and won­der what hap­pened to the them, per­haps there isn’t a sim­ple sat­is­fy­ing answer such as ‘war’ or ‘famine’ or ‘a decline in civic virtue’. Per­haps the real answers is the much less sat­is­fy­ing ‘many things ulti­mately came together over hun­dreds of years to force the col­lapse of the civ­i­liza­tion’ and per­haps the attempt to draw a sim­ple les­son from these col­lapsed civ­i­liza­tions is an exer­cise in van­i­ty? When a con­flu­ence of many fac­tors leads to such a dra­matic col­lapse it’s easy to pick out the ones we want and to use them to con­struct an easy moral which con­forms to our pre­con­ceived notions. And so maybe the thing we learn about when we study civ­i­liza­tional col­lapses is really our­selves.