If systems change over time, the change may follow a linear or cyclical pattern.
For people who would prefer to listen to a description and critical evaluation on cyclical patterns, a recent lecture is “Thoughts on Cyclical History & Generations” | Prof. CJ | May 22, 2017 | The Dangerous History Podcast (episode 0140, 1h53m) is at http://profcj.org/ep140/ . This covers:
- Ancient conceptions of cyclical time
- The concept of linear time
- Some modern conceptions of cyclical time
- The generational theory of William Strauss & Neil Howe, authors of (among other things) the famous book The Fourth Turning: An American Prophecy
- What the Strauss-Howe theory says about recent American history as well as about its present & future
- CJ’s thoughts on Strauss & Howe’s theory
For a human system, the cycle has been described as a saeculum with a periodicity of about 80 years, with four turnings (analogous to spring, summer, autumn, winter) of about 20 years each. This research is explained online at The LifeCourse Method, published circa 2012. The generational theory is more thoroughly explained by William Strauss and Neil Howe | The Fourth Turning | Broadway Books | 1997, (which has a preview on Google Books, as well as on Amazon). There is a Wikipedia page on Strauss-Howe generational theory, as well as a continuing discussion at generational-theory.com .
This theory is based on Anglo-American history dating back to the 1400s, and admits that other societies could be on different cycles. While William Strauss passed away in 2007, Neil Howe is still active with his research, and even posts at https://twitter.com/howegeneration. A search on “Neil Howe, turnings” rapidly turns up more interviews and recently published articles.