What is periodization and why must we be aware of it when discussing the 4 Versions of Systems Thinking?
The 4 Versions of Systems Thinking (also referred to as "waves") are a useful conceptual, historical, and pedagogical tool, but beware of periodization errors.
Beware of Periodization
Wikipedia details the dangers of periodization well:
"Periodization is the process or study of categorizing the past into discrete, quantified named blocks of time in order to facilitate the study and analysis of history. This results in descriptive abstractions that provide convenient terms for periods of time with relatively stable characteristics. However, determining the precise beginning and ending to any "period" is often arbitrary.
To the extent that history is continuous and ungeneralizable, all systems of periodization are more or less arbitrary. Yet without named periods, however clumsy or imprecise, past time would be nothing more than scattered events without a framework to help us understand them. Nations, cultures, families, and even individuals, each with their different remembered histories, are constantly engaged in imposing overlapping, often unsystematized, schemes of temporal periodization; periodizing labels are continually challenged and redefined, but once established, a period "brand" is so convenient that many are very hard to shake off." (Wikipedia)
Whether we use the metaphor of waves of versions, both are forms of periodization. We should remember that their purpose is primarily pedagogical—to aid understanding.
Along these lines, there are numerous ambiguities in placing any specific manifestation of system thinking. For example, I was recently asked where:
"awareness based systems change from Peter Senge/Academy for Systems Change fits in?"
My answer is that several version of systems thinking influenced this work:
Senge was highly influenced by Jay Forrester and SD so Senge's original work is in wave 1. "Awareness" is a subconcept of metacognition which starts in the 2nd order cybernetics of wave 2. So, I would say it would be straddling wave 1 and 2.
The 4 Systems Thinking Versions are not an an exact science, it's a metaphor, but it's a useful one if we are weary of the negative effects and bias of periodization.