Systems theory
Central to the history of design patterns was a drive to tame the complexity inherent in architecture, both in terms of physical construction and software. Both forms of development deal with sequences of constructive actions with continuously interacting elements. Interactions between elements, which in turn create emergent behaviour, are what systems theory is all about. So, given how linked together they are, why do we fail to teach systems theory alongside design patterns?
We can use systems theory to analyse questions regarding the larger systems at play in the design pattern space, not only in terms of the patterns themselves but also the development of the theory of patterns. Moreover, we can examine the systemic problems caused by the current processes for finding, publishing and their eventual use. There were certain forces at play that drove the adoption of patterns, yet others have diverted them toward a different form. The pattern movement changed over time, and systems theory helps to explain and predict some of the otherwise unexpected outcomes.
In later works by Christopher Alexander1, it becomes apparent that systems of feedback between larger social entities—such as the pattern movement, the software development industry, and the construction industry—led to some far-reaching consequences. These outcomes range from the mundane, including mass selling-out, to the unnerving reality of corruption, bribery, and death threats. Systems theory will help us to frame these events so that we can see them coming before they arrive and avoid similar problems in the future.