These are some takeaways from reading “Thinking in Systems” by Donella H. Meadows. I'm mainly focusing on trying to get a basic grasp of how to think about complex systems. So mostly high level definitions and notes so far, with room to learn and dig into more later

---

Notes

System - “A system is an interconnected set of elements that is coherently organized in a way that achieves something.”

Elements are usually the easiest parts of a system for us to see and understand. They’re typically physical things; in a tree they would be the leaves, roots, branches and trunk. They can be complex systems of their own - it’s usually helpful to represent them simply with the goal of modelling how they contribute to the system

Interconnections hold everything together and allow elements to transfer something between each other and communicate. “Something” can mean: energy, information, physical traits, physical elements. In the tree example there’s the internal signals that the tree uses to communicate, flows of nutrients and flow of energy / matter.

The Function or Purpose of a system is only possible due to the combination of elements and structure of interconnections. This seems strongly linked to the "outer system" that a particular system is a part of. In the example, changing the purpose of a sports team to lose instead of win likely mean the overall game or network has changed significantly

Stocks are elements that represents the result of flows within the system. They can act as delays, buffers or shock absorbers, otherwise thought of as to decoupling inflows and outflows.

Feedback loops are chains of connections from a stock through a series of changes and back to the stock. They can only affect future behaviour (nothing is instant)

• Balancing loops seek stability, provide resistance to change and restrain growth
• Reinforcing loops are self enhancing and lead to exponential growth or runaway collapse

Constraints are always present and can occur due to stock or flow limitations

Behaviour results from structure, and reveals itself as a series of events over time. Systems with similar structures (stocks + flows + feedback loops) have similar behaviour

Complex Behaviour can occur in a system in the form of oscillations, shifting dominance or delay changes. It often arises as the strength or delay of feedback loops change. Small changes in one variable can cause complex changes or runoffs in the system (non-stability)

Surprises are common when dealing with complex systems.

• They’re full of nonlinear or exponential behaviours
• System boundaries are arbitrary - there is rarely a true “separate” system
• Long feedback loops can be difficult to forecast
• Individual elements can produce surprising results given they represent complex sub-systems and may not have access to the full context of the system

Resilience and Evolution can be an outcome of self organizing elements in a system. Paths to increased resilience include: learn, create new structure, diversify, complexity

Change is constant in systems.

• Elements that change the most are least likely to impact the overall function of a system (leaf on a tree, student through a university).
• As long as the slow-changing elements and interconnections remain, they system is less likely to change. Even changing a key element or leader in a cemented structure is less likely to introduce change
• Changing the structure of interconnections is very likely to affect the purpose and overall function of the system.