What Makes a System Tick?

To truly understand sustainability challenges, or any complex challenge, you need more than awareness of interconnections. You need insight into what makes a system function. Why do some systems remain stable over time while others spiral out of control? In this lesson, we’ll unpack several foundational concepts that explain how systems work from the inside out.

Steady States and Dynamic Balance

Let’s begin with a natural example: a pond.

Imagine a small pond fed by rainwater and sunlight, teeming with plants, fish, and microscopic organisms. While activity is constant–plants grow, animals feed, nutrients circulate–the system can remain relatively stable over time. This is known as a steady state: a condition where inflows and outflows are balanced, enabling the system to persist despite continual change.

Pond ecosystems illustrate a central principle in systems thinking: stability doesn’t mean stagnation. A system can be in motion and still remain in equilibrium.

Reflection prompt: Can you think of a team, business unit, or process in your organization that feels stable, even though change is constantly occurring? What keeps it in balance?

Stocks and Flows: The Building Blocks of System Dynamics

To maintain a steady state, a system must manage its stocks and flows.

  • Stocks are the accumulations in a system, like the water in a pond, the money in a savings account, or the number of trained staff in an organization.
  • Flows are the rates of change to those stocks, like rainfall and evaporation, deposits and withdrawals, or hiring and turnover.

The timing and rate of these flows can determine whether a system thrives or collapses. For example, if fish in the pond are caught faster than they can reproduce, the stock (fish population) will decline, even if the inflow (births) continues.

Understanding stocks and flows gives you the power to anticipate system behavior over time, not just observe it in the moment.

System Boundaries: Where Do You Draw the Line?

Every system is defined by a boundary: an invisible line that separates what’s inside the system from what’s outside. But here’s the catch: boundaries are not fixed. They are subjective and strategic.

If you’re analyzing supply chain emissions, do you stop at your company’s direct activities, or do you include upstream suppliers and downstream users? The answer shapes not just your data but your strategy.

Setting system boundaries requires thoughtful framing. Too narrow, and you miss critical influences. Too broad, and the complexity may become unmanageable.

Question for thought: How do the boundaries you set in your own work affect the solutions you prioritize?

Governance: Who Gets a Say?

Human-based systems aren’t just technical. They’re political and social. Governance refers to who has the power to shape a system’s rules, flows, and feedbacks.

In a pond, no one governs explicitly, but in human systems, decision-makers matter. Who allocates resources? Who designs feedback mechanisms? Whose perspectives are included or excluded?

For sustainability, governance plays a pivotal role. Consider water management in a drought-prone region. Decisions made by a regulatory board, local farmers, or multinational corporations can dramatically shift the system’s resilience and fairness.

But governance isn’t just about individual leaders. It’s often embedded in units and organizations. Cities, school boards, corporate departments, and multilateral agencies all make resource allocation decisions based on their own rules, goals, and priorities. A city council may prioritize green infrastructure; a procurement team may choose suppliers aligned with ESG goals. Each of these acts as a governing node within larger systems.

This reminds us that influence can be distributed. Governance may rest with formal authorities, but it can also be exercised through networks, partnerships, or even algorithmic systems that prioritize certain data or outcomes over others. Understanding where these centers of control reside, and how they interact. can reveal unexpected leverage points for change.

Power, voice, and participation can be the most overlooked yet impactful elements in a system’s design.

The Role of Visual Tools and Analogies

A classic visual showing how inflows and outflows impact accumulation over time.

Bathtub with faucet and drain. Faucet represents inputs/flow into the system. The water in tub represents the stock. The water flowing out of the drain represents the outflow.

Diagrams showing how producers (like algae), consumers (like fish), and decomposers (like bacteria) interact within a closed-loop of nutrient cycling and energy flow.

Such tools are not just for scientists or engineers. They can be powerful ways for teams and stakeholders to align around a shared understanding of system behavior and interventions.

Question for thought: What is one system in your life, personal or professional, that might look different if you applied one or more of these principles?

Closing Thoughts

Systems thinking isn’t just about connecting the dots. It’s about understanding why those dots behave the way they do. By learning to see steady states, manage stocks and flows, set boundaries intentionally, and surface governance dynamics, you gain the tools to shape systems and not just react to them.