For elegant analogies, think in systems

Did someone forward you this? Click here to subscribe.

As an apple matures, it produces a gas called ethylene. That initial puff triggers more gas, hastening the fruit’s ripening. The gas permeates its environment, where other fruits inhale it. They start to ripen as well.

In childbirth, contractions bump the infant’s head against the cervix, stimulating the release of oxytocin. This hormone amplifies the contractions, which trigger more oxytocin. The contractions increase in strength and frequency until delivery.

These events are everyday examples of reinforcing feedback loops: a resource (ethylene, oxytocin) stimulating its own release. Each loop is part of a system: interconnected parts organized around a goal. And thinking about systems? Well, that’s called systems thinking.

What is it actually, though?

At its core, systems thinking means focusing on the whole rather than breaking things down into parts. We talked about abstraction in the last issue; systems thinking is a form of abstracting that allows us to carry lessons from engineering into biology, from biology into materials science, and so on.

Understanding system dynamics opens up some interesting possibilities for communication. First, we need to define a few terms.

All systems comprise stocks and flows. Stocks are quantities that build up over time: money in your bank account, water in a reservoir. They can be renewable, meaning they are replenished at a particular rate, or nonrenewable, meaning they’re available all at once.  

Anything that travels through a system is a flow: your paycheck, water in a stream. The most common flow in any system is information: the S&P 500, executive orders, memos, votes, enrollment numbers. All flows involve delays, and the extent to which information flow is delayed can help or hinder a system’s ability to self-regulate.

Most systems are shaped by feedback loops, which come in two flavors. Reinforcing feedback loops are characterized by exponential growth and collapse. Neither fruit ripening nor childbirth can be sustained for long; both processes intensify and burn out quickly.

On the other hand, balancing feedback loops are marked by stability and resistance to change. They bring a system back to homeostasis: think of a thermostat kicking on to maintain room temperature or a pancreas releasing insulin to regulate blood sugar. 

Most systems have multiple stocks, flows, delays, and loops. As the relative strengths of feedback loops change, complex behaviors emerge.

Systems thinking for analogy

If systems thinking gives us a common language for comparing different systems, then we can use system dynamics to draw connections for our audience through analogy. 

For example, customer complaints and physical pain are both information flows that push a system to adapt.

The impacts of greenhouse gases and cigarettes both involve delayed feedback. Behavior can be difficult to modify when consequences feel far away.

My twin toddlers’ escalating spats sometimes feel like a runaway nuclear fusion reaction leading up to a supernova. In reality, both are reinforcing feedback loops.

Mentally clarifying system dynamics can help us recognize and construct metaphors that make foreign or complex topics more relatable.

How to apply it

Analogies consist of a target (what we’re trying to describe) and a source (a familiar point of reference).

Start with your target. Locate the stocks, flows, delays, and loops in your system. What dynamics do you see?

In the toddler example, an argument over a toy might cause the children to grow progressively more agitated until one lashes out.

Next, choose your source. Consider your audience carefully. What’s a familiar reference point that follows similar dynamics? 

In the supernova example, the accumulation of matter by a star remnant leads to a runaway carbon fusion reaction. This uncontrolled reaction rapidly increases temperature and pressure until the star becomes unstable and explodes.

Of course, your audience may not relate easily to supernovas. Banks, restaurants, families, and cars are but a few examples of familiar systems people encounter every day.

Analogies can be extended, mixed, stretched beyond their breaking point. They can aid in understanding, but they can also limit understanding if taken literally.

Maybe analogies themselves are little systems: the target and the source contain everything we know about each concept, and their perceived similarities flow between them, heightening our perceptions of certain details and collapsing when they stretch too far.

More on this topic:

• Thinking in Systems: A Primer by Donella H. Meadows

• Joshua Rothman on how we know when a system has failed in The New Yorker

• Claudia López Lloreda on crafting analogies in The Open Notebook

• Bec Roldan on using systems thinking to teach chemistry and environmental disasters in Chemical & Engineering News

• Take a stab at modeling systems with Stella Online or Kumu

Hi! I’m Alex. I write about scientific research for nonprofits, universities, and brands. I also help experts communicate their own research. Learn more about my work or connect with me on LinkedIn.

Are you struggling to explain a particular concept? Hit reply–I’d love to help.

Enjoying this newsletter? Share it with a friend.

Correction: This newsletter originally misidentified the gas responsible for fruit ripening. It is ethylene, not ethylene oxide. Caught that one myself ;-)