Chesterton's fence: the mental model, with an example

All models

Meenakshi has just started running her father's stationery shop in Jaipur. The shop has billing software now, but at the end of every sale her father still wrote a line in an old ledger notebook. It looks like double work, and she is ready to stop it.

Before she does, she asks one question: why was this started?

That is Chesterton's fence. The idea comes from the English writer G. K. Chesterton, in his 1929 book The Thing. If you find a fence across a road and cannot see why it is there, do not tear it down until you know why it was put up.

The decision, worked through

Meenakshi does not argue with the notebook. She asks her father, and then the two staff who have worked there longest. The answers are simple and a little surprising: during power cuts the software does not open, so the notebook is the only record of those sales. Her father also says it is how he spots when a regular customer's credit is running long.

Now she has a choice she did not have before. She could keep the notebook as it is. She could keep it only for power cuts. She could find a better way to track credit and then retire it. All three are fine. What changes is that she is deciding about something she understands.

It could also have gone the other way. If everyone had said "no idea, it was always done", and she could see no use for it, she could drop it, and she would do so knowing she had checked.

Where it goes wrong

The fence is not a reason to keep everything. Old does not mean useful, and asking "why" is not the same as being scared of change. Sometimes the reason turns out to be gone, and then you remove it with a clear mind.

It also does not mean waiting for a perfect answer. A few honest questions to the people who were there is enough. If nobody can say, you have still done the work.

One thing to try today

Think of one rule, habit or setup you are tempted to remove: a house rule, a step at work, a standing order. Before you change it, ask two people why it exists and write down what they say. Then decide whether to keep, change or remove it.

This is a way to think, not financial, medical or legal advice.

Each Sunday: one mental model and one real decision to try it on. Browse the model library.

What it is

Find out why it is there before you take it away.

The fence: A rule, habit or step that looks pointless to you today.
The question: Someone built it for a reason. Learn the reason first, then decide.

When to reach for it

When you are about to say 'this makes no sense, let's scrap it.'

A new job or a new role: A step in the process that nobody on the team can explain.
Taking over a family business: Habits your parents kept that you would not have chosen.
Rules at home: A house rule or a routine that was set long before you arrived.

An everyday example

An old ledger in a Jaipur stationery shop.

The urge: It looks like double work, so she is ready to stop it.
The better question: She asks her father and the longest-serving staff. The notebook covers power cuts and tracks a regular customer's credit.
What changes: Keep it, shrink it or replace it. Whichever she picks, she is deciding about something she understands.

The trap

Asking why is not the same as never changing anything.

Keeping everything: Old does not mean useful. Sometimes the reason is gone, and then you remove it with a clear mind.
Waiting for a perfect answer: A few honest questions to the people who were there is enough.

Try this today

One rule, two people and a pen.

Ask two people: Pick one rule or habit you want to remove, ask two people, write down what they say, then decide.