“Do not remove a fence until you know why it was put up in the first place.”

The lesson of Chesterton’s Fence is what already exists likely serves purposes that are not immediately obvious.

Fences don’t appear by accident. They are built by people who planned them and had a reason to believe they would benefit someone. Before we take an ax to a fence, we must first understand the reason behind its existence.

The original reason might not have been a good one, and even if it was, things might have changed, but we need to be aware of it. Otherwise, we risk unleashing unintended consequences that spread like ripples on a pond, causing damage for years.

Elsewhere, in his essay collection Heretics, Chesterton makes a similar point, detailed here:

    Suppose that a great commotion arises in the street about something, let us say a lamp-post, which many influential persons desire to pull down. A grey-clad monk, who is the spirit of the Middle Ages, is approached upon the matter, and begins to say, in the arid manner of the Schoolmen, “Let us first of all consider, my brethren, the value of Light. If Light be in itself good—” At this point he is somewhat excusably knocked down. All the people make a rush for the lamp-post, the lamp-post is down in ten minutes, and they go about congratulating each other on their un-mediaeval practicality. But as things go on they do not work out so easily. Some people have pulled the lamp-post down because they wanted the electric light; some because they wanted old iron; some because they wanted darkness, because their deeds were evil. Some thought it not enough of a lamp-post, some too much; some acted because they wanted to smash municipal machinery; some because they wanted to smash something. And there is war in the night, no man knowing whom he strikes. So, gradually and inevitably, to-day, to-morrow, or the next day, there comes back the conviction that the monk was right after all, and that all depends on what is the philosophy of Light. Only what we might have discussed under the gas-lamp, we now must discuss in the dark.

As simple as Chesterton’s Fence is as a principle, it teaches us an important lesson.

Many of the problems we face in life occur when we intervene with systems without an awareness of what the consequences could be. While we are well-intentioned, it’s easy to do more harm than good. If a fence exists, there is likely a reason for it.

Chesterton challenged the common belief that previous generations were foolish. If we fail to respect their judgment and understand their reasoning, we risk creating new, unexpected problems. People rarely do things without a reason, and just because we don’t understand something doesn’t mean it’s pointless.

    Intellect is therefore a vital force in history, but it can also be a dissolvent and destructive power. Out of every hundred new ideas ninety-nine or more will probably be inferior to the traditional responses which they propose to replace. No one man, however brilliant or well-informed, can come in one lifetime to such fullness of understanding as to safely judge and dismiss the customs or institutions of his society, for these are the wisdom of generations after centuries of experiment in the laboratory of history. -- Will and Ariel Durant

Before I built a wall I’d ask to know
What I was walling in or walling out,
And to whom I was like to give offense.  --Robert Frost, Mending Wall