Chesterton's Fence

"Don't ever take a fence down until you know the reason it was put up." - G.K. Chesterton, The Thing (1929)

Overview

Chesterton's fence is the principle that if something exists, especially a rule, tradition, or structure, there is likely a reason for its existence, even if that reason is not immediately obvious, and that one should investigate and understand its function before deciding whether it ought to be altered or discarded.

The Thing (1929) is a collection of essays by G.K. Chesterton, the English writer and Christian apologist. In the essay "The Drift from Domesticity" he imagines a reformer who comes across a fence in a road and says, "I don't see the use of this; let us clear it away." A more experienced person replies:

"If you don't see the use of it, I certainly won't let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it."

Notes

Responsible reform requires understanding existing systems before altering them. The principle is a warning against uninformed or ideologically driven change, and it is cited in politics and law (gradualism rather than impulsive reform), in software engineering ("if you don't understand the code, don't delete it"), and by conservatives as a rationale for preserving institutions unless their removal is clearly justified.
It is not an Appeal to Tradition: the fence may still come down once its purpose is known and found wanting. The principle asks only that the purpose be known first. Most of my positions on institutions (UK Monarchy, Religious Education, Hard Secularism) are attempts to do exactly that: find out why the fence was put up, and then argue that the reason no longer holds.
The principle has a failure mode of its own: if "find out why" is allowed to take forever, it becomes a veto on all change, which is the appeal to tradition by another route. The answer to "why was this fence built?" is sometimes "nobody remembers", and at that point the reformer has done the work the principle asks for.

Also see

Appeal to Tradition
Appeal to Novelty
UK Monarchy
COVID-19 Origin, where the principle is invoked in reverse
G.K. Chesterton

Wikipedia: https://en.wikipedia.org/wiki/G._K._Chesterton#Chesterton's_fence

Linked from

Appeal to Novelty

Chesterton's Fence is the corrective on this side: before replacing the old thing, find out what it was doing.

Appeal to Tradition

It is not Chesterton's Fence. The fence asks why a tradition exists before removing it, and then permits its removal; the appeal to tradition treats its existence as the reason to keep it.

G.K. Chesterton

G. K. Chesterton (1874–1936), English writer, Catholic convert and apologist, author of Orthodoxy and the Father Brown stories. Witty and wrong about most things, but Chesterton's Fence is a genuinely useful rule.

COVID-19 Origin

Reason for rejection: Event 201 was a public tabletop exercise, one of many run over the preceding two decades precisely because a coronavirus pandemic was considered likely. Preparing for a predictable event is not evidence of causing it.…