If you saw a fence in the middle of nowhere, and it didn't seem to be fencing anything in or out, would you feel OK about tearing it down?

I like Chesterton's Fence. I've seen how it can completely change somebody's thinking, even when they're angry, in one sentence. The answer to the fence question is obvious, and the link to the issue that they're railing against is clear. It seems like a sturdy and effective general principle of rationality.

Memeology

But how strong is this idea? It's worth discussing, and we might use it as a heuristic. But have we studied it? And if not, can we in good conscious recommend it to others? How do we know it's not just a powerful and potentially destructive intuition pump? How can we study a meme for its benefits and drawbacks? Is there a formal way to measure that evidence? When would we feel comfortable recommending a meme to a loved one when it might have harmful side-effects? How do we determine memetic benefit or harm in others?

Of course, we can test the meme out on ourselves or our friends. There, we have intuitions about what will sit well with their mind.

We can also try to anticipate a priori when the meme might turn destructive. It would be interesting to do some sort of an experiment on a meme. But it's easy to do the a priori examination.

How could Chesterton's Fence be harmful?

It could be used to bully someone into thinking that they have less knowledge about the thing in question than they really do. Or that they need perfect knowledge before tearing something down. Or that the thing in question is owned in a way that's akin to property rights, so that you feel not only that you need to know whether it’s a useful “fence,” but whether you have permission to tear it down.

Alternatively, it might divert their attention from an angry yet curious attitude - a frustration that might lead them to investigate the fence - to a calm and accepting, yet embarrassed and incurious attitude. "Oh yes, you're right, of course. There's probably a reason for this fence, no need to look into it any further." 

Chesterton's Fence could also provoke a false sense of confidence. Someone thinks for five seconds, comes up with an easy explanation for why the "fence" is there and a justification for why that doesn't matter, and now feels like they've got permission to destroy the "fence."

This meme could also become a way to shut off empathy or prop up an unjust policy or institution. You come across an apparently pointless barbed-wire fence in the middle of a beautiful valley. It mars the scenery horribly and you cut yourself climbing over it. Even if it's a necessary fence, did it have to be built in such an ugly way? Why not put a sign on it to explain why it's there and who to contact with any questions or complaints? Telling someone who complains about the apparent pointlessness of the fence misses that their real complaint is about its harmful side-effects, its ugliness, and the lack of accountability in its construction. It might even make them confused about why they complained.

Chesterton's Fence, at its best, converts a cavalier attitude into an attitude of curiosity and investigation. A more ambiguous outcome is when it soothes a moment of frustration and leads to a lack of concern about the "fence." A bad outcome is when it kills somebody's sense of care and curiosity and investigative energy.

Given that it has potentially bad outcomes, merely seeing that Chesterton's Fence has changed somebody's mind isn't automatically a sign that they've become more rational, or that the meme was beneficial.

Guideline

Chesterton's Fence is probably most useful to provoke curiosity and restrain the powerful from thoughtless destruction. It might help an activist accept small but sensible hindrances to focus on building a compelling case against the real problems they face. But if it makes people even more arrogant after being provoked, or is used to humiliate people into accepting an unjust or simply bad situation because they had an illegible first impulse that the fence seemed pointless, then the Chesterton's Fence meme would be harmful.

When you encounter the Chesterton's Fence meme in the wild, I suggest that you think CuSHA (Curiosity, Study, Haughtiness, Acceptance) to diagnose which of these reactions it’s generating.

Conclusion

Overall, Chesterton's Fence needs context. That means it's not a fully general principle. It's a piece of wisdom, and it's not any more "rational" than any of the thousands of other pieces of common sense that we have in our minds. It might be under-appreciated, but that's another contextual judgment call.

If we wanted to convey rationalism to a broader audience, my guess is that doing presentations on catchy memes like Chesterton's Fence is the wrong way to go.

I do think it's possible that showing people how memes can have good, ambiguous, or bad outcomes, and instilling an appreciation of context and audience, might be a safer and more general-purpose lesson.