Mistakes #4: breaking Chesterton’s fence in the presence of bull

(Mistakes #1, #2, #3)

Lots of prominent activities don’t immediately make pragmatic sense. I mean, they make sense in the sense that you want to do them, but not in the sense that you can give an explicit account of why you want to do them.

For instance, visiting family in holidays. For one thing, why do we even have holidays? For a few days, and not on other days? And why eat turkeys or champagne then, and not eat them the rest of the time? For another thing, why do we have families? And why see your family exactly that week? For those who like their families, is that the most convenient week? Or do people really need to coordinate in holding family dinner at the same time as people not in their families? For those who don’t like their families, why go to so much trouble to see people whose only special feature is that you were already forced to spend too much time with them decades ago? Also, why guess what someone else wants you to buy for them, while they spend the same amount on a guess for you? And why does everything have to be decorated in colors and sparklinesses that nobody during more sober times finds aesthetically pleasing?

As a young person, learning about the world, you can respond to this sort of thing in at least two ways. One option is to go along with the things. Perhaps you have great trust in society. Perhaps you don’t notice. Perhaps you have little curiosity or passion for improving the world. Perhaps you have heard of Chesterton’s fence.

Another option is to politely disregard any of the things that don’t make apparent sense, and redesign your life according to reason. Or rudely disregard any of the things that don’t make sense, if you don’t see the use in politeness! If you see no reason for eating dinner before dessert, or exchanging gifts, or doing well in school, then you just don’t do those things.

I have a soft spot for the social innovator, who sees the people needlessly toiling for senseless or forgotten goals and is willing to face social censure to make a better world. However I think young, intelligent people often make mistakes this way. It’s not clear to me that these mistakes can be avoided without giving up a valuable attitude, but my guess is that some can.

There are at least three closely related mistakes: breaking down Chesterton’s fence because you don’t know why it’s there; breaking down Chesterton’s fence because the owner doesn’t know why it is there; and breaking down Chesterton’s fence because the owner thinks it is there for reasons you know to be nonsense.

Chesterton’s fence

Chesterton’s fence is from a famous principle, which basically says ‘don’t take down fences unless you know why they were put up’. Or relatedly, don’t try to reform society while you don’t understand the reasons for its present behaviors. Most fences are put up not by crazy people, but by people who had some sensical motive. Even if you can’t see a bull, the fact that there is a fence there is suggestive.

Suppose you don’t understand why people go out for coffee instead of caramels. And suppose that you have an important date to organize which is likely to succeed if you don’t mess it up. One thing you might say is, ‘well, people go out for coffee a LOT, but I don’t see why coffee is especially good for dates, and caramels are cheaper and more delicious’. Then you might opt for the caramel date. This would be knocking down Chesterton’s fence.

When younger, I didn’t intellectually understand why people would shave their legs, or maintain their garden, or try at sports at school, or listen to their feelings if they weren’t obviously well-aligned, or get a job, or keep in much touch with their family once they had left home, or live in a building, or drink alcohol. So I either didn’t do these things, or assumed I would not later on, and so did not prepare for them. Even though I knew they were popular activities among humans. They aren’t obviously good activities, even now, but the point is that I didn’t really consider whether people have them for a reason that I didn’t understand. I quickly disregarded them because I didn’t understand them. And in fact I think I was often wrong to think they were worthless.

The basic mistake with Chesterton’s fence is either not taking the existence of a thing as evidence that someone has a reason for it, or inferring too little from that about whether it is good on your values.

Chesterton’s fence after contacting the caretaker

A more subtle mistake involves inquiring after people’s reasons for the inexplicable fences they protect, finding that can report none, then hastily trashing the fences. For instance, you ask your mother why it is important for you to have table manners, and she says ‘it just is’, so you stop doing it.

The problem with this is that people do lots of relatively useful things without having much explicit understanding of what they are doing or why. People pick most behaviors up from other people.

Sometimes someone once understood why the behavior was good, and intentionally constructed it for others to use. Like CBT or the Alexander Technique. Sometimes the thing wasn’t spread because someone understood it, but still it was experimentally checked, at least informally. Like drinking lemon and honey when you are sick, or making eye contact the right amount. Other times perhaps nobody ever understood or had the opportunity to check well for efficacy, but still social forces preferentially select for things that work, at least to some extent, for some goals. Arguably like religion, or being idealistic as a young person, or following your curiosity.

Even if never in history had anyone ever explicitly understood why table manners were important, their prevalence is decent evidence that you shouldn’t immediately abandon them.

Chesterton’s fence with a stupid sign

After realizing this potential mistake, there is another mistake you can make however. That is where you ask people the reason for a thing, and they give you a reason, and it’s a bad one—and then you’re allowed to break down the fence, right? If you know it was put there by some crazy person to keep the flying pigs at bay?

For instance, suppose you ask your math teacher why math is important, and she says that as an adult you will need to be able to add and subtract numbers when you are shopping or if you have a job in administration or science. And you know that people can have calculators, so adding skills are not really important. And you don’t care much about grocery price comparisons anyway, since your value of time is too high. And basically none of what you are doing is adding or subtracting anyway! It’s all trigonometry and calculus. Then you might reasonably infer that math is of no use to you. If this person who appears to be very invested in math—whose whole life is about encouraging you to do math—can’t come up with anything better than that, then surely you are safe to ignore math. (Loosely based on a true story).

The problem here is that often instead of doing reasonable things while being clueless about why (as discussed in the last section), people come up with reasons for the things they are doing, which are unrelated to the process that caused them to be doing the thing.

Perhaps the builder of the fence did it because something scares his dogs when they go up the hill. Whatever it is, he doesn’t want it coming down to his house. He has a correct intuition that a fence there would make him feel safer. He comes up with a story that the problem is flying pigs, which are fortunately respectful of fences. This is pretty much irrelevant. In this case the fence does indicate something you should watch out for.

The math teacher is teaching math because other forces recognized the value of math, recognized that she was good at both high school math and at teaching, and paid her enough to teach it. She doesn’t know about the details of how this came about, or why it was considered a good idea. However sometimes students ask her why they should do math. She ponders this, and reasonably thinks about when math comes up in her own life. She comes up with calculating things. She might also think of ‘being a math teacher’—an equally thrilling inducement to the ambitious student. Though the math teacher is in charge of the fence, she doesn’t automatically know why it is there. It feels like she should, which may compel her to search for reasons, but the reasons have had somewhere between seconds and hours of thought applied to them, while the behavior itself underwent a more thorough optimization process.


This makes things hard, because when are you allowed to just write off things as not valuable? If someone looks you straight in the eye and says ‘I’m clashing these pots together because aliens’, do you have to reserve substantial credence that they are doing it for a good reason?

I think the main point is that in these cases you need to have actual beliefs about what is going on, and decide based on the apparent situation. You don’t get to just blanket disregard things because you don’t understand them, because its proponents don’t understand them, or because its proponents claim to do them for bad reasons. But you can update somewhat toward thinking the things are useless, and perhaps a lot.

An important part of figuring out when you should disregard inexplicable behaviors is understanding where the behavior came from. If your pot-clashing friend feels compelled to clash pots because it makes him feel less anxious about the aliens, then probably it is worth it for him, for entirely non-alien reasons. There is even some chance that it would also be useful in relieving your own anxieties about other things. If your friend clashes pots because he read online that this is the anti-alien-club sanctioned way to fend off aliens, then there are fewer models on which clashing pots is advantageous for either of you.

Sometimes understanding where behaviors come from will tell you that a behavior is well-honed, but not for goals you have, so this understanding allows you to break down fences you might have otherwise respected. For instance, if you are a teetotaler, and your best guess is that the excitement about festival X is closely related to its cheap and delicious booze, then you can infer that the festival is an unusually poor fit for you, even if nobody can explain well to you why they love it.


In general, I propose acting like a person who takes seriously the possibility that there is a bull in the paddock, rather than someone who is obliged to do a checking ritual before they are allowed to gleefully smash down the fence. Then follow the usual epistemological procedures for determining what statements are true and what actions are good.

13 responses to “Mistakes #4: breaking Chesterton’s fence in the presence of bull

  1. Some heuristics for when you should break down Chesterton’s fence:

    -When the process hasn’t actually had much optimization power behind it. Related to “why do math?”, I knew one college where they added discrete math as a requirement for the math major primarily in order to attract a certain professor to the school. This did not convince me to take discrete math.

    -When there’s a specific mistake in the process that was used to make the decision. For example, Citibank thought that a certain project would cost ~$3,000,000 to create. But it turned out that the requirements for the project had been drafted by someone who was not at all an expert in the technology, and that there was a substantially easier way to do it–I completed the project singlehandedly in 2 weeks.

    -When the original reason made sense at one point, but there has been a significant change in circumstances that’s strong enough to account for the difference. Many video-based startups would not have been successful when most people had 56k internet, but are now able to succeed because people have fast internet.

    -When replacing the fence is quite cheap. For example, there might be a piece of code that seems redundant which you could delete and test. If your code then fails the tests, you can easily restore the deleted piece (provided you have some sort of version control.)

  2. For example, Citibank thought that a certain project would cost ~$3,000,000 to create. But it turned out that the requirements for the project had been drafted by someone who was not at all an expert in the technology, and that there was a substantially easier way to do it–I completed the project singlehandedly in 2 weeks.

    Why, oh why? Tell them you can do it on a budget of $750,000 and 6 months, subcontract it out, and take a vacation.

    • Alas, I wasn’t that savvy back then–I would take a much different approach today (e.g. not working for Citibank as an employee.)

    • Thinking that you know the original reason that the fence was there (as Katja illustrated with the school math example) is a very large failure mode I see among rationalists (and other people too, granted). Much harder to know with social and legal conventions than with tech conventions.

  3. Chesterton’s Fence is an imperfect metaphor, I feel. Fences are not social mores. Individuals do not sit down and decide “Hey, let’s all hate gay people.” is going to be a social more; this is something that comes out of the emergent properties of a society. And those properties tend to hone in on values that you may not necessarily share.

    Plus, fences are physical objects. They’re easy to break and hard to build. You can trial the ignoring of a social more pretty easily, by identifying areas in which you think you’ve explored the space of possible problems, ignoring the fence, and carefully observing the results, then just going back to following the social more if you find out that ignoring it doesn’t seem to help.

    I do agree about the checking ritual, however; a lot of people will hone in on the weakest example of evidence being offered if they want to prove that a custom or habit is useless or obselete. If you see an old fence, you should consider that someone put it up, and if you see a custom, you should consider that it hasn’t died out or been replaced with another, and so you should consider looking if you can’t see a reason for either from where you’re standing right now…but I see a lot of useless, unconsidered behavior in both individuals and soceity, and I can think of a lot of times in my own life where being underconfident in the math and overconfident in what everyone else was doing steered me wrong.

  4. My experience has been that believing in Chesterton’s Fence has been enormously costly, on average, compared to not believing in it.

    Otoh, blending in, not trying to contribute much, being empathic and respectful, and not always scaring the timid has been very useful, and has accomplished those things that Chesterton’s Fence is endorsed as accomplishing.

  5. Tearing down fences is hard work, too. In my experience, people do not tear down fences because they do not see a reason why the fence is there, but because it is the way of a different, more important building (often a fence built in a different direction). Sometimes we see a conflicting, but less important reason, but mostly we just believe the original reason to be evil.

    The situations that you are describing often do not amount to tearing down a well-respected fence, but simply jumping it, because you don’t see a reason to make a detour (whereas neurotypicals might have less tendency to question the wisdom of their peers). Demolishing a social fence requires rallying a crowd, and we may have to come up with some compelling normative argument (the fence is evil!) to do that.

    For instance, prescribed monogamy intends to suppress sexuality, to make people easier to control. Laws against the use of psychedelics are meant to cement the dominant trip of consumerism. The concepts of sin and virtue are designed to lure people into religious institutions that maintain a monopoly on redemption. Taxes are a way of the lazy, parasitic majority to steal the fruits of the toils of the smart und hard-working. Gender specific marketing intends to perpetuate systematic oppression of women. Wester democracy is a circus to distract the public from those that are in charge, and act against their interest. The primary purpose of copyright law is the defense of incumbent industries against newcomers.

    Our judgements may be wrong, of course. Fortunately, there are often examples of social experiments where other people have torn down the same fence, and we get to observe the outcomes. (We rarely seem to do that, because it is much more rewarding to cherry pick or fudge examples to confirm our current normative preferences.)

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