Chesterton's Fence

Mental architecture from the other side.

There is a particular kind of man who, upon walking through a field and finding a fence in his way, decides that the fence must be removed.

He has examined the fence. He has determined that it serves no apparent purpose. There are no cattle on either side of it. The land it divides looks identical in both directions. The wood is weathered, the posts are leaning, and nothing in the surrounding landscape suggests why the fence should be standing where it stands. He is a reasonable man. He proposes its removal on the obvious grounds that he can see no reason for its presence.

Against this man, G. K. Chesterton offered a wise rebuttal. “Go away and think,” he said, “and when you can come back and tell me why the fence was put here, then I may permit you to take it down.”

Chesterton wrote this in 1929, in an essay called The Thing, during a period when the modern impulse to remake institutions was reaching one of its periodic peaks. He was not defending fences as such. He was making a point about the asymmetry of knowledge between the man who built the fence and the man who proposes to remove it. The builder had a reason. The reason may no longer apply, or it may apply with even greater force than it did originally - but the reason existed. Until the would-be reformer has reconstructed that reason in his own mind, he is not in a position to judge whether the fence is obsolete or essential. He is merely a man with an opinion about a structure whose purpose he has not understood.

Chesterton was writing about social institutions - marriage, inheritance, religious practice, and the small disciplines of ordinary life. He was responding to a generation that had grown impatient with arrangements it could not immediately justify and that proposed to dismantle them in the name of progress. The principle has worn well. It applies almost wherever men encounter rules they did not write and feel the urge to set them aside.

It applies, perhaps nowhere more usefully, to the investor.

Every serious investor accumulates, over time, a set of personal disciplines. They are private. They are rarely written down. They emerge from experience, from observation, and from specific mistakes whose particulars have been forgotten but whose lessons have hardened into rules. The investor does not buy beyond a certain position size. He does not chase a stock that has already moved. He keeps a certain reserve in cash. He refuses to invest in businesses he cannot understand within a fixed period of study. He sells when a thesis breaks, even if the price has not yet confirmed the break. He does not borrow to invest. He waits.

These are his fences. Each one stands in a field he has walked across many times. Each one was built, originally, in response to a specific event he can no longer fully recall - a position that turned against him, a thesis that fell apart, or a moment of false confidence that cost him real money. The fences accumulated quietly over the years, until they came to define the perimeter of his discipline.

And then comes the bull market.

In every cycle of euphoria, the investor stands in his field and notices, for the first time in years, that his fences are inconvenient. The position-size limit prevents him from concentrating into the stock that is doubling every quarter. The cash reserve sits there earning nothing while everything else compounds. The refusal to chase keeps him out of the moves his peers are bragging about. The discipline of waiting feels indistinguishable, in this moment, from cowardice. The fences appear obsolete. The field looks identical on both sides of them.

This is the moment the Chestertonian question must be asked.

Why was that fence put there?

Not “why might it be useful in theory?”. Not “what does the textbook say about position sizing?” . The personal question. Why did I, specifically, build this fence? What was the event, or the series of events, that convinced me to put a post in this exact piece of ground? The answer is almost always specific. It is almost always remembered, on closer inspection, more vividly than the investor expected. The position that he sized at fifteen percent of his portfolio in 2008 and that nearly destroyed his career. The thesis he held too long because he could not bear to be wrong in public. The loan he took against his portfolio in 2007 that taught him, with appropriate violence, why one does not borrow to invest. The fences are not arbitrary. They are built on open wounds.

The reformer in the field of an investor’s own discipline is, almost always, a younger, hungrier, more confident version of himself who has forgotten what the older version learned. This younger self looks at the bull market, sees the fences as constraints, and proposes their removal in the name of seeking returns. He is a reasonable man. He has examined the fence. He can see no purpose for it in the current landscape.

He has not gone away to think.

The cost of removing fences without remembering why they were built is one of the most reliable patterns in the history of capital. The leverage taken on at the moment leverage felt unobjectionable. The concentration that broke past the position-size limit at exactly the moment the position was about to be punished. The cash reserve deployed at the worst possible moment because holding cash had begun to feel like an indulgence. The discipline of patience abandoned in the final months of a mania, just before the patience would have been vindicated. Each of these is a man walking into his own field, finding a fence he no longer remembers the reason for, and taking it down on a sunny afternoon.

The Chestertonian discipline, applied to one’s own investing practice, is this: before any rule you have lived by for years is set aside, the rule must be reconstructed. Not just the rule itself - the reasoning behind it. The investor must be able to articulate, in detail, what the rule was designed to prevent and why he came to believe that prevention was necessary. If he can do this and still believe the rule should be set aside, he has earned the right to set it aside. He has gone away. He has thought.

If he cannot reconstruct the reasoning - if the fence simply looks unnecessary because the field around it currently looks calm - he has identified, with perfect precision, the moment at which the fence is most necessary. A discipline whose purpose one has forgotten is a discipline one is about to violate. The forgetting is itself the warning. The forgetting is the conditions in which the original error was made re-emerging in a new costume.

There is a deeper observation lurking here, which Chesterton himself understood. The reformer believes he is in a stronger epistemic position than the builder because he has the benefit of hindsight. He can see how the field has evolved since the fence was built. He has more information. He is, by his own reckoning, better placed to judge.

This is almost always wrong. The builder was responding to events that had actually occurred. The reformer is responding to events that have not yet occurred. The builder had seen the cattle that strayed, the children that fell, the boundary disputes that erupted. The reformer sees an empty field on a calm day and concludes that the fence is purposeless. He is reasoning from the absence of evidence in his own time, while the evidence that built the fence sits buried in someone else’s memory - possibly his own, from a younger and wiser life.

The investor who keeps his fences in place is not being timid. He is being epistemically humble. He is acknowledging that the version of himself who built the fence had information the current version does not have direct access to. The fence is a message from his past self to his future self, written in the form of a rule. To dismantle the message without first decoding it is to assume that the past self was foolish - an assumption the future self will, with great regularity, come to regret.

Walk through the field. Notice the fences. They are older than your current mood, and they were built by someone who knew something you have temporarily forgotten.

Find out why each one stands before you propose to remove it. Most of them, on inspection, were placed there at considerable cost. The cost was paid so that the fence could be built. The fence was built so that the cost would not have to be paid again.

Leave them where they are.

Stay still.

Win slow.

Theodore