Evolved vs. Designed Rules

Definition

Simple rules arise through two fundamentally different processes. Evolved rules emerge without anyone designing them — through natural selection over generations, or through a community's repeated interactions converging on a shared norm — and they gain legitimacy and fit precisely because they weren't imposed. But because no one authored them, evolved rules tend to be implicit and deeply entrenched, making them hard to examine critically or abandon when circumstances change. Designed rules, by contrast, are deliberately formulated by a person or group, drawing on personal experience, borrowed experience (advice, books, analogies), scientific evidence, or negotiation among stakeholders with conflicting aims — and because someone can point to why the rule exists, it can also be revised.

In the Book

Chapter 4 opens with butterfly "hilltopping": male and female Melitaea trivia butterflies use four evolved rules ("fly uphill most of the time," "fly toward the highest slope in sight," "pause at local peaks but leave quickly if unsuccessful," "periodically make a random movement") to find mates across sparse, unpredictable terrain — rules refined over roughly 150 million years of random variation and selection, with unsuccessful variants going extinct. The book draws the parallel to Friedrich Hayek's account of how human customs like "stick to one side of the road" emerged from repeated real-world conflicts without any designer. Standup comedy's "don't steal jokes" norm gets the same treatment: for most of the twentieth century joke theft was unremarkable (Milton Berle was notorious for it), but the norm shifted as comedy moved from generic material and delivery toward personal, distinctive routines, and the norm now includes specific, community-enforced sub-rules — the person who originates a joke's premise owns it over whoever delivers the punch line, and the first comedian to perform a joke on television owns it against a rival claimant. Against this, the chapter identifies four ways people deliberately design rules: reflecting on their own experience, borrowing others' experience through advice or analogy, distilling scientific evidence, and negotiating among stakeholders with divergent views — the approaches developed in later chapters through Tina Fey and other examples.

Why It Matters

This distinction matters whenever you encounter a rule, convention, or "the way we've always done it" and have to decide whether to trust it or interrogate it. An evolved rule's durability is itself weak evidence of fitness — it survived because it worked, on average, under past conditions — but that same lack of an author makes it resistant to conscious revision even after conditions change, since no one owns the decision to update it. Recognizing whether a rule in front of you was evolved or designed tells you both how much implicit validation it carries and how much resistance you'll meet trying to change it.