Gall’s Law: Complex systems can work, but there’s a catch

There is a line by John Gall, a pediatrician who wrote about systems theory, that has aged better than most management literature:

"A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be made to work. You have to start over, beginning with a working simple system."

Gall is not saying that complex systems are hard to design, or that they tend to have bugs. He is saying that a complex system conceived whole, in advance, does not work and cannot be repaired into working. The only complex systems that function are the ones that were once simple systems that functioned and evolved from there.

A working simple system carries within it a great deal of information that never appears on the blueprint: the failures it already survived, the exception cases it metabolized, the adjustments made in real time when reality refused to follow even the best laid plans. Complexity designed from scratch has none of this. It is built on assumptions, and assumptions are the mother of all... if you've seen the movie, you know. Each interaction between its constituents is a wager that has never been settled. Multiply enough unsettled wagers together and the system becomes a machine waiting for the right wrench to be thrown at its gears.

When Ecotierra's founders built Urapi, they did not begin with the full architecture. The model as it stands today, infrastructure that makes loans viable, loans that regenerate the land, land that yields carbon, commercialization that also de-risks the loans by allowing the collateral to reach the market, and projects that sustain the infrastructure, looks intricate when drawn as a whole. Investors sometimes call it complex. But it was never designed complex. Each layer was laid only once the one beneath it had held. The infrastructure had to prove itself before the lending made sense. The lending had to function before the regenerative cycle could be trusted to compound. Had they attempted to engineer the entire loop in advance, on paper, they would have produced something elegant and inert, an architecture that had survived nothing.

This is where Gall's Law must be read carefully, because it is easily misread. It is not an argument against planning, nor a licence to tinker aimlessly and hope structure emerges. Ambition is permitted. Complexity is permitted. What is not permitted is complexity that has not yet paid for itself. The constraint Gall imposes is not on how complex a system may eventually become, but on the order in which that complexity is allowed to compound. Each layer must survive contact with reality before the next is laid upon it. Complexity, in other words, must be earned.

It is perhaps no accident that this observation came from a doctor. The human body is one of the most complex working systems we know of, and also the clearest vindication of Gall's Law. No one designed it whole. It is a vast assembly of smaller systems, each comprehensible on its own, each kept not because it was optimal but because it survived: every organ, every pathway, every regulatory loop is the residue of millions of years of versions that failed and were discarded. The body is not elegant in the way a blueprint is elegant. It is emergent: redundant and full of tolerated errors and workarounds left in place because they held. That’s why it works, precisely because none of its complexity was integrated in advance. All of it was earned over millions of years.

The heuristic is therefore simple:
Before adding a layer of complexity to a system, ask what load the current layer has already borne. If the answer is none, the complexity is unearned, and you are no longer growing a system, you are designing one from scratch, and beginning to accumulate the fragility Gall implicitly warned about.

In other words, complexity must be earned before it can be trusted.