Gall’s Law
Gall’s Law shows that a working complex system is something you grow, not something you draft.
What Is It?
Gall’s Law states that a complex system that works is invariably found to have evolved from a simple system that worked, and that a complex system designed from scratch never works and cannot be made to work by patching it. You have to start over with a working simple system.
John Gall, an American pediatrician with a side interest in systems theory, introduced the idea in his 1975 book Systemantics: How Systems Work and Especially How They Fail, drawing on patterns he’d noticed across both medicine and large-scale computer systems.
Why Does It Matter?
Organizations run into this whenever a large transformation, platform, or process redesign is planned and built all at once, in full, before anyone uses it. The ambition of the design usually isn’t the problem. The absence of a working intermediate version is. A simple version that runs, even imperfectly, generates the real feedback a complex system needs to evolve correctly. A complex system built in isolation has never been tested against reality at any point along the way.
This is why pilots, phased rollouts, and minimum viable versions of a change tend to outperform comprehensive redesigns launched all at once, not because ambition is bad, but because a working simple version is the only path that has ever reliably produced a working complex one.
What Changes Once You See It?
You stop treating a big-bang launch of a fully-built system as the safer, more thorough option.
You start asking whether there’s a simpler version of this that could be running and generating feedback right now, instead of waiting for the complete version.
You start treating early, ugly, working versions as more valuable than polished, comprehensive, untested ones.
Common Misunderstandings
- It is not an argument against ambition or long-term vision. It’s an argument about sequencing: build the simple working version first, then let complexity accrue on top of it.
- It doesn’t mean any simple system will eventually become a working complex one. The simple system has to actually work, not just be simple.
- It is not the same as saying complexity is bad. Gall’s Law assumes complex systems are often necessary. It’s a claim about how they come into being, not whether they should exist.
- It doesn’t guarantee success just because you started small. A simple system that works can still be evolved badly from there.
Diagnostic Question
Is there a simpler version of this that already works, or are we building the complex version first and hoping it works?
Explore Further
Field Notes
None yet.
Origin
John Gall introduced the law in Systemantics: How Systems Work and Especially How They Fail (1975), later republished and expanded as The Systems Bible.