Gall’s law
Gall’s law holds that a complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch rarely works and cannot just be patched into working.
How does Gall’s law work?
Working complexity is grown, not authored. You ship the smallest thing that genuinely works, let reality stress it, and add structure only where the working system demands it — so every added part is load-bearing rather than imagined.
A complex system that works has invariably evolved from a simple system that worked.
How do you use Gall’s law?
- Starting a product or platform: ship a deliberately small version that works end-to-end before layering on features.
- Re-architecting: evolve a working system in steps rather than rewriting it wholesale into a big-bang replacement.
- Process design: grow an organisation’s rules from practices that already worked, not from a master plan drawn in the abstract.
What does Gall’s law look like in practice?
The web grew from a simple, working system — plain HTML over HTTP — and accreted complexity (CSS, JavaScript, APIs) on top. Grand “designed-from-scratch” rival systems that tried to specify the whole stack up front mostly failed to launch or never worked at scale.
Where does Gall’s law fail?
It is not a licence to never plan or to ship sloppily — the starting system must actually WORK, not merely be small. And some domains (a bridge, a payment ledger) need heavy up-front design where “evolve it live” is reckless.
- It is descriptive in hindsight and gives no forward recipe for which simple seed to plant among many that could work.
- Evolving a system live can lock in early choices that become expensive to reverse once the system grows around them.
- Its patience can lose a market to a competitor whose larger up-front bet captures users before your simple system matures.
The counter-model: Path dependence — Evolved systems accumulate path-dependent constraints from their early form, tempering Gall's optimism that starting simple is always safest.
How do you apply Gall’s law, step by step?
- Define the smallest version of the system that genuinely works on its own.
- Ship that working core rather than a scaled-down sketch of the full design.
- Grow it by adding one proven capability at a time.
- Watch for early choices hardening into constraints and revisit them before they lock in.
- Reserve heavy up-front design only for domains where getting it wrong is catastrophic.
Frequently asked
- What is Gall’s law?
- The observation that complex systems that work evolved from simpler systems that worked — and that complex systems designed from scratch tend not to work.
- Where does Gall’s law come from?
- From John Gall’s 1975 book Systemantics (later General Systemantics), a satirical-but-serious study of how systems fail.
- How is Gall’s law used in software?
- It is the case for MVPs and incremental delivery: ship a small working system and grow it, rather than designing a large complex system up front.
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ReadGlobe. (2026). Gall’s law. https://readglobe.com/model/galls-law/
"Gall’s law." ReadGlobe, 30 June 2026, readglobe.com/model/galls-law/.
Primary source: Wikipedia
Editorial synthesis © ReadGlobe 2026, drawing on the mental-models tradition (Charlie Munger, Farnam Street) and the primary sources for each model. · Last reviewed 2026-06-30.