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.

Gall’s law

Systems & design

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 it works

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.

How to use it

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.

Worked example

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 it fails

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.

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.

Systems thinking Emergence Antifragility First-principles thinking Wikipedia: John Gall (author)

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.