Path dependence
Path dependence is when the outcomes available today are constrained by the sequence of decisions and events that came before — history matters, and early choices can lock in long after the reasons for them have vanished. Where you can go depends on where you’ve been.
How it works
When analysing why something is the way it is, trace its history rather than assuming it’s the optimal current design. Early, sometimes accidental choices get entrenched by switching costs and network effects, locking in outcomes that no one would choose from scratch.
How to use it
- Explaining why suboptimal standards (QWERTY, imperial units) persist despite better alternatives.
- Understanding that current options are constrained by past commitments, not just present logic.
- Recognising that early decisions cast long shadows — choose foundational ones carefully.
Worked example
The QWERTY keyboard was designed to slow typists and prevent jamming on 1870s typewriters. The jamming problem vanished long ago, but everyone learned QWERTY, so everyone keeps using it — a suboptimal layout locked in purely by history.
Where it fails
Path dependence can be overstated — sometimes the persisting choice is actually fine, and "it’s just lock-in" wrongly assumes a better alternative exists and would win if not for history. Lock-in is real, but not every legacy is a trap.
The deeper point
It is why "why is it like this?" so often has a historical, not a logical, answer. The most entrenched features of any system — standards, institutions, habits — are frequently frozen accidents, optimal for a world that no longer exists.
Frequently asked
- What is path dependence?
- It’s when present outcomes are constrained by the sequence of past decisions and events — early, sometimes accidental choices get locked in and shape what’s possible long after the original reasons disappear.
- What is an example of path dependence?
- The QWERTY keyboard: designed to prevent jamming on old typewriters, it persists despite better layouts simply because everyone already learned it. History, not current merit, keeps it dominant.
- Why does path dependence matter?
- Because current arrangements aren’t necessarily optimal — they’re the product of history, switching costs, and network effects. It also means early, foundational choices cast long shadows and deserve extra care.
Related
Editorial synthesis © ReadGlobe 2026, drawing on the mental-models tradition (Charlie Munger, Farnam Street) and the primary sources for each model. · Last reviewed 2026-05-29.