Path dependence
Sometimes the reason something is the way it is, is that it used to be the way it was.
The standard example is the QWERTY keyboard. It was designed in the 1870s to prevent typewriter keys from jamming. The technical reason no longer exists (no keys, no jam), but every keyboard in the world is still QWERTY because billions of people learned QWERTY and the cost of switching is enormous.
Path dependence is the principle that the order in which things happened matters. Two industries can start from identical conditions and end up in completely different places based on tiny early decisions.
This shows up in obvious places (software stacks, urban layouts, industry standards) and in many places people don't notice.
Examples:
- A startup picks a database in 2015 because it's trendy. Ten years later they're still using it because migrating would be a 2-year project even though there are better options now.
- A company hires its first VP of Sales in 2010 because a friend was between jobs. The team that VP builds defines the function's culture for the next 15 years, including after that VP has left.
- London is shaped the way it is because it grew around Roman walls and medieval gates. Modern road planners can't easily undo Iron Age decisions.
- VHS beat Betamax not because it was technically better but because of distribution decisions made early.
- JavaScript runs the web partly because it was the language Netscape happened to ship in 1995. There were better options. They lost on path.
For operators:
Early decisions in any organisation matter disproportionately. The decisions made in year 1 (who you hired, what tech you used, who your first customers were) constrain options for years. This is one reason why "what's the founder's background?" and "who were the first 10 employees?" are sharper investor questions than they look.
When you can't understand why something is the way it is, ask what the world looked like when the decision was made. Sometimes the original logic is still valid (see [chestertons-fence]). Often it isn't, but the cost of changing now exceeds the cost of staying. Both can be the right answer, but you can only tell which by understanding the path.
Path dependence is also a humility lesson. A lot of what looks like clever strategic positioning is actually just where the company happened to land because of early choices. Some of the most successful companies admit this freely. Most don't.
Examples in the wild
Microsoft Windows still carries 30+ years of backward compatibility. There's code in Windows 11 handling edge cases from Windows 95. Each version had to support what came before, which constrains every new release.
Family businesses often look strange from outside because of decisions made by founders 80 years ago. Sometimes those decisions are still adding value. Sometimes they're holding the company back. Always worth understanding before investing.
Your network of close friends is heavily path-dependent. The friends you have at 40 are mostly people you met at jobs and schools you happened to attend earlier. Small changes in where you went would have produced very different friend groups.
Path dependence is one of the mental models we apply through real cases inside the Pareto MBA — a part-time program for professionals who want to think clearly about business.