Normal Accident Theory (NAT)
Core Idea:
In complex, tightly coupled systems (like nuclear plants, aircraft, or financial systems), accidents are inevitable — not due to operator error or design flaws alone, but because of the system's inherent complexity.
Key Concepts:
1. Complex Interactions
Many components interact in unpredictable ways.
Failures can cascade in untraceable sequences.
2. Tight Coupling
Processes are time-sensitive and interdependent.
One failure can quickly affect others, leaving little time to respond.
3. Normal Accidents
These systems will eventually fail in ways that can't be fully prevented or predicted — hence, "normal."
4. Redundancy Isn't Always Safer
More backups can add complexity, introducing new failure paths.
Examples:
Three Mile Island nuclear accident
Chernobyl
2008 financial collapse
Aviation systems
Perrow's theory argues that in some systems, risk can't be engineered out, so they may not be worth operating at all unless society accepts the potential for rare but catastrophic failure.
