Redundancy | Kaelan

A single engine plane can fly fine — until the engine fails. A twin engine plane costs more, weighs more, burns more fuel — but survives engine failure. The second engine is redundant in normal operation: you’re paying for capacity you don’t use. Until you need it. Then redundancy is the difference between inconvenience and death.

Biology is saturated with redundancy. Two kidneys, two lungs, two eyes. Multiple pathways to synthesize essential molecules. Overlapping genes that can compensate for each other’s failure. The human genome carries many sequences that seem useless — until environmental conditions reveal their value.

Redundancy trades efficiency for resilience. Every backup system is waste in the short term: unused capacity, duplicate effort, parallel infrastructure. Accountants see cost; engineers see safety margin. The system that runs lean runs brittle. antifragility requires slack — resources held in reserve for shocks that haven’t happened yet.

Critical systems stack redundancy: multiple independent failures must occur before catastrophe. Aircraft have backup hydraulics, backup electrical, backup instruments. Nuclear plants have containment within containment. The probability of total failure multiplies: if each system has 99% reliability, two independent systems have 99.99%. Three give 99.9999%.

The problem: redundancy is expensive and its value is invisible. The backup that never activates looks like pure waste. Organizations under cost pressure strip redundancy first — because nothing bad happens, for a while. Then something bad happens, and there’s no backup.

The lesson generalizes beyond hardware. Financial reserves are redundant capital until a crisis. Cross-trained employees are redundant skills until someone quits. Maintaining relationships is redundant effort until you need help. Redundancy is insurance that doesn’t look like insurance — costly in peace, invaluable in war.