Each necessary, but only jointly sufficient

Etsy 现在的 CTO 前几年写的文章。production 出故障了,人们经常一厢情愿地想找出有且仅有一个 root cause,这样才好向上面交差。复杂的系统出故障了往往不止一个 root cause,有天灾当然也有人祸。

"... failures in complex systems require multiple contributing causes, each necessary but only jointly sufficient."

"Finding the root cause of a failure is like finding a root cause of a success."