It's not just a matter of people taking the phrase literally: - by a plain reading it's clearly singular; seeing beyond that requires at least some effort (e.g

It's not just a matter of people taking the phrase literally: - by a plain reading it's clearly singular; seeing beyond that requires at least some effort (e.g. curiosity, education... but also authority, responsibility, time) - there are lots of people dealing with complex system failures that haven't been exposed to any of the relevant theory... tech folk, but also mgmt, comms (which can be more problematic) - concluding with a single cause is frequently less work - concluding with a single cause is frequently convenient (e.g. pinning the blame on a single vendor, component, person) That's why it's helpful to introduce terminology that points everyone's brains in the right direction from the very start, e.g. contributing factors. (also common sense isn't real)