To Err is Not Always Human

I'm co-teaching "computer networks" this quarter, with my colleague Anne Rogers. While preparing, I came across the following anecdote about how a "system" must be able to tolerate imperfect behavior:

Larry David (on the show "Curb Your Enthusiasm") was frantically looking for a DVD case, but could not find it.

LD: "I don't know what happened. I have a system. I put the DVD in the player, and I put the case on top of the player. But now it is gone."

Friend: "That's not a system. A system is - you buy a bunch of empty DVD cases and put them next to the player."

More seriously, I read yesterday a fascinating article by Richard Cook on the causes of errors in complex systems such as hospitals, and the tendency to blame these errors on "operators." Cook notes that: