The phrase does not make more sense even if we go all the way back to Beers. I certainly don't feel alone in not understanding how he went from his (fair) observation that "[There's] no point in claiming that the purpose of a system is to do what it constantly fails to do" to his more controversial conclusion: "The purpose of a system is what it does (aka POSIWID)".
Surely, there were many more sensible (but perhaps less quippy) stops between the two.
The phrase does not make more sense even if we go all the way back to Beers. I certainly don't feel alone in not understanding how he went from his (fair) observation that "[There's] no point in claiming that the purpose of a system is to do what it constantly fails to do" to his more controversial conclusion: "The purpose of a system is what it does (aka POSIWID)".
Surely, there were many more sensible (but perhaps less quippy) stops between the two.