Friday, December 30, 2005


Why do geese and other birds fly in V-formation? Several different explanations have been suggested.
  • aerodynamic advantage
  • protection from predators
  • communication - they can see one another better
  • expresses social relationships - pecking order, dominance
[Sources: Ask a Scientist, New Scientist, Wikipedia]

Many people seem to think there should be a single correct answer to this kind of question. But POSIWID doesn't make this assumption. Instead of one strong and self-sufficient purpose, we may well find two or three weaker but mutually reinforcing purposes.

In order to prevent this misunderstanding, perhaps we shouldn't gloss POSIWID as the purpose of a system is what it does but rather a purpose of a system is what it does.

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