Michael Lopp wrote something yesterday in the useful-not-true category:

[…] I liked to describe humans in stark, clever ways. This often took the form of a “THIS or THAT” black-and-white structure, but I was 100% clear that the answer to humans was a hard-to-define grey area. My job was to get you to think, not to define every possible configuration of human behavior.

Derek Sivers had a similar idea:

Use what you learned from jigsaw puzzles. Start with the edges. Come up with extreme and ridiculous ideas that you’d never actually do, but are good for inspiration and finding the middle.

They are writing about different settings — Lopp about figuring out what’s already there, Sivers about creating something new — but the approaches are similar: to get to the grey area, first figure out the edges. This also tends to be my approach, but it is not how many people think and if you are to avoid painful misunderstandings better have a preamble ready.