We need to think precisely about vagueness

DESPITE our attempts to define, measure and make life black and white, the world turns out to be unexpectedly vague (see “Kees van Deemter: The importance of being vague”). It’s not just that things we think of as well-defined are actually a series of approximations, like the metre. More profoundly, vagueness is a key part of communication: unless we get to grips with it, robots will never “talk” naturally to people and the much-hyped semantic web won’t work at all. Just as well, then, that we have finally started to think precisely about vagueness.