Avashai Margalit, "Open Texture"

The intension of a sentence should be a function only from those worlds that are compatible with our "hard core" beliefs to truth values, not from all possible worlds. Open texture is the fact that the set of hard core beliefs is "fuzzy", so it won't be obvious whether certain worlds are compatible with them or not, and so there will be situations where we can grasp the meaning of a sentence and still not know whether or not it applies in a particular world.