 Here is an illustration of how that sort of strategy might go. Let S be some object in the series that clearly seems to be a stone, let NS be an object that clearly seems to be a non-stone, and let BS be an object that seems to be a borderline case of being a stone. One might suggest that ‘stone’ is vague as a result of there being a range of candidate precise meanings (or “precisifications”) for the word ‘stone’,