Wittgenstein AND/OR Family! It's a common misunderstanding that Witty is an advocate for 'vagueness' or somesuch. Rather, he reckons that we continually or often look for 'exactitude' in the wrong place. My favoute example he gives is of someone saying 'wait for me roughly there'. And then he has some hypothetical idiot trying to specify exactly where 'there' is: its boundary, how far 'roughly' should extend from the point that is specified and so on. But of course, the non-idiot will know very well that when someone says 'wait for me roughly there', the idea is that one waits where they can be found again without too much hassle. The idiot here is the philosopher (or a particular kind of philosopher, I'd rather say). As Witty puts it, there's nothing vague about it. It's only when we have a false idea of 'the exact' that his take on language seems to brook the 'vague'.
PI §87: "The signpost is in order a if, under normal circumstances, it fulfils its purpose"; §88. "If I tell someone “Stay roughly here” - may this explanation not work perfectly?"; §98: "On the one hand, it is clear that every sentence in our language ‘is in order as it is’. That is to say,
we are not striving after an ideal, as if our ordinary vague sentences had not yet got a quite unexceptionable sense, and a perfect language still had to be constructed by us. - On the other hand, it seems clear that where there is sense, there must be perfect order. —– So there must be perfect order even in the vaguest sentence".
There's a mathematical analogy to be drawn here. The idea is that language does not function as a well-ordered set. Every use of language is a matter of partial ordering: §97: "We are under the illusion that what is peculiar, profound and essential to us in our investigation resides in its trying to grasp the incomparable essence of language. That is, the order existing between the concepts of proposition, word, inference, truth, experience, and so forth. This order is a super-order between - so to speak - super-concepts". But concepts and words are singular. they respond to, and arise from, particular lived situations. And words and meanings cannot be mapped onto some trans-historical order that could be clarified once and for all. In every case it must be asked: does that word fulfil its purpose? And if so, it's exact as it can be.