In the Tractatus, Wittgenstein draws a demarcation among meaningful sentences (1), the meaningless propositions of logic (2: sinnlos sätze) and nonsensical propositions (3: unsinnig sätze).
1) Sentences of the first type are informative since I can decide to express agreement or disageement with the truth-possibilities of their constitutive indipendent elementary sentences;
2) Tautologies of logic suffer from being informative vacuous and therefore I have no other option than expressing agreement with them all;
3) the nonsensical propositions have no truth possibilities can be referred to, for they lack any correct logical form.
Given the assumption above, in accordance with the extensional scheme of the Tractatus, Wittgenstein had to manage with the problem of the perfection of natural language in order to comply with it, since natural language is affected by vagueness ->
Both Russell and Wittgenstein recognized the phenomenon of vagueness in ordinary language; however, their explanations of it differ substantially. The standard explanation of vagueness is most often stated in terms of unclear cases of the application of a predicate (a word) or con- cepts that do not have sharp cut-off points.
I'm not sure to have grasped what a "vague sentence" precisely is and so I need some examples; may I considere, for instance, the following? -> "This chair is light brown"
It seems to me it is an example of "vague" sentence of natural language since the predicate "light brown" is not a borderline case of brown results and therefore it doesn't have a precise definition: is it correct to say that?
If it is, may I say that such sentence is still meaningful, for it has an underline logical form which is different from the surface grammar, but I can still fully interpret it semantically?