Full Idea
The 'vague' might be defined as that to which the principle of contradiction does not apply. For it is false neither that an animal (in a vague sense) is male, nor that an animal is female. No communication between persons can be entirely non-vague.
Gist of Idea
All communication is vague, and is outside the principle of non-contradiction
Source
Charles Sanders Peirce (Critical Common-Sensism [1905], I)
Book Reference
Peirce,Charles Sanders: 'Philosophical Writings of Peirce', ed/tr. Buchler,Justus [Dover 1940], p.295
A Reaction
Note that he makes vagueness largely a matter of the way we talk, which is David Lewis's approach, and looks right to me.