H. P. Grice on the and THE

 Grice: "I propose to use 'the' for the regular 'the.' 'THE,' by contrast, will represent an irregular 'the' -- attached to the thing which the utterer can actually REFER, rather than merely ATTRIBUTE.

The dog is shaggy.

THE dog is shaggy.

It all boils down to the utterer's 'dossier' -- "a concept which apparently fascinated G. E. J. Evans, of Oxford."