Full Idea
One can distinguish at least two quite different senses of logic: as an instrument of demonstration, and perhaps as an instrument for the characterization of structures.
Gist of Idea
Logic is either for demonstration, or for characterizing structures
Source
Leslie H. Tharp (Which Logic is the Right Logic? [1975], §2)
Book Reference
'Philosophy of Logic: an anthology', ed/tr. Jacquette,Dale [Blackwell 2002], p.37
A Reaction
This is trying to capture the proof-theory and semantic aspects, but merely 'characterizing' something sounds like a rather feeble aspiration for the semantic side of things. Isn't it to do with truth, rather than just rule-following?
Related Idea
Idea 15407 Formalising arguments favours lots of connectives; proving things favours having very few [Burgess]