Full Idea
Defining logical consequence in the way Tarski does is a rather meagre result, treating an argument as a black box, observing input and output, while disregarding inner structure. We should define logical consequence on the basis of valid arguments.
Gist of Idea
Logical consequence isn't a black box (Tarski's approach); we should explain how arguments work
Source
Dag Prawitz (On the General Idea of Proof Theory [1974], §2)
Book Reference
'A Philosophical Companion to First-Order Logic', ed/tr. Hughes,R.I.G. [Hackett 1993], p.217