 We can develop that thought as follows. The logician’s task is to capture the consequence relation on natural language sentences, but it usually simplifies things to pay attention only to particular expressions in those sentences, such as conjunction, negation, and disjunction, say, or those expressions plus the universal quantifier and identity. Whichever set of symbols we select as our so-called logical constants, the meanings of all the other expressions in the sentences—the non-logical expressions—are determined by the interpretations (or, as we call them in the GTT, ‘cases’), and since we are quantifying over all such interpretations, in effect we are simply ignoring the meanings of all non-logical expressions. 