Rudolf Carnap introduced the idea of a 'linguistic framework' or a 'form of language' that uses a precise specification of the definitions of and the relations between ontological entities.
The logical aspect concerns whether the proposition respects the definitions and rules set up in the framework.
“If someone wishes to speak in his language about a new kind of entities, he has to introduce a system of new ways of speaking, subject to new rules; we shall call this procedure the construction of a linguistic framework for the new entities in question.”“After the new forms are introduced into the language, it is possible to formulate with their help internal questions and possible answers to them.
Judgments of this kind supply the motivation for the decision of accepting or rejecting the kind of entities.”“the decisive question is not the alleged ontological question of the existence of abstract entities but rather the question whether the rise of abstract linguistic forms or, in technical terms, the use of variables beyond those for things (or phenomenal data), is expedient and fruitful for the purposes for which semantical analyses are made, viz.
A more formal statement of the internal-external difference is provided by Myhill: "A question...is internal relative to [a linguistic framework] T if the asker accepts T at the time of his asking, and is prepared to use T in order to obtain an answer; external otherwise, in particular if the question is part of a chain of reflections and discussions aimed at choosing between T and some rival theory.
[3][4] Quine's criticism of the internal-external distinction is found in his works On Carnap's views on Ontology and Word and Object.
Whether the statement that there are physical objects and the statement that there are black swans should be put on the same side of the dichotomy, or on opposite sides, comes to depend upon the rather trivial consideration of whether we use one style of variables or two for physical objects and classes.So we can switch back and forth from internal to external questions just by a shift of vocabulary.
In other words, Quine's position is that "Carnap's main objection to metaphysics rests on an unsupported premise, namely the assumption that there is some sort of principled plurality in language which blocks Quine's move to homogenize the existential quantifier.
"[8] "What is to stop us treating all ontological issues as internal questions within a single grand framework?
In other words, Hirsch agrees with Quine that there is an overarching language that we can adapt to different situations.
[17] But the poor mathematician translates it into equations, and as the symbols do not mean anything to him he has no guide but precise mathematical rigor and care in the argument.
[19] While Carnap claims such decisions are pragmatic in nature, external questions with no philosophical importance, Schaffer suggests we avoid this formulation.