Internal-external distinction

The internal–external distinction is a distinction used in philosophy to divide an ontology into two parts: an internal part consisting of a linguistic framework and observations related to that framework, and an external part concerning practical questions about the utility of that framework. This division was introduced by Rudolf Carnap in his work Empiricism, Semantics, and Ontology. It was subsequently criticized at length by Willard Van Orman Quine in a number of works, and was considered for some time to have been discredited. However, recently a number of authors have come to the support of some or another version of Carnap's approach.

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 entities. The discussion of a proposition within a framework can take on a logical or an empirical (that is, factual) aspect. The logical aspect concerns whether the proposition respects the definitions and rules set up in the framework. The empirical aspect concerns the application of the framework in some or another practical situation.

“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. A question of this kind may be either empirical or logical; accordingly a true answer is either factually true or analytic.”

The utility of a linguistic framework constitutes issues that Carnap calls 'external' or 'pragmatic'.

“To be sure, we have to face at this point an important question; but it is a practical, not a theoretical question; it is the question of whether or not to accept the new linguistic forms. The acceptance cannot be judged as being either true or false because it is not an assertion. It can only be judged as being more or less expedient, fruitful, conducive to the aim for which the language is intended. 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. the analysis, interpretation, clarification, or construction of languages of communication, especially languages of science.”

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