According to Rudolf Carnap, we should distinguish between internal and external questions. Let us say that,

With respect to various expressions, A linguistic framework is a set of rules for using for those expressions.

Thus, an internal question is a question about whether x exists given a linguistic framework of rules governing the use of 'x'. An external question is a question as to whether it would be useful to adopt the use of 'x' with those rules.

Suppose one asks but does x exist independent of the linguistic framework? Carnap might argue as follows:

One can answer an existence question only if there are rules for determining whether x exists.
External questions regarding x occur independent of a linguistic framework regarding x.
Therefore, external questions regarding x are not existence questions.

Questions: (a) Is this sound argument? (b) Why or why not?