 In view of problems of these and other sorts, some philosophers have proposed that the concept of a logical expression is not associated with necessary and sufficient conditions, but only with some necessary condition related to the condition of wide applicability, such as the condition of “being very relevant for the systematization of scientific reasoning” (see Warmbrōd 1999 for a position of this type). Others (Gómez-Torrente 2021) have proposed that there may be a set of necessary and sufficient conditions, if these are not much related to the idea of semantic “insubstantiality” and are instead pragmatic and suitably vague; for example, many expressions are excluded directly by the condition of wide applicability; and prepositions are presumably excluded by some such implicit condition as “a logical expression must be one whose study is useful for the resolution of significant problems and fallacies in reasoning”. To be sure, these proposals give up on the extended intuition of semantic “insubstantiality”, and may be somewhat unsatisfactory for that reason.