  The upshot is that a grammatical demarcation of logical constants will not impose significant constraints on what counts as a logical constant unless it is combined with some principle for limiting the languages to which it applies (excluding, for example, languages with the operator “¢”) and privileging some regimentations of their grammars over others (excluding, for example, regimentations that treat truth-functional connectives as members of a small lexical category).  Quine’s own approach is to privilege the language best suited for the articulation of scientific theories and the grammar that allows the most economical representation of the truth conditions of its sentences. Thus the reason Quine holds that logic should restrict itself to the study of inferences that are truth-preserving in virtue of their grammatical structures is not that he thinks there is something special about the grammatical particles (in an arbitrary language), but rather that he thinks we should employ a language in which grammatical structure is a perspicuous guide to truth conditions: “what we call logical form is what grammatical form becomes when grammar is revised so as to make for efficient general methods of exploring the interdependence of sentences in respect of their truth values” (1980, 21).