But notice that the same objection applies to the possibility of grammatical conventions in language. We either need to know of the infinite number of grammatical instances of the form ‘(Subject) is a (Predicate)’,or we would need meta-linguistic rules of substation to derive its instances from the general grammatical grammatical convention. But we evidently do not need such additional rules to speak, because the very scheme is a ‘production rule’. The sole function of such a rule in a natural language is to generate instances. Likewise, logical schemes are rules which guide the production of logical truths.