The syllogistic fallacy of exclusive premises (two negatives), due to not being able to deduce ex nihilo (affirmative conclusion from negative premise), should also require existential import (although I think we need to upgrade to three kinds of import: ontic, deontic, and thetic import - Defining the Imports) of all terms, including universals—should consider a premise with an empty term/category to be unsound (that would mean the REAL existential fallacy is a premise that is unsound or falsely (due to lacking import) presumed sound, rather than the requirement of import itself being fallacious). See Wilford Hodges” book, Logic, pages 132 to 134, regarding designators requiring a purely referential occurrence, a primary reference. This is basically the same thing as existential import.
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