  The fact that universal affirmatives with empty subject terms are false runs into a problem with Aristotelian scientific theory. Aristotle held that ‘Every human is an animal’ is a necessary truth.  If so, it is true at every time.  So at every time its subject is non-empty.  And so there are humans at every time.  But the dominant theology held that before the last day of creation there were no humans.  So there is a contradiction.