Quantifier Negation
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
~(x)Fx :: (∃x)~Fx, and ~(∃x)Fx :: (x)~Fx.
Show
"Not everything is F" means something isn't. "Nothing is F" means everything isn't.
Watch for
Pushing ~ through a quantifier flips it. De Morgan's rules (204), one level down — same flip, same forgetting-hazard.