I was given the sentence:
There is at least one person on earth who does not know logic
and was tasked to negate the sentence. I understand from class that existential quantifications become universal quantifications when negated.
The there is at least one person must become either everyone or nobody due to the aforementioned requirement of quantification negation.
However, examples in class have now confused me as to the desirable sentence structure of a negated predicate. Thus, I have four possibilities for the most accurate negation of the existential quantification:
Nobody on earth does not know logic
Everyone on earth knows logic
Nobody on earth knows logic
Everyone on earth does not know logic
Which sentence would you deem the most correct when negating the original predicate and why?