Sorry UIP, but you're quite wrong. In formal logic, "all X are not Y" does not in fact mean "no X are Y" -- rather, it means "not all X are Y.

Jeez, Patricia ~ what is it your love-making that leads you to PITE afterward? Too muh verbalization? Or not enough? ;->

I want to know why no one called Whitney on her so-called "rule"....

Still, Bill, plausibility does not always equal correctness.

Actually, John, Abby Normal's analogy with speed limit rules is right on target. You failure to see the clarity of the analogy goes directly to her opening suggestion: as you take the stance of a linguist (observer) rather than grammarian (prescriber), then your opinions and viewpoints are irrelevant -- and in fact distracting -- in any discussion of what is CORRECT. So if the query is "which is correct", your response is not germaine.

By the way, I love your user name, Abby!

with respect to Voltaire ~ because, after all, how can one NOT respect Voltaire? ~ I agree with Ryan on this, and Abigail. Thanks to you both in seeing it and expressing it simply and clearly.

... and then there is this usage of "should"--
"What would you say should I decide to arrive earlier than planned?"

That was awfully cavalier of you, Emily!

Yes, still a purist.
Sorry.

I'm always amused ~ and amazed ~ by how many people posting declarations of "fact" on this website use appallingly bad grammar, spelling and punctuation in their posts!