Heck, it doesn't even fall under the first because:
From: SovietOmega | #118
that rests on grounds insufficient to produce complete certainty.
That doesn't really fall under "Gravity doesn't exist" being an opinion.
Saying gravity doesn't exist is just factually wrong.
It's not really a matter of opinion.
Saying "I believe 2+2 = 5" isn't an opinion.
It's simply factually wrong.
--
"Why must we always choose between certain death and probable death?"
"I'm in an epic battle to the death, FIGURE IT OUT YOURSELF!"