That is, their lack of intelligence causes them to often be annoying, because they try to defend stupid propositions as if they were a reasonably intelligent person.
EDIT: 2. Is there a semi-polite way of telling such a person that they aren't that bright so that they don't remain so oblivious to their own stupidity?
I realize that this is probably asking a lot. If there was a good solution, then maybe we could prevent the stupids from running rampant in society.
3. FICTION RECOMMENDATIONS. What good utopian/dystopian works of fiction (not necessarily books) are there that concern a society with a class system based on intelligence?