1. Send him a nice sympathy card telling him you're sorry about the death of his brain.
2. Tell him that he's why you're against partial brith abortion -- apparently doctors removed his brain when he was being born.
(Actually....)
3. Thank God you are intellectually blind and stupid like he is.
4. Thank God you are not his child.
5. Thank God you have a sense a humor.
6. Thank God that you can still love your demented uncle.
7. And thank God your uncle isn't running for President. (Your uncle doesn't look French and have a daisy hanging from his zipper, does he?)
The best way to convince somebody is to let them convince themselves....
Tell him that YOU AGREE with every point he is making; his calm, deliberate recitation of his points leaves any alternative conclusion moot; if you were in a courtroom as a juror before him, his performance would lead you to only one conclusion....emotion is more important than truth and THAT must be why he is such a successful trial attorney.
Finally suggest that if he wants to change to a factual discussion, you and he might arrive at a different conclusion.