In a rational world, there should be not conflict in discussions between you and your brother even if you're attached to different parties. Up until around the time of Nixon, Democrats and Republicans got along and could have friendly debates, or at least where I was raised.
Some extremely nasty right-wing operatives realized if they ever wanted to achieve significant power, they would have to create chasms between numerous groups of people in America....therefore divide and conquer. That's what they've done over the last 50 or so years and now it's come down to families and neighbors not even speaking.
This is a good Berkeley article from way back in 2003 by George Lakoff on this subject that still applies today:
Link: https://www.berkeley.edu/news/media/releases/2003/10/27_lakoff.shtml
I sincerely hope you can point this out to your brother and find common ground to allow him to see what Republicans have done to our society.
We have truth on our side..........
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