I submit that many of us would probably at least entertain the thought of writing off a portion of the species whose attitudes don't agree with ours, and with whom we may have had unpleasant encounters with during our formative years. (People who recently posted rants about stupid backwards red-staters, I'm looking at you.)

Some merely go so far as to extend this to the whole species and declare that humans are inherently, irredeemably corrupt, based on the examples they see around them and any negative feelings they may have about themselves.