Young is dumb because they don't actually know any better.
Old is dumb because they THINK they know better because they've lived through it all. You can't change their minds on most things.
My dad is the exception to this rule. When I was little my dad was a staunch conservative, always voting party lines, against gay marriage and abortion etc. Now he is in his 70's and has dramatically changed his viewpoints... accepts gay marriage (finding out his sister was a lesbian helped this along), is pro-choice now and supports more liberal politicians. He still holds many conservative views, but will vote on the person not the party. Some people do change, but I think for the most part older people don't change much at all.