Social Security is the largest, and arguably most important, program in the federal government. It is a life-line for millions. For the rest of us the program is a set of never-ending, polarizing arguments.
The contentiousness is caused in large part by the number and conflicting nature of the urban legends surrounding the system. Everyone has a fact that is someone else's myth.
These convictions about the program shape who voters elect, and seriously limit what candidates are willing to say to the electorate. These beliefs have so penetrated the public conscience that actual policy makers are left herding unicorns.