I was speaking with a philosophy professor today and he suggested that the party switch was not real, pointing to the fact that apparently only one Democrat became a Republican after the passage of the civil rights act as proof. So, I want to know if he is right as I have always believed that the party switch did occur. And, if the party switch did occur, how and why did it happen?
Further discussion is always welcomed, but while waiting for that you may be interested in the Changing role of Republicans and Democrats section of the FAQ. There are some excellent answers from u/erissays and /u/samuel_gompers.