To understand the red/blue polarity in politics and other places, study the chakra system. Red and blue are the opposite ends of the energy spectrum that underlies our own energy systems and they represent mentality on one and and emotionality on the other end. In most people these two polarities of self are in conflict/war/struggle and so we see this reflected in politics. Whether this was done deliberately by the system designers or just occurred unconsciously, I'm not 100% sure.