In trying to understand what it's all about I stumbled across this link which I am happy to share - please feel free to comment..
http://www.bbc.co.uk/news/world-us-canada-39133677
In 1989, Scottish political scientist Richard Rose noted that most American historians endorse exceptionalism. He suggests that these historians reason as follows:
America marches to a different drummer. Its uniqueness is explained by any or all of a variety of reasons: history, size, geography, political institutions, and culture. Explanations of the growth of government in Europe are not expected to fit American experience, and vice versa.