State of Disunion

Much of the literature and methodology of polarization emphasises party mean-ideology points and/or party unity. Using this approach alone neglects a vital aspect of polarization; namely, remaining ideological variety and party disunity among both Democrats and Republicans today. I measure both of these factors in a new methodology, the Independence (I)-Score. This methodology scores each legislator in a single figure on how often they vote against their party, and also how moderate they are ideologically. This blends elements of DW-NOMINATE and party unity scores into one scoring system, which emphasises those left behind by polarized parties, who are also under-represented in the literature. I argue that these independent outliers may yet play a key role in bridging the gap between the two parties, whilst the I-Score methodology finds their decline to be a crucial aspect of polarization and demonstrates why. This is a fresh take on the history and problems of polarization, particularly because it considers the vital (if not numerically large) groups of moderates who still remain in Congress. In a time when intra-party debates are increasingly important, the I-Score provides a new take on polarization to supplement the use of one-dimension, left-right party-average points. In Chapter One I provide an overview of the polarization literature to date. In Chapter Two I survey the state of party heterogeneity and ideological variety in the 110th Congress. In Chapter Three I consider the endangered and numerically weak groups which ‘modify’ their party behaviour and provide some much needed high I-Scores, I assess how far these groups alleviate polarization. Finally, in Chapter Four, I conclude with an analysis of three issues which demonstrate how polarization works on typical domestic themes, whilst breaking down along non-party lines on national security. I also suggest further refinements for the I-Score method, and provide ideas for its future use.