Untangling polarization in politics through Network Science

Abstract

Polarization is a prominent theme in U.S. politics, with a commonly held view that the level of polarization in political discourse has increased substantially in recent years. Here we want to investigate to what extent this is the case. Using the Poole and Rosenthal W-NOMINATE scores, it is possible to analyze political choices to gain insights into legislators' political beliefs. Placing legislators on an ideological spectrum reveals the distance between their beliefs, which can be translated into a measure of polarization. This can be done through various measures, including the bimodal coefficient, which shows the bimodality of the distribution.

We illustrate how polarization changes in the U.S. political landscape from 1973 to the present day. Dividing our data into multiple political themes we analyze changes in polarization per theme in this temporal frame. Our analysis indicates significant fluctuations between consecutive congresses, influenced by notable historical events. Nonetheless, taking the full temporal aspect into account we can detect a definite increase in our measurements of political polarization over our larger time frame. This nuanced understanding of political polarization dynamics supports views of increasing polarization while challenging the perception of a steady rise in all aspects of legislative behavior.