Are Political Parties Growing Apart?

Applying mathematics to study trends in politics bears a resemblance to predicting weather and climate. There are so many unknown and unspecified variables, that at best it is only possible to make statistical guesses about the future.

There have been a number of models to predict presidential election outcomes, models that are generally driven by economic data. These models predicted a sweeping victory by Vice-President Al Gore in the 2000 presidential election. Many in 2000 thought that such models represented political destiny and did not appreciate that the models predict a statistical result. All other things being equal, one would have expected a Gore landslide victory, but all other things are never quite equal.

Nonetheless, political models and mathematical descriptors of political situations, as long as they are swallowed with a suitably large block of salt, can illuminate important and interesting trends.

Jordan Ellenberg in Slate magazine [1] recently called attention to work done by Keith Poole of the University of Houston and Howard Rosenthal of Princeton University who have tried to track the political polarization between the parties using roll call votes from 1879 to the present [2].

If we presume political affiliations are like grapes, people with similar views bunch together, we should be able to find a set of orthogonal axes in an ideological space revealing where Democrats and Republicans cluster. If the parties become more polarized, the distance between clusters of Democrats and Republicans in this space should increase. When polarization decreases, the clusters should begin to overlap. For example, one could find a few Republicans that are closer in their votes to the center of the Democratic cluster of votes than a few Democrats and visa versa.

Poole and Rosenthal found that the most explanatory geometric description of roll call votes rested on two dominant ideological axes. The first axis separating Democrats from Republicans was the traditional split based on belief on the appropriate extent of government involvement in the economy. On the left extreme of the axis would be economic Socialists and on the right extreme would be economic Libertarians. The second axis rested on differences in voting patterns on racial issues. While Republicans were generally on the side of more racial neutrality in government policies, Democrats through much of the twentieth century, were split along a North-South division. Northern Democrats and Republicans resembled each other in voting patterns racial matters, while Southern Democrats generally voted to maintain the social structures separating the races. As a consequence, the net polarization between the parties was smaller.

Go To Page: 1 2 3