Ideology, Partisanship and Decision-Making in a Contemporary American Legislature

Despite widespread agreement that American politics in the 1980s and 1990s has become more ideological, with more deeply entrenched partisan divisions, studies of legislative decision-making within the American context have generally continued to downplay the role of ideology and partisan attitudes in explaining the behaviour of politicians. Why? We argue that this situation is explained by a combination of instrumentalist conceptions of behaviour that neglect attitudinal motivations, and methodological problems following from the scarcity of data which measure ideology and partisanship separately from the behaviour they putatively explain. To address these problems, we employ original data on a state legislature to allow us more direct insight into such matters. Independent measures of ideology and partisan attitudes are found, as expected, to have a strong empirical association, but nonetheless also to have identifiable and separate impacts on the voting decisions of legislators. Our findings underscore both the importance of ideology and partisan attitudes to an understanding of legislative decision-making and the value of developing independent measures of these concepts wherever possible.