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 g enerally continued to downplay the role of ideology and partisan attitudes in explaining the behaviour of politicians. Why? We argue that this situati on is explained by a combination of instrumentalist conceptions of behaviou r that neglect attitudinal motivations, and methodological problems followi ng from the scarcity of data which measure ideology and partisanship separa tely from the behaviour they putatively explain. To address these problems, we employ original data on a state legislature to allow us more direct ins ight into such matters. Independent measures of ideology and partisan attit udes are found, as expected, to have a strong empirical association, but no netheless also to have identifiable and separate impacts on the voting deci sions of legislators. Our findings underscore both the importance of ideolo gy and partisan attitudes to an understanding of legislative decision-makin g and the value of developing independent measures of these concepts wherev er possible.