The Space of American Public Opinion: Ideological Dimensionality in Models of Political Behavior

We use a novel approach to study how citizens structure their political preferences in ideological space. Specifically, we analyze belief systems in relational terms, modeling citizens' patterns of policy disagreements using nonmetric multidimensional scaling. The results support the proposition that a basic ideological space (consisting of a small number of interwoven policy domains) anchors the policy component of mass voting behavior. We show that voters---especially those meeting a minimum threshold of political sophistication---neither lack meaningful attitudes nor hold distinct preferences across a wide range of issues. Rather, they organize policy attitudes alongside relevant core values and affective evaluations in a common, low-dimensional cognitive space. A unidimensional approximation of these belief structures often exhausts the explanatory power of vote choice models, though our approach can also detect dimensions that may be relevant for certain voters or have the potential to evolve into meaningful cleavages.