The theory of issue evolution predicts that the dimensional space of party competition is simple. We contrast this prediction with the expectation that a complicated multi-party system, such as the one in France, produces a more complicated dimensional structure. To test this claim, we examine the longitudinal structure of the policy preferences that underlie public opinion in France. Using surveys of preferences as a basic data source, we are able to extract two latent dimensions that almost fully explain the reported preferences. Both dimensions are defined by the left–right structure of the French party system. Whereas one is the traditional socioeconomic domain, the other comprises a wide array of new cultural issues. The orthogonal solution, however, does not produce the expected socioeconomic and cultural dimensions. Thus we impose our prior belief in the socioeconomic and cultural content and rotate the two dimensions independently to maximize fit with the two prior dimensions. We show that the same two-dimensional structure is also present in cross-sectional data, and can be used to position parties in the two-dimensional space. Moreover, we find that the two dimensions are closely connected, despite their completely different content. The explanation, which arises from the theory of issue evolution, is that the meaning of left–right is dynamic as well as elastic and incorporates new issues as they arise.
