ABSTRACT
As we saw in Chapter 1, probably the most time honored and universal way of using spatial language to describe the policy positions of political actors has been to describe these as being to the “left” or to the “right” of the political spectrum. This political spectrum is an explicit or implicit “left–right” scale that defines a spatial language understood by almost every political commentator, from the interested lay observer, to the hyper-connected political insider, to the political scientist who stands aloof from politics and attempts to describe this from a distance. As we saw in Chapter 2, many spatial models of politics are “one-dimensional.” This may be for reasons of tractability, as complex models of political competition can be hard enough to specify and solve in one dimension, let alone many. It may result from a substantive judgment that, for a given political system, one key policy dimension is sufficient to capture most of what is going on. Putting all of this together, there is no doubt that the notion of a single “left–right” political spectrum is both widely understood by informal political commentators and widely used by many who theorize about politics – at least as a first step in specifying and solving complex models. It is therefore both theoretically important and practically useful for us to be able to produce reliable and valid estimates of the positions of political actors on a well-defined left–right scale.
