Since the pioneering work of Anthony Downs, students of party competition have focused on the ideological positioning of political parties. While Downs’s formulation mentioned the possibility of political vagueness, scholarship turned to the systematic study of positional ambiguity only years later. The aim of ideological blurring is the broadening of partisan attraction beyond voters who share the party’s specific political view. The approaches to blurring fall into two strands. One, originating from studies of American politics, sees position blurring as an attempt to widen the scope of appeal on one ideological dimension, which may prove a political flaw in need of a clarifying remedy. A second strand, deriving from studies of European party systems, sees position blurring as a multidimensional strategy of deflecting voter attention to other political issues on which the party is more favorably placed.

Kyung Joon Han’s new book, Rationality of Irrationality, is a successful unification of the theoretical insights from both strands of the literature and lays a systematic empirical foundation for understanding the causes and consequences of ambiguous party positioning. The book starts with the observations of students of American politics about the potentially practical, but normatively questionable consequences of blurring. It then turns decisively to the multidimensional conception of politics as a struggle over the composition of political interests, where parties strive to shift voters’ attention to areas where they are viewed favorably, and on which their voter base is in unified agreement.

The core argument of the book is twofold. First, it rephrases the prevailing conclusions of the blurring literature that ``parties blur their position on an issue … when their comparative disadvantage on the issue is revealed” (p. 19). Second, and more original, is the idea that ``party-competition environments”—the context of the party system—influence the effectiveness of position blurring (p. 19). Unlike past works, Rationality of Irrationality theorizes the possibility that parties simultaneously emphasize and blur a political issue in a context when this issue is too broadly salient to ignore.

The methodology of the book is a similarly impressive combination of approaches. The book marries the study of political supply—the clarity of party positioning—with more sociologically oriented studies of voter demand, focusing on the attitudes and electoral behavior of divergent social groups, such as manual workers and small shop owners. In terms of measurement, Han relies on voter surveys, particularly the European Election Study, and party-positioning data from the Chapel Hill Expert Survey, complemented with information from the Manifesto Project. To capture positional ambiguity, the book primarily uses the standard deviation of expert placements of parties, while corroborating it with a positional ambiguity score taken from party manifestos.

The findings of the book can be summarized in three points. First, blurring works. The book demonstrates that blurring leads to voter uncertainty over party positioning, and that ``voters reduce their consideration of an issue … in their vote choice as political parties blur their positions” (p. 54). Second, blurring is issue specific. In line with past works, blurring occurs with issues on which the parties are seen as less competent, and where their supporters are divided. Originally, the book shows that blurring is more likely to occur on issues that are nonetheless systemically salient. This is an important finding, infusing the study of ambiguity with much-needed consideration of broader political context. Third, blurring blinds. Focusing on radical right and social democratic parties demonstrates that blurring removes the core electorates’ consideration of party-voter distance on blurred issues. Manual workers and small shop owners are thus willing to support radical right parties despite their incongruence on economic issues, while other manual workers support social democratic parties despite their disagreement over immigration policy.

The virtue of Rationality of Irrationality lies in its successful theoretical synthesis, and in its systematic and convincing empirical demonstrations of how and when blurring works. The innovation of the book is its insistence on the contextual nature of blurring, which is most common in situations where parties cannot shy away from engaging political issues due to their preeminence in public debate. The book is also rich with diverse examples of specific tactical choices of concrete political actors, which brings the acts of positional blurring to life.

Given its quantitative methodological approach, and its reliance on previously existing data, the book cannot engage several important questions about strategic blurring that stand out. First is the question of how voters actually perceive blurred party positions. The book, like past works, suggests that blurring can take on different forms, such as vague statements on the issue, multiple inconsistent statements on the issue, statements that combine similar issues in atypical ways. The book assumes, again with much of the literature, that ``if voters do not possess enough information on an issue, they rely more on other issues or nonpolicy features” (p. 24). This is likely the case, but it may also be that some voters engage in wishful thinking and project (their) positions onto the party, perhaps with certainty. The duplicitous economic statements of many radical right parties aim to shift voter attention towards immigration only partly. Calls for economic support for native young families combined with calls for cutting taxes, for example, also hope to instill in voters a certainty that radical right parties would support young families and cut taxes. A young parent may thus be as confident about the party’s (left-leaning) views on family allocations, as a small shopkeeper may be about the party’s (right-leaning) tax policy. Creative use of survey experiments may be able to assess how exactly diverse types of ambiguity influence the positional perceptions and subsequent political calculus of voters.

Second, the book references other works contending that there is deliberate and strategic use of blurring on the part of political actors. Yet it remains unclear how exactly political elites go about building ambiguous profiles. Do they explicitly plan it in smoky backrooms? Or is it rather a political hunch that leads them to express different positions to different audiences? Ethnographic work and interviews with (retired) politicians may provide a useful glance into the making of ambiguity.

Finally, Rationality of Irrationality takes a normative position, arguing that blurring is deplorable as it severs the linkages between the people and their representatives (p. 12, pp. 169-70). The findings of the book itself undermine this view and throw into question the irrationality of positional ambiguity. Following the multidimensional approach to political competition, the book, in line with past work, argues that blurring is primarily a mechanism of deflecting attention to advantageous issues; no party thus blurs everything. Radical right parties are unambiguous champions of national sovereignty and restrained immigration, while socialist parties are clear defenders of generous welfare systems. And voters dominantly support them because of these stances. Blurring some issues thus does not remove policy considerations altogether and does not dissolve parties of their representative responsibilities in general. Perhaps we should not disparage political elites for rationally employing rhetorical and strategic tactics that work. Indeed, decrying blurring on the part of politicians may be as futile as decrying flying on the part of birds.

Overall, the Rationality of Irrationality is an important contribution to our understanding of the strategies of political parties seeking to navigate the complexities of diverse electorates—a must-read for all students of political competition.