In his insightful new book, Christoffer Green-Pedersen asks what has happened to party politics in Western Europe. The once “frozen” class-based structure of party politics has thawed in recent decades, giving way to a new issue-based structuring of party conflict. In The Reshaping of West European Party Politics, Green-Pedersen offers a novel theory, called the issue incentive theory, to help explain why large mainstream parties choose which issues to prioritize and how such decisions change the landscape of contestation between parties.

The issue incentive theory posits that large mainstream parties—those parties most likely to serve in government or as the major opposition to government—are the main drivers of what Green-Pedersen refers to as the party system agenda, and as such, the focus should be on what issues such parties prioritize in their programs. The crux of the argument is that different issues offer different incentives to parties and only those issues that are deemed to support the voting and office-seeking motivations of large mainstream parties are likely to play a role in the party system agenda.

For Green-Pedersen, these incentives are based on three criteria. First, there are issue characteristics such as an issue’s salience and solubility. The more problematic a given issue is and the more measurable its effects, the more likely it is be an important issue on the party system agenda. Second, issue ownership matters: the degree to which a certain issue is perceived to be better addressed by a mainstream party, the more likely it is that the party will campaign on this issue. Finally, mainstream parties take into account how new issues will potentially effect coalition formation with other parties before choosing to elevate an issue to the point where it has an effect on the party system agenda. Taken together, these three criteria form a powerful analytical tool for helping us understand why some issues become part of the party system agenda and others do not.

It is widely accepted that party politics in Western Europe has changed over time and that a second dimension of political contestation, separate from the classic left–right ideological dimension, has gained prominence. However, there is less agreement on what this second dimension represents. This newer “social” dimension of contestation is understood to encompass a bundle of issues, including positions on immigration, the environment, globalization, and social lifestyle, to name a few. Green-Pedersen rightly points out that this second dimension is far less coherent than the classic left–right dimension, so much so that it may not even make sense to consider this set of issues in the aggregate. Rather, he argues, to understand why issues that fall under the label of the “second” dimension have become more prominent in party politics, we need to pay more attention to the issues themselves, as opposed to the more traditional approach of analyzing party positions on this dimension.

Much scholarly work has focused on explaining how and why the Western European party system has changed from a class-based to an issue-based structure over time; however, this book represents a departure from the bottom-up approach commonly used in the literature. This bottom-up approach views the changing nature of Western European politics as a function of newly formed social groups based on new conflicts in society, with political parties adapting their positions to fit within this new cleavage structure. These new social groups also give rise to new political parties, which are usually niche parties formed around one specific issue, such as immigration.

The issue incentive theory, however, is an extension of other top-down approaches to explaining shifts in party system agendas. The top-down approach is explicitly an elite-driven model of party system change, in which the introduction of new issues into the party system agenda reflects strategic decisions by parties regarding how they choose to compete for votes and seats. The issue incentive theory, although heavily influenced by other top-down approaches, provides a theoretical lens through which to understand why some issues and not others have risen to prominence in Western European party systems: it represents a novel addition to the elite-driven theories of party system change.

The debate between bottom-up and top-down approaches is, in some ways, a two- sides-of-the-same-coin affair. There is no doubt that aspects of both theoretical views are at play when trying to understand party system change: for an issue to meet the criteria spelled out in the issue incentive theory (party characteristics, issue ownership, and coalition considerations), there, by definition, must be some mobilization within the public around that issue. Parties obviously consider the public’s views and positions before deciding to compete electorally on a given issue. While Green-Pedersen acknowledges this to some extent, the role of public opinion is largely absent from his theory, even though issue characteristics are at least somewhat related to public opinion.

In chapters 7–10, Green-Pedersen walks us through the process of applying his theory to a variety of highly salient issues in contemporary Western Europe, such as immigration, European integration, the environment, education, and health care. These chapters make a compelling case for the utility of the issue incentive theory for understanding how and why some issues make it on to the playing field. I do think the case would have been even more compelling, however, if the author had illustrated how the electorate’s views on these issues have shifted over time as well. The empirical analyses in the book are exclusively related to the attention that parties give to these issues, absent the role of public opinion. Therefore, it is difficult to argue that shifts in the composition of the electorate’s views toward these issues are not important for understanding the strategic considerations of political parties.

The analyses in the book are also somewhat limited in that the author has chosen to focus on seven countries in northwest Europe. This choice makes sense, given the theory’s expectation of a stable party system with well-established mainstream parties, but it would be fascinating to explore how this theory performs in other contexts. Although there are clearly data limitations that also helped inform the choice of cases, the analyses in the book could be extended to other cases with some effort.

I find this last point to be more of a strength than a weakness, however. The issue incentive theory developed in this book will most certainly lead to a considerable amount of new scholarly work. The concluding chapter poses a handful of intriguing questions, many of which will undoubtedly inspire scholars of party politics to further explore the evolution of party systems. As such, Green-Pedersen has given us a powerful analytical tool that will have a lasting impact on how we view party-system change in Western Europe and beyond.