This chapter provides an analytical framework for the empirical studies comprised in the volume. It starts by defining the relevant temporalities to study party strategies and sociostructural processes of electoral realignment. The chapter then develops the concept of the “social democratic idea” that underlies the entire left field of political parties. The third section defines four key structural challenges to the social democratic idea and the potential responses and trade-offs resulting from them for the left field. The fourth section discusses party strategic alternatives to respond to structural challenges and transformations of the social democratic electorate and then differentiates this discussion by different contexts characterized by political-economic legacies and institutions. The chapter concludes with an outline of the book.

The concluding chapter first provides a brief summary of the main findings reported in the multiple complementary investigations on which this book reports. The second task of the conclusion to this volume is to address influential alternative accounts that have attracted considerable scholarly attention and to discuss them considering the cumulative empirical evidence we have presented throughout this book. On the one hand, rival accounts challenge that there is any durable structure of voter-party alignments left in contemporary party systems and democratic polities have entered a world of fluidity, in which the tactical moves of – (social) media enabled – political entrepreneurs are what really counts. On the other hand, a different tier of rival accounts sees not partisan dealignment and the fluidity of media democracy as the problem of traditional left-wing parties, but the failure of social democratic parties to act on the disempowerment of wage earners by capitalist business interests whose leverage has been magnified through globalization of the movement of goods, services, people, and capital. In the very brief third and final section of this book, we posit that the partisan realignments of the past generation on which we report in this volume may not generate a durable equilibrium of party competition. In the twenty-first century, party politicians may be able to map still a subset of novel upcoming emerging policy issues on the existing dimensions of partisan alignment. But there may be profound political challenges in the offing that could disorganize existing party systems fundamentally.

Why do voters accede to or abandon social democratic parties in the most recent decades? This chapter analyzes the reasons that motivate voters go choose among parties. Are spatial considerations coming into play, that is, do voters move to parties that are more consistent with their preferences than those they abandon? This chapter tests this argument with European Election Study data from 1999 to 2019 focusing on those respondents who report a different party preference at the time of a survey compared to their past vote recall (“vote switchers”). The data reveal a robust relationship between switching direction and voter preferences, bearing out rational spatial theories of voting. For Social Democrats’ strategy considerations, however, this brings to light an inconvenient fact: Voters abandon their parties for very different reasons heading to a plurality of alternatives. Consequently, no unified party strategy can stop the vote hemorrhage on all fronts of competition.

This chapter focuses on the electoral performance of social democratic parties in different institutional and competitive contexts. We explore three avenues to shed light on the relationship between social democratic parties’ strategic interaction with competitors and their respective electoral payoffs. We start from premises of spatial theories of party competition but hypothesize only behavioral relations between party choices and electoral outcomes, not strategic equilibrium configurations. We ask three questions: first, holding all other parties’ positions constant, do party positions closer to the center of a policy dimension – where empirically most voters are located – pay off in electoral terms and does this effect vary across relevant dimension of party competition? Second, does distance of parties from competitors improve their electoral fortunes? Taking spatial considerations of the first two questions together, are parties electorally better off if they place themselves closer to the center of policy spaces, while simultaneously facing only distant competitors? Third, what are the electoral consequences of two focal parties – a moderate left (social democratic) and a moderate right (conservative or Christian Democratic or People’s) party – simultaneously choosing positions in a multiparty field? These consequences may be different for the individual parties and for their ideological “field.” The performance of individual parties turns out to be much in line with spatial theory: When Social Democrats move to the center, they are likely to win voters from the center-right, but lose votes to green-left and radical-left parties within the left field. Social Democrats often perform stronger when they move left than to the center. But there is a crucial difference between their choices when it comes to considering the electoral performance of the entire set of left-field parties. By moving to the center, and shedding votes to their leftist competitors, Social Democrats sometimes effectively increase the size of the leftist field and thereby also boost their own bargaining power over coalition governments, as they are usually the most moderate party in the left field and most capable of crafting coalitions with parties of the center-right, particularly if Social Democrats control the median voter.

The relationship between social democratic parties and labor unions is of interest for the entire era of labor mobilization since the nineteenth century. The middle-class shift in the employment structure of West European countries, the emergence of second-dimension politics, and the pluralization and fragmentation of the “left field” raise several questions in this regard: Have the constituencies of left parties and trade unions developed in parallel or they diverged? Consequently, do the average preferences of trade union members and left voters align or diverge? Do unionized left voters sort increasingly into radical left, social democratic or green and left-libertarian parties?

In this chapter, we address the subject of union–party relations and how it relates to social democratic fortunes with microlevel data on membership, political preference profiles, and electoral behavior. We find that the bond between labor unionists and social democrats is anchored in a rather close similarity and convergence of policy preferences. This proximity of beliefs is not limited to questions of economic redistribution but also covers policy issues concerning societal governance and immigration. In many instances, unionists are – on average – more libertarian on questions pertaining to the dimension of societal governance and more inclusive and universalistic on questions of citizenship than nonunionized social democratic voters. In consequence, unionists are progressively less an uncontested electoral preserve of Social Democracy.