31
THE GEOMETRY OF PARTY COMPETITION
Introduction: policy issues and the curse of dimensionality
The idea of party competition lies at the heart of even minimal definitions of democracy (Sartori 1976: 63; Schumpeter 1942). Indeed, as we show in this chapter, the geometry of that competition plays a critical role in determining whether democratic politics proves possible in practice. For such competition to function effectively, a necessary starting point is that voters and parties have a common language, one that allows the former to identify which of the latter are most congruent with their ideas and make their choice accordingly. This common language typically centers on the identification of continua or dimensions of conflict (Downs 1957),1 with the left– right divide being the most widely recognized of these (Fuchs and Klingemann 1989). Of course, given the wide range of issues over which political conflict occurs, the reality is a more complex and multidimensional issue space. Multidimensionality as defined here is premised on the understanding that the dimensions in question are largely, if not wholly, unrelated to each other. The position of a voter or party on one issue does not help in predicting their position on another issue. The resultant issue space thus becomes considerably complex (Enelow and Hinich 1984).
Such complexity of course affects voter decision-making and inspired one of the most widely known problems addressed in democratic theory – the paradox of voting. First identified by Condorcet (1785) and then generalized by Arrow (1951) as the impossibility theorem, the core of the paradox is that rational (i.e., transitive) individual preference rankings of more than two policy alternatives, when aggregated according to majority rule, may lead to irrational (i.e., intransitive) and unstable collective preference rankings. While Arrow ultimately concluded that a stable preference ranking was incompatible with democratic rules, Black (1948) persisted to reveal that the paradox originated in the multidimensionality of the issue space. When individual preferences align on a single dimension, he argued, the paradox dissolves and a Condorcetwinner alternative emerges.2 Majority rule under such conditions can produce a single outcome – the position espoused by the median voter – that beats all alternatives. Democracy in effect now becomes possible.
This more singular understanding of party competition anchored many of the theoretical debates and empirical approaches to understanding developments in party systems over several decades following the Second World War. Its resilience has come under increasing challenge, however, in the face of the new parties and new issue dimensions that emerged in more recent decades. Such developments have required adoption of a more innovative and flexible framework that can accommodate the growing spatial complexity of political conflict. In particular, we need a new approach that can combine conceptual speculation with a workable empirical model permitting systematic analysis and theory testing. In the final section of the chapter, we outline the “issue yield” theory as one of the more promising attempts to fill this gap.
The evolving geometry of Western European party systems: conflict in a uni-dimensional space
According to the classic work of Lipset and Rokkan (1967), modern democratic states emerged in West European countries after a process of consolidation and reduction in the lines of political conflict. Indeed such was the level of consolidation that occurred, the period from the 1920s until the 1970s were widely seen as dominated by a small set of social cleavages that coalesced ultimately around the class divide. This singularity was further reflected in a consistent model of electoral competition that emerged over time in many of these countries whereby government switched hands between two main parties (or party blocs).3 These historical developments appeared increasingly compatible with the assumption of uni-dimensionality in political conflict that was a cornerstone of Downs’ (1957) highly influential work An Economic Theory of Democracy. Under such an assumption, both voters and parties agree on the absorption of a multiplicity of issues into one single dimension – the left–right dimension. This then allows for a “proper” theory of democracy to emerge whereby rational voters facing two vote-seeking dominant parties (or blocs) will produce a Condorcet-winning Nash equilibrium, corresponding to the position espoused by the median voter.
Despite the limitations of Downs’ median voter theorem in terms of its restriction to a onedimensional space, it did prove a formidable step in the development of a general theory of political equilibrium. Furthermore, in practical terms, its ability to show that representative democracy could produce a political equilibrium that represented the will of the people was important, in an age where liberal democracy was clearly not the only viable model of political regime. Within political science, the Downsian framework continued to be widely used as a tool for understanding the behavior of parties and voters in the decades that followed. Indeed its influence can be traced, somewhat paradoxically, to the development of one of the main theoretical approaches for understanding parties’ emphases on multiple policy issues – salience theory (Robertson 1976; Budge and Farlie 1983). According to this logic, parties engage in political competition by adopting a selective emphasis strategy. This means that rather than taking explicit positions on most issues, they focus disproportionately on a particular subset that can act as a proxy for their overall political platform. This history of attention to, and credibility for, certain issues means that parties become in effect the “owners” of those issues and the main beneficiaries of a rise in their salience. The link back to Downsian theory is not immediately apparent but becomes more so when we realize that the practice of selective emphasis is in effect a means for parties to signal to the electorate their location on a broader continuum of ideological conflict.4 A common example of this type of signaling can be seen in parties’ position-taking vis à vis economic policy and particularly the classic tax and welfare trade-off. Social-democratic parties focus almost exclusively on the desirability of welfare provisions while avoiding the necessary implication of higher taxes. Conservative parties, by contrast, advertise tax cuts and hide the implied reduction of welfare. Here we see how a selective issue emphasis serves as a means for parties to communicate their position in broader left–right terms.
Such was the success and appeal of salience theory as a means of interpreting parties’ policy positions that it led to the founding of one of the flagship studies of post-war comparative politics – the Manifesto Project. By measuring the variation in the emphasis given by parties to specific policies during election campaigns it became possible to track their spatial location across the left–right continuum over time (Budge 2015). These cumulative data could then provide a means for assessing the capacity of the party system to successfully represent the views of the median voter, and thus ultimately its capacity to produce desirable democratic outcomes, in line with Downsian theory.
The preceding accounts take a largely consensual and functional view of the institutions and actors necessary to democratic, legitimate decision-making. A limited range of parties arrayed across a single dimension of conflict essentially makes a political equilibrium possible, thereby justifying the preservation of such procedures and competition patterns. A party which emerges to focus on new non-aligned issues could thus potentially be regarded as a threat given that it would reduce the chances for political equilibrium and ultimately the efficient functioning of a democratic system. As one might imagine, however, an alternative perspective on issues and party competition has subsequently emerged that accommodates a more multidimensional and conflictual political reality. According to this viewpoint, political conflict and resolution is better understood as a series of temporary equilibria or settlements that are likely to change again in the future, as the balance of power changes between actors. According to such a perspective, a party engaging in mobilizing around new disruptive issues can be seen as the rational exploitation of strategic tools by actors that are losing in the current equilibrium.
Breaking the game: multidimensionality and the rise of issue voting
The idea that a multiplicity of issues could be seen as a strategic resource, especially for parties attempting to escape an unfavorable competition context, presented a clear challenge to the Downsian state of political equilibrium. The earliest systematic articulation of this idea emerged in Stokes’ seminal work on valence politics (Stokes 1963). Inspired by the successful Eisenhower campaign of 1952, Stokes identified a critical turning point in the election when the Republican nominee turned disadvantage into a landslide victory. This pivoted on the realization by the Eisenhower campaign that voters were not tied to the left–right distinction and that victory in fact lay in “exploiting relatively new and transitory political attitudes” across a wide range of non-partisan issues such as Korea, corruption and communism on which the candidate had significant credibility (Stokes 1963: 372). The key insight of Stokes’ work relevant to discussion here5 is that a party facing an unfavorable equilibrium would emphasize alternative issues in order to shift the attention of the public. This was important in that it introduced to the literature the idea of issue emphasis as a strategic resource.
Rather surprisingly, this understanding of issues as strategic tools for party competition lay dormant for a long period of time. Riker’s introduction of heresthetics constituted the first attempt to develop it theoretically to understand political outcomes (Riker 1986). According to Riker, the intransitivity-related disequilibria produced by multidimensionality – while detrimental to democracy in the long term – should realistically be seen as a resource for political actors to escape an unfavorable equilibrium. Or stated in more practical and individual terms, “For a person who expects to lose on some decision, the fundamental heresthetical device is to divide the majority with a new alternative, one the person prefers to the alternative previously expected to win” (Riker 1986: 1). This strategy captures entirely the Eisenhower logic of 1952. According to Riker, a heresthetic strategy deliberately exploits multidimensionality in order to successfully subvert what – under uni-dimensionality – would be considered as a stable Nash equilibrium.
As well as more effectively capturing the complexity of political competition in a liberal democracy, the new approach can be seen as taking an alternative and rather less idealized view of citizen decision-making. In rejecting the idea of a political equilibrium, it follows that voters do not formulate electoral choices primarily on stable ideological criteria but are influenced by more transient issues. While such an assumption arguably resonated among the US electorate as early as the 1950s, it was some decades before it was regarded as applying to the voters of West European nations. As the frozen cleavages identified by Lipset and Rokkan (1967) underpinning the party systems of the region began to unfreeze, however, the relevance of valence politics and theories of issue voting assumed an increasingly important role for scholars of electoral behavior.
From issue voting to issue politics
Although scholars remain divided over the key drivers of the decline in cleavage politics (Evans and Tilley 2012), general agreement exists that from the 1970s onward most West European countries have seen a decrease in the importance of the social determinants of vote choice and a corresponding growth in levels of electoral volatility and issue voting (Franklin, Mackie and Valen 1992; Mair 2002; Knutsen 2004; Thomassen 2005; Aardal and van Wijnen 2005). A comparative interpretation of this process has framed it in terms of changes in the political context of party choice. In particular, Thomassen (2005) has related the two key competing drivers of cleavage decline – party dealignment and individualization of vote choice – to the increasing innovation in party strategy and push toward a catch-all, ideology-lite orientation. Recent empirical research has shown support for the idea of decreasing ideological differentiation between parties (Adams, de Vries and Leiter 2012; Adams, Green and Milazzo 2012; Hellwig 2014).6 In such a context, issues acquire more importance not only in voters’ decision processes, but also in party strategy. If ideological differentiation loses its distinctive ability, it is not surprising that parties will attempt to identify new dimensions of competition.
A first possibility is of course to shift the focus toward valence issues. Manin’s (1997) theory of audience democracy corresponds well to such a strategy. Here party competition hinges largely on the credibility of political actors to achieve shared goals for the polity as a whole.7 A wide range of empirical studies have supported the idea of such a shift, demonstrating how party competition has moved toward issue emphasis and competence rather than positionally-based conflict (Nadeau et al. 2001; Blais et al. 2004; van der Brug 2004; Clarke et al. 2004, 2009; Bellucci 2006; Bélanger and Meguid 2008; Duch and Stevenson 2008; Green and Hobolt 2008; Sanders et al. 2011).8
A second possibility, more in tune with Riker’s understanding of heresthetics, is that parties can seek to selectively focus on specific positional issues. While such a response is in theory open to all parties, it is likely to be particularly appealing to those parties for whom a valence strategy is unrealistic if not impossible – that is, the smaller, more radical players who lack government experience and/or have little chance of entering government. Again empirical evidence has served to confirm the validity of this approach. Green-Pedersen (2007), for example, has documented a continuous decline in the left–right content of election manifestos as parties take on a wider variety of policy issues. At the same time, we have seen the rise of a range of smaller parties mobilized around key issues such as the environment (O’Neill 1997; Mair 2001; Talshir 2002), immigration (Betz 1994; Kitschelt 1995; Hainsworth 2000), and more recently EU integration (de Vries and Hobolt 2012). Indeed such has been the proliferation of these new actors that the new labels of “niche” (Meguid 2005, 2008; Adams et al. 2006; Ezrow 2008) and “challenger” (de Vries and Hobolt 2012) parties have now been added to the lexicon of party types.9
The growth in importance of issues in structuring party competition and vote choice means that it is now more accurate to talk about issue politics in general rather than specific instances of issue voting. As this review has shown, there have been considerable advances on theoretical grounds with regard to understanding how and why parties manipulate issue emphasis for electoral gain. In addition, the empirical literature has clearly demonstrated the value and importance of an issue-oriented party strategy. What is needed now, however, is to develop a new framework that can trace back the dynamics of strategic issue selection – that is, the logical step that precedes the selective issue emphasis by parties in a multidimensional space. Furthermore, it should be one that is potentially applicable across all issues and all parties, rather than reserved to a specific subset. We move now in our final section to outline one of the most promising candidates in this regard – issue yield theory.
Issue yield theory
Issue yield theory is an adaptation of Downsian logic and centers on four key assumptions:
a Party strategy is driven by vote maximization.
b Voters evaluate parties in Downsian terms – that is, voter–party proximity calculations.
c Contrary to Downs, however, change in a party’s issue position is more difficult and costly than a change in issue emphasis.
d The importance that voters assign to issues varies and is sensitive to priming effects – that is, the emphasis placed on issues by parties.
Should these assumptions be met, then parties are incentivized to pursue a strategic issue emphasis strategy. That is, they will seek to focus on a limited number of favorable issues which they prime in the minds of voters as the core criteria to rely on in making their party choice.
The challenge that parties face in adopting this approach, therefore, is to identify their most favorable issues. The issue yield model stipulates that such issues are those that meet the two following conditions: first, the policy attracts the lowest amount of internal division possible and, second, the policy is widely supported in the electorate at large – that is, beyond the current support base. This combination of low risk and high opportunity both minimizes the potential for loss of existing support and expands the opportunity to gain new voters. The combination can be expressed in numerical terms through an issue yield index (constructed from public opinion data on policy and party support) that ranges – for each party-issue combination – from –1 (worst issues) to +1 (best issues).10 Policies that provide the best combination of these two desirable properties – that is, a united party base and the potential to reach out to a larger electorate – have the highest issue yields. In theoretical terms, those with the highest issue yield can be regarded as forming a new type of “bridge” policy, so named because they create a bridge between current and new voters. Bridge policies essentially unify current voters by staying in line with the party ideology, while extending its appeal to new voters.11
While such issues can be articulated in theory, the key question of course is whether they exist in practice. Empirical research on EU countries and also the US (De Sio 2010; De Sio, De Angelis and Emanuele 2016; De Sio and Weber 2014; Weber and De Sio 2016) has consistently shown that almost all parties rely on a set of high-yield bridge issues where the party position is almost unanimously supported within the party and also widely shared outside the party. Such a combination makes the issue a powerful resource for gaining new voters. Examples range from financial market reform for the US Democratic Party (support of 92 percent within the party and 77 percent at large, with a yield of 0.88) and opposition to tighter gun control for the US Republican Party (84 percent within the party, 56 percent at large, yield = 0.78), to more restrictive laws on immigration for the Italian Northern League (95 percent within-party, 78 percent at large, yield = 0.95) and finally reduction of income inequality for the Italian PD (91 percent within-party, 84 percent at large, yield = 0.85).12 While each issue presents a different risk– opportunity combination for each party, it is clear that any party enjoys at least a small number of high yield issues. The inevitable theoretical expectation is that parties will disproportionately focus on making these high-yield bridge policies salient in voters’ minds during election campaigns in order to gain electoral advantage.13
This last point has also been consistently supported by empirical research, which has tested a number of causal implications of the issue yield model. In particular, scholars have shown the yield index to work at the individual level in predicting issue preference among supporters of different parties (De Sio 2010). It has also worked at the party level, explaining issue emphasis in campaign platforms in EU countries and the US (De Sio and Weber 2014; Weber and De Sio 2016), and the dynamics of issue of competition over EU integration after the economic crisis (De Sio, Franklin and Weber 2016). Perhaps most innovatively, a subsequent analysis of the Italian case has shown how issue yield predicts the content of parties’ and their leaders’ official Twitter feeds during the campaign (De Sio, De Angelis and Emanuele 2016). Significantly, all of these studies have found no interaction effects for party size.14 As such, it would seem to offer a highly resilient and effective new approach to understanding the complexities of issue selection by political parties in a multidimensional environment and thus an important step toward filling the theoretical gap outlined earlier.
Viewed in historical context, the issue yield model appears to fit more within the Rikerian than Downsian tradition of understanding party competition. There is no attempt to demonstrate the presence of equilibria. The emphasis is instead upon how the disequilibria resulting from conflict in a multidimensional space can be used to subvert an existing equilibrium.15 This should not be seen as supporting a view that parties pursue short-sighted, short-term strategies. On the contrary, party strategy is very firmly anchored in the past in that the existing party base provides the final reference point for choosing which policies can be exploited and which cannot. The model thus predicts an incremental evolution of party platforms and support base over time rather than swift change.16
Concluding remarks
The idea that the political issue space has become increasingly multidimensional and conflictual over the past few decades appears to be widely accepted among parties and election scholars. One consequence of this process is that models of party competition based on a reduction in the dimensionality of the issue space, in order to achieve efficient and legitimate decision-making, have come under increasing pressure. In their place, more flexible theories have emerged that see the growing multiplicity of issues as a resource for disadvantaged actors to use in a bid to escape an unfavorable equilibrium. One of the strongest contenders in this regard, we have argued, is issue yield theory, which presents a more general explanatory framework of party behavior in this new era of issue politics and increasing specificity of vote choice. In terms of its longer term applicability, it is clear that if current trends continue and even intensify then we would expect the issue yield model to increase in value as a means of accounting for party policy choices. Should the current state of volatility subside, however, in favor of a resurgence of the type of stable voter–party alignments associated with past cleavages, we do not expect issue yield’s relevance to entirely fade from view. Parties will continue to face strategic challenges on whether and how to integrate different issues into their platforms. Which of these two scenarios is most likely to occur, however, is the task of other chapters in this volume to address.
Notes
1This spatial representation of politics does not require any market analogy.
2Black’s result was then incorporated into the second edition (1963) of Arrow’s Social Choice and Individual Values (Grofman 2004).
3An additional source of tension toward a one-dimensional scheme is also clear from the structure of alliances and coalitions reconstructed in detail by Lipset and Rokkan (1967: 37), where it clearly appears that actors defined by different cleavages tend to coalesce in supporting (or opposing) the nationalizing elite group. In this regard, it is the very mechanism of majority rule that pushes political conflict toward a one-dimensional scheme (see, for example, Duverger 1964). Also, the reduction of the complexity of the issue space to a very low number of dimensions might be considered an inevitable development of the party system in order to present voters with more manageable cognitive tasks (Jackman and Sniderman 2002; Sniderman and Bullock 2004). The special relevance of the left–right dimension among Western European voters might be indeed confirmed by their enduring ability to place themselves on the left–right continuum (Knutsen 1995, 1997) despite the repeated claims of its death (Giddens 1994).
4And one that allows researchers to conveniently measure such location.
5While we extract this aspect of Stokes’ work to develop the key point of interest in this chapter, it should be noted that the main contribution of the article in question was the introduction of the valence politics framework. See, for example, Keith Dowding’s chapter in this volume for further discussion of valence theory.
6Hellwig (2014) argues that the importance of the left–right dimension has decreased as a result of a clear perception (shared by elites and voters) of a narrowing of the credible range of possible policies on the economic issues that constitute the core of the left/right divide.
7Also, Manin’s original formulation (visibly inspired from François Mitterrand’s first mandate) explicitly related audience democracy to the presence of an international context with a high level of interdependence (thus limiting the available spectrum of policies, especially on the economy), and where the protection of shared national interests becomes crucial.
8In fact, a large part of the economic voting literature, with special regard to retrospective voting (Fiorina 1981), can be considered as adopting a valence framework (Stokes 1992: 156). On valence vs. positional perspectives in economic voting, see e.g., Lewis-Beck and Nadeau (2011).
9Although the operational definition of a niche party is far from uncontroversial, and it can be claimed that the niche attribute might be more appropriate for the party platform than for the party itself (Wagner 2011).
10Calculated according to a non-linear formula derived through geometric reasoning (see De Sio and Weber 2014). If: p is the percentage of respondents supporting a party; i the percentage approving a policy statement; f the percentage jointly supporting the party and approving the statement; then issue yield is expressed by 
.
11Such policies, enjoying a high level of popular support, can be considered quasi-valence issues (De Sio and Weber 2014), albeit without the volatility of credibility reputations that make “pure” valence issues somehow risky.
12Sources: CCES 2010 for the US, CISE (Italian Centre for Electoral Studies, 2014) for Italy.
13Of course parties cannot be expected to use tools such as issue yield in their campaign calculations (although issue yield might perhaps be used as a tool for testing the potential of new issues); simply, the issue yield model attempts to systematize a typical intuitive reasoning that can be expected from party strategists. Also, in multi-party systems parties can be expected to consider additional concerns, i.e., whether an issue with a high yield might have a higher yield for another party, so that emphasizing it would in fact advantage a competitor. In this case a party might perhaps emphasize another issue – even with a lower yield – where it can claim some sort of yield “monopoly.” Various approaches have been proposed to model such a strategy (De Sio and Weber 2014; De Sio, De Angelis and Emanuele 2016).
14Despite its size insensitivity, the issue yield model does carry an expectation that smaller parties will have stronger incentives to pursue issue politics compared to their larger counterparts. One of the key resources offered by a high yield issue is the ability to expand beyond the current support base. Thus in statistical terms there will be a larger number of such issues for parties sitting on 10 percent of the vote compared with those gaining a 35 percent vote share.
15This resonates with the recent success of many “anti-establishment” parties in challenging the electoral primacy of mainstream parties, by relying on new issues.
16This process resonates with the integration of “new politics” issues by mainstream leftist parties during the 1980s. Another example is the impact of post-crisis measures (with a drop in EU integration support), which impacted very asymmetrically pro- and anti-EU parties, resulting in important new opportunities for anti-EU parties (De Sio, Franklin and Weber 2016).
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