Coalition in a Plurality System: Explaining Party System Fragmentation in Britain Jane Green Ed Fieldhouse Chris Prosser University of Manchester Paper prepared for the UC Berkeley British Politics Group election conference, 2nd September 2015. Abstract Electoral system theories expect proportional systems to enhance minor party voting and plurality electoral systems to reduce it. This paper illustrates how the likelihood of coalition government results in incentives to vote for minor parties in the absence of proportional representation. We advance a theory of why expectations of coalition government enhance strategic and sincere voting for minor parties. We demonstrate support for our theory using analyses of vote choices in the 2015 British general election. The findings of this paper are important for electoral system theories. They reveal that so-called proportional electoral system effects may arise, in part, due to the presence of coalition government that so often accompanies proportional representation. The findings also shed light on an important trend in British politics towards the fragmentation of the party system and a marked increase in this tendency in the 2015 British general election. 2 The 2015 general election result saw the Conservative party win a majority of seats in the House of Commons after a period of governing in coalition with the Liberal Democrats. At first glance the result may look like a return to the classic two-party majoritarian government under a plurality electoral system. But this conclusion would be wrong. 2015 represents a high watermark for votes for 'other' parties - those parties challenging the traditional establishment parties in Westminster. Vote shares for UKIP leapt from 3.1% to 12.6%, the Greens from 1.0% to 3.8%, the SNP leapt from 19.9% to 50% in Scotland and Plaid Cymru saw a small increase from 11.3% to 12.1% in Wales. The two-party vote share increased by only 2.2% despite the spectacular collapse of the well establish third party the Liberal Democrats, who lost 15% of the vote. The Conservative majority arose not because of a surge in popular support (the party gained just 0.8% share of the vote) but because of the more successful Conservative transmission of votes into parliamentary seats, compared to Labour. In England the Conservative’s vote gain of 1.4% translated into 21 extra seats, whilst Labour’s 3.6% gain only resulted in 15. Coupled with its collapse in Scotland, this lead to a net loss of 26 seats for Labour, despite increasing its overall vote share by 1.5%. The 2015 British election raises a theoretically important question, namely, what can account for the significant rise in minor party votes in 2015 - votes cast under a plurality electoral system expected to discourage minor party voting? There are many answers to this question that are specific to the issues and competition characterising the period of British electoral history: the apparent ideological convergence of the main parties of government, little differentiation in terms of overall appeal for Labour, the Liberal Democrats or the Conservatives, a strong anti-Westminster sentiment in Scotland as well as in other parts of the UK, and the salience of cross-cutting issues (e.g. immigration). In this paper we diverge from those contemporaneous explanations to offer a theory about the influence of institutions. Namely, we argue that the experience of coalition government - and the expectation of coalition government - altered the incentives of voters in a way akin to the apparent incentives under a proportional representation electoral system. The implication of this argument is that proportional electoral system is not solely responsible for increasing incentives for minor party voting under proportional systems. It is the outcome of proportional system - coalition government - that in part leads to the fragmentation of vote choices spread among a greater number of political parties, not just the transmission of votes to seats. The British case provides a unique test of this theory about incentives under different institutional contexts. It allows variation in the governing system, and perceptions thereof, while holding the electoral system constant, thus moving us towards the ability to isolate these two institutional effects. Anticipating different coalition likelihoods, how a local vote might increase the chances of a desired local and national outcome, knowing which policy combinations different parties may adopt - and whether they would be able to do so, all introduces a great deal of complexity and uncertainty into the vote calculus (Hobolt and Karp 2010). This is likely to be especially complex and uncertain in countries that have recently moved to a proportional system (for example, for Scottish elections to the Scottish parliament, see Carman and Johns 2010) and where coalition combinations are more unpredictable, in closely fought elections or where parties might join coalitions with different ideological alternatives. The 2015 British general election was an extreme case in point. Most Britons had their first experience of coalition in 2010 but were not operating in an electoral system that was thought to make them likely. The election campaign was filled with speculation and uncertainty about the outcome but with a consensus that Labour would be the largest party without an overall majority. There was a significant surge in SNP support in Scotland which led to a late declared denial 3 of a Lab-SNP coalition partnership (which many did not believe) and a greater chance of Labour not winning a majority. There was speculation over the rise of minor parties such as UKIP, and whether that would translate into seats, and a declaration by the Liberal Democrats that they would partner with either major party which had a mandate of the largest number of seats. At the constituency level, unprecedented churn between 2010 and 2015 made normal assumptions of likely winners less predictable. In short, this was a highly complex and uncertain election. We therefore ask, if voters anticipated the hung parliament in 2015, what impact did it have? Our theory of coalition incentives proposes that coalition government increases the incentives to vote in ways typically expected under proportional electoral systems. We outline new reasons in support of this expectation with respect to increasing sincere voting for minor parties, and three reasons with respect to increasing strategic voting for minor parties drawing on the literature on coalition voting considerations within proportional electoral systems. We reveal how those strategic voting expectations relate only to coalitions, not to proportional systems per se. Our sincere voting incentives relate to a reduction in the degree to which a minor party vote is wasted (because a voter may wish to signal greater popular support to bolster its mandate in coalition, and because the party has a greater chance of legislative influence in coalition) and an increase in the degree to which a major party vote (because a major party cannot deliver its full platform, and ideological blurring reduces incentives to vote strategically and increases incentives to vote expressively). The expectation of coalition should not always increase the incentives to vote for minor parties, however. There is one specific context in which existing theory would expect coalition, or its expectation, to turn voters back towards a major party, as predicted by Duverger (1954); classic plurality strategic voting for major parties. It is common in countries where the experience of coalition government is the norm for voters to choose a party within a party bloc; their preferred choice-set. If a voter expects a party to govern with ideologically proximate parties, it makes sense for a voter to choose one of those preferred bloc parties that has the greatest likelihood of winning in their electoral district, or constituency. For some voters this strategic decision will mean a vote for a minor party. But for other voters it will mean a vote for a major party - specifically where a major party has the greatest chance of defeating a less ideologically preferred rival. We currently find no concrete support for this effect in the 2015 British general election, though we do not rule it out. In addition to making an argument about electoral systems and strategic voting, this paper brings a new perspective to bear on the outcome of the 2015 British general election. It suggests that the Conservative party won in spite of coalition-based incentives to vote against the two largest Westminster parties. And as we show in this paper, it won in part because of the contextual dependencies of our theory played out in different constituency contexts. Coalitions in Plurality Systems: How Might Voters Respond? Voter decisions in different electoral systems have been thought to exhibit strategic voting under plurality systems, sincere voting under proportional systems (Duverger 1954; Cox 1997), and latterly strategic voting under proportional systems also, under conditions of low district magnitude, where the transfer of votes is less proportional and hence votes might be wasted, as in plurality systems (Leys 1959; Sartori 1968; Cox and Shugart 1996; Cox 1997). Sincere voting refers to voting simply for one's preferred party, strategic (or tactical) voting to an instrumentally motivated vote choice for a 4 party that has a better chance of influencing government policy than a favoured party (McKelvey and Ordeshook