Editor's Note

Since democratization, South Korean party politics has been featured by increasing party polarization and incomplete party sorting. In this issue briefing, Prof. Jung Kim examines several factors that have led to party polarization and incomplete party sorting in the country’s politics. Prof. Kim argues that under the two-and-a-half party system, political representation has been unequal, as it over-represents progressive and conservative voters while under-representing centrists, thereby increasing polarization between progressive and conservative parties. At the same time, Prof. Kim argues that the number of centrist voters who do not fall under the ideological distributions of the major parties remains significant, which indicates that party polarization has not been corresponding with party sorting, leaving centrist voters in drift.

This essay seeks to illustrate party politics in South Korea that has unfolded since its democratic transition that took place in 1987. For starters, it argues that South Korea’s party system has brought about an asymmetric structure of political representation that over-represents progressive and conservative voters while under-representing centrist voters. It also claims that unequal political representation has engendered party polarization in South Korean politics. It further argues that party sorting has been incomplete whereby parties have difficulty shaping political issues in a partisan way to exploit their electoral advantages. Increasing party polarization and incomplete party sorting capture the evolving nature of party politics in South Korea since its democratic transition. 

Asymmetric Political Representation

South Korea’s party politics has been gradually stabilized since its democratic transition, producing a two-and-a-half party system. The average number of legislative parties has changed from 2.77 in the 1990s to 2.63 in the 2000s, and 2.41 in the 2010s This two-and-a-half party system consists of ‘two’ parties that have managed to maintain the continuity of partisan brands as progressive and conservative respectively, and ‘half’ parties that have inevitably faced the interruption of partisan brand as centrist. Progressives have altered their party labels from Peace Democratic Party (1987-1991) to Democratic Party (1991-1995), National Congress for New Politics (1995-2000), Millennium Democratic Party (2000-2005), Uri Party (2003-2007), Unified Democratic Party (2007-2011), Democratic Unified Party (2011-2014), and Democratic Party (since 2014). Likewise, party labels for conservatives have changed from Liberal Democratic Party (1990-1995) to New Korea Party (1995-1997), Grand Korea Party (1997-2012), Saenuri Party (2012-2017), Liberty Korea Party (2017-2020), and United Future Party (Since 2020). Despite recurrent relabeling, South Korea’s progressive and conservative voters have acknowledged the succession of partisan brands from one party to another, attaching their partisan loyalty, however tenuous it might be, to the ‘two’ parties. 

For South Korea’s centrist voters, no such continuity of partisan brand has been established from United People’s Party (1992-1995) to United Liberal Democrats (1995-2006), Creative Korea Party (2007-2012), People’s Party (2016-2018), and Bareun Party (2017-2018), simply because these parties were not successor parties one another.  Consequently, centrist voters have found themselves in a situation in which their efforts to attach partisan loyalty to centrist parties are destined to be interrupted. The National Assembly members are selected by the majoritarian mixed-member electoral system consisting of 85% of seats from single-member districts and 15% from proportional representation lists, which institutionally favors two larger parties at the cost of smaller parties. Under such a ‘winner-take-all’ systemic pressure, centrist voters, which consist of more than 40% of the electorate, according to a recent opinion survey, tend to abstain or to be compelled to cast their ballots for one of the larger parties in order not to waste their votes. Centrist voters with the weak partisan attachment are less likely to have strong incentive to engage in political life. In fact, a study shows that voters with strong partisan identities are more likely to vote than voters with weak partisan identities during recent presidential elections in South Korea. 

In sum, South Korea’s two-and-a-half party system has brought about an asymmetric political representation, in which voters with strong partisanship tend to be over-represented, while voters with weak partisanship tend to be under-represented. This is why political scientist Jang Jip Choi claims that the “greatest cleavage in contemporary Korean politics is between a representation system with no social foundation and the nonvoters who resist and cannot gain representation through that system.” 

Increasing Party Polarization

The asymmetric structure of political representation, in which progressive and conservative voters are more actively involved in politics in general and elections in particular than centrist voters are, has made electoral strategies of two large parties depart from the median voter theorem and resort to strategic extremism. To put it differently, the two large parties are more likely to rely on ‘mobilization’ to push for voters with strong partisan identities who will vote for them to go to the polls rather than ‘persuasion’ to convince voters with weak partisan identities who are more predisposed against, but not adamantly opposed to, them to change their opinion. Once the two parties decide to abjure ‘persuasion’ and to embrace ‘mobilization’ as their dominant electoral strategy, then party polarization would kick in. Figure 1 demonstrates this logic of party polarization with the disappearing centrists.