Competitive party systems can be defined in two ways. They may be defined as all party systems in democratic countries, where competition among parties is at least theoretically possible. Alternatively, they may include only those party systems in which elections involving actual competition among two or more parties routinely takes place. For the sake of a broader focus of competitive party systems, the alternative definition is more encompassing and defined further in this entry. Competitive party systems differ from one-party systems primarily in terms of the number of parties that are able to seriously compete for power during elections. In one-party systems, a single dominant party routinely wins elections by a wide margin while all other parties receive quite small vote shares. In competitive party systems, by contrast, two or more parties generally receive substantial numbers of votes during elections. Hence, there is the possibility of alternation in power, in which the party that governs the country at the point of the election loses to an opposition party.
Because one or more opposition parties can meaningfully threaten the governing party with removal from power, elections in competitive party systems can serve as contests among various visions for the future of the country. Anthony Downs, in An Economic Theory of Democracy (1957), showed that, under certain conditions, the competitive nature of elections causes party systems to become extremely responsive to the ideological and policy desires of the electorate. If elections are decided primarily on the basis of parties’ alternative platforms and proposals, then, competitive party systems may outperform one-party systems in terms of representation.
Elections in one-party systems are often thought to be characterized by patronage politics; that is, gifts of goods or services from the political party to voters. However, patronage politics play an important role in competitive party systems, as well; parties may use patronage to win voters who prefer another party’s ideology or policy proposals. At the extreme, elections can become a contest to see which party can offer more patronage to a larger number of voters, with ideology and policy issues entirely neglected. Hence, patronage threatens to undermine the advantage that competitive party systems have over one-party systems in terms of representation.
The majority of party systems in democratic countries throughout the world are competitive rather than one-party systems. Democratic one-party systems have proven viable for long periods of time in several countries, such as Japan, Botswana, and Sweden. In other countries, such as Mexico and Singapore, maintenance of a one-party system depended on the ability of the government to impose restrictions on democracy. However, most party systems in democratic Europe and in the Western Hemisphere have been competitive, as have the party systems of some democratic countries in other regions.
KINDS OF COMPETITIVE PARTY SYSTEMS
The most common approach to differentiating among kinds of competitive party systems is to distinguish by the number of parties that have a meaningful chance of winning elections. By definition, competitive party systems contain at least two important parties, but they sometimes have many more. Hence, the simplest distinction to make is between two-party and multi-party systems. Giovanni Sartori’s Parties and Party Systems (1976) extends this typology, dividing multiparty systems into limited pluralist systems with three to five important parties and extreme pluralist systems with more than five significant parties. Two-party and limited-pluralist systems lead political parties to moderate their ideologies and policy proposals in order to win the support of centrist voters during elections. Extreme pluralist systems, by contrast, are said to encourage parties to radicalize their proposals in order to differentiate themselves from the many competitors within the party system.
Since the publication of Sartori’s work, discussion has focused on a quantitative classification of the number of effective parties in a competitive party system, typically denoted as N. Because N is a continuous measure of the number of meaningful parties in a system, it allows precise descriptions of differences in party systems across countries and over time. If Si represents the vote share of the ith party in a given election, the formula for N in that election is:
Other analysts have proposed that competitive party systems be distinguished according to their degree of insti-tutionalization. A highly institutionalized party system is one in which the same set of specific political parties persists across elections, the parties have well-developed organizational and psychological connections to the electorate, and party leadership succession is handled by well-specified intra-party procedures. By contrast, a weakly institutionalized party system consists of parties that appear and disappear as organizations on a relatively regular basis; parties form only weak, temporary ties with voters; and party leadership is intensively concentrated in specific individuals, creating a major party crisis each time that a new leader is needed. Most party systems in developed countries are relatively institutionalized, whereas many party systems in less-developed countries and in the post-Soviet world are more weakly institutionalized.
CAUSES OF DIFFERENCES IN PARTY SYSTEMS
What factors determine the kind of competitive party system that a democratic country will have? Scholars have offered two major explanations of observed divergences in the number of parties within a party system: the number of major divisions within society, and electoral rules.
In their essay "Cleavage Structures, Party Systems, and Voter Alignments: An Introduction" (1967), Seymour Martin Lipset and Stein Rokkan argued that European party systems have been profoundly shaped by the resolution that each society has found to a series of shared challenges, each of which encourages a new segment of voters to form a lasting attachment to some specific political party. For example, if the society resolves debates over the proper relationship between church and state early on by allowing religious liberty, then the party system is likely to lack political parties based on divides among religious denominations. If, however, state sponsorship of one particular church persists, then political parties may be expected to form along religious divisions in order to either contest or protect the established church’s privileges. A major implication of this idea is that societies with a larger number of major social divisions will have more political parties than societies that are divided along fewer important social lines.
Maurice Duverger’s Political Parties, Their Organization and Activity in the Modern State (1954) explains differences in the number of political parties within a competitive party system in terms of electoral rules. He argues that electoral systems in which only one candidate per electoral district can win produce two-party systems. On the other hand, electoral systems that allow multiple winners per district result in multi-party systems. Hence, decisions about electoral rules are one of the major tools that societies have for managing the kind of competition that emerges among parties within a party system.
To date, no meaningful consensus has emerged about the factors that cause party systems to become institutionalized. Scholars have argued that greater length of democratic experience and higher levels of economic prosperity may encourage the institutionalization of competitive party systems, but these arguments are understood to be at best partial explanations of the phenomenon of institutionalization among competitive party systems.