Political fragmentation is the division of the political landscape into so many different parties and groups that the governance might become inefficient.^[1] Political fragmentation can apply to political parties, political groups or otherpolitical organisations. It is most oftenoperationalized using theeffective number of parliamentary parties.^[2]

Scholars, journalists, and politicians have theorized about a number of potential effects of political fragmentation. For example, it has been argued that higher fragmentation allows voters to better represent theirpolitical spectrum of political positions. The length of government coalition formation has also been argued to increase with number of parties and decreases with preexistingpolitical groups.^[3] The strength of these effects has been hypothesized to depend on whether it is the government or the opposition that are fragmented.^[4] However, the political fragmentation of parliaments has little causal effect on a number of dimensions of the quality of democracy.^[5] Theveto player theory predicts that higher fragmentation relates togridlock,^[6] but other literature does not observe increased gridlock.^[7]

Whileone-party states areauthoritarian,dominant-party systems can be democratic.^[8]

The political fragmentation, represented by effective number of parties, is roughly estimated with theseat product model,^[9][10] and increases with district magnitude and assembly size. The political fragmentation tends to move towards an equilibrium, depending on the voting system.^[11]Duverger's law predicts majoritarian elections withdistrict magnitude of one favor a two-party system andproportional representation increases the number of parties. In proportional representation, higher electoral thresholds tend to reduce the number of parties since voters voting for smaller parties have a higher risk of having theirvotes wasted.^[12]

Strong autocrats can prefer a fragmented political system, while weaker autocrats can prefer a low level of party fragmentation.^[13]

• Pildes, Richard H. (2022)."Political Fragmentation and the Decline of Effective Government". In Jackson, V.C.; Dawood, Y. (eds.).Constitutionalism and a Right to Effective Government. Comparative Constitutional Law and Policy.Cambridge University Press. pp. 235–246.doi:10.2139/ssrn.3868421.SSRN 3868421.

• Voting theory

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