Editing Political party (section)

===Individual and group incentives===
[[File:The Ideals of United Australia (cropped).jpg|thumb|upright=0.75|It is easier for voters to evaluate one simple list of policies for each party, like this platform for the [[United Australia Party]], than to individually judge every single candidate.]]
An alternative explanation for why parties are ubiquitous across the world is that the formation of parties provides [[Incentive compatibility|compatible incentives]] for candidates and legislators. For example, the existence of political parties might coordinate candidates across geographic districts, so that a candidate in one electoral district has an incentive to assist a similar candidate in a different district.<ref name = "Aldrich95">{{cite book | last1=Aldrich | first1=John | title = Why Parties?: The Origin and Transformation of Political Parties in America |chapter=1 | publisher = University of Chicago Press | year = 1995}}</ref> Thus, political parties can be mechanisms for preventing candidates with similar goals from acting to each other's detriment when campaigning or governing.<ref name = "Hicken09">{{cite book | last=Hicken | first=Allen | title = Building party systems in developing democracies |page=5 | publisher = Cambridge University Press | year = 2009}}</ref> This might help explain the ubiquity of parties: if a group of candidates form a party and are harming each other less, they may perform better over the long run than [[Independent politician|unaffiliated politicians]], so politicians with party affiliations will out-compete politicians without parties.<ref name="Aldrich95"/>

Parties can also align their member's incentives when those members are in a legislature.<ref name = "Cox99">{{cite book | last1=Cox | first1=Gary | last2 = Nubbins | first2 = Mathew | title = Legislative leviathan | publisher = University of California Press |page=10 | year = 1999}}</ref> The existence of a party apparatus can help coalitions of electors to agree on ideal policy choices,<ref>{{cite journal | last = Tsebelis | first = George | title = Veto players and institutional analysis | journal = Governance | volume = 13 | issue = 4 | pages = 441–474 | year = 2000| doi = 10.1111/0952-1895.00141 }}</ref> whereas a legislature of unaffiliated members might never be able to agree on a single best policy choice without some institution constraining their options.<ref>{{cite journal | last = McKelvey | first = Richard D. | title = Intransitivities in multidimensional voting bodies | journal = Journal of Economic Theory | volume = 12 | pages = 472–482 | year = 1976| doi = 10.1016/0022-0531(76)90040-5 }}</ref><ref>{{cite journal | last1 = Schofield | first1 = Norman | title = Generic instability of majority rule | journal = Review of Economic Studies | volume = 50 | issue = 4 | pages = 695–705 | year = 1983| doi = 10.2307/2297770 | jstor = 2297770 }}</ref>