Editing Median voter theorem (section)

{{Short description|Theorem in political science}}{{Electoral systems sidebar|expanded=Social and collective choice}}{{Confused|median mechanism}}{{For|a discussion on applicability of the median voter theorem to different electoral systems|center squeeze}}
In [[political science]] and [[social choice theory|social choice]], the '''median voter theorem''' states that if voters and candidates are distributed along a one-dimensional [[political spectrum|spectrum]] and voters have [[single-peaked preferences]], any voting method that is [[Condorcet criterion|compatible with majority-rule]] will elect the candidate preferred by the [[median]] voter.

The theorem was first set out by [[Duncan Black]] in 1948.<ref>{{Cite journal |last=Black |first=Duncan |date=1948-02-01 |title=On the Rationale of Group Decision-making |url=https://www.journals.uchicago.edu/doi/10.1086/256633 |journal=Journal of Political Economy |language=en |volume=56 |issue=1 |pages=23–34 |doi=10.1086/256633 |issn=0022-3808 |s2cid=153953456|url-access=subscription }}</ref> He wrote that he saw a large gap in economic theory concerning how voting determines the outcome of decisions, including political decisions. Black's paper triggered research on how economics can explain voting systems.

A related but distinct argument, known as the '''Downsian model''', was developed by [[Anthony Downs]]. While often confused with the median voter theorem, the Downsian model makes a different claim: that politicians in a [[representative democracy]] will strategically move toward the median voter's position<ref name="holcombe-2006">{{cite book |last1=Holcombe |first1=Randall G. |url=https://books.google.com/books?id=aOntAAAAMAAJ |title=Public Sector Economics: The Role of Government in the American Economy |publisher=Pearson Education |year=2006 |isbn=9780131450424 |page=155}}</ref> to maximize their chances of winning elections. This happens because politicians recognize that appealing to the median voter is often the key to electoral success, based on the implications of the median voter theorem.<ref name="holcombe-2006" /><ref name="hotelling harold-1929">{{cite journal |author=Hotelling, Harold |year=1929 |title=Stability in Competition |journal=The Economic Journal |volume=39 |issue=153 |pages=41–57 |doi=10.2307/2224214 |jstor=2224214}}</ref><ref name="downs-1957">Anthony Downs, "[[An Economic Theory of Democracy]]" (1957).</ref> However, this strategic convergence only occurs in voting systems that actually satisfy the median voter property, and cannot be applied to systems like [[Instant-runoff voting|ranked choice voting]] (RCV) or [[plurality voting]] outside of limited conditions (see {{Section link|2=Hotelling–Downs model|nopage=y}}).<ref>{{Cite journal |last=McGann |first=Anthony J. |last2=Koetzle |first2=William |last3=Grofman |first3=Bernard |date=2002 |title=How an Ideologically Concentrated Minority Can Trump a Dispersed Majority: Nonmedian Voter Results for Plurality, Run-off, and Sequential Elimination Elections |url=https://www.jstor.org/stable/3088418?casa_token=0NcBsoSqKiUAAAAA:1CY5Ul4Tahqhsnupv_ZwTG3G83TDl2y7wYLsj7Lw9rkav4pTVWSodtmq7dy2jVpP8VZTd5FpUss19CupKzVvZvSU9LXP4ZlrMowV3QoFlUxr9FTRm8c&seq=3 |journal=American Journal of Political Science |volume=46 |issue=1 |pages=134–147 |doi=10.2307/3088418 |issn=0092-5853 |url-access=subscription}}</ref><ref name="myerson-1993">{{Cite journal |last1=Myerson |first1=Roger B. |last2=Weber |first2=Robert J. |date=March 1993 |title=A Theory of Voting Equilibria |url=https://www.cambridge.org/core/journals/american-political-science-review/article/abs/theory-of-voting-equilibria/64F7B2BB2FEED712B1E3A375AF86504E |journal=American Political Science Review |language=en |volume=87 |issue=1 |pages=102–114 |doi=10.2307/2938959 |issn=1537-5943 |jstor=2938959 |hdl-access=free |hdl=10419/221141}}</ref><ref>{{Cite journal |last1=Mussel |first1=Johanan D. |last2=Schlechta |first2=Henry |date=2023-07-21 |title=Australia: No party convergence where we would most expect it |url=http://journals.sagepub.com/doi/10.1177/13540688231189363 |journal=Party Politics |language=en |volume=30 |issue=6 |pages=1040–1050 |doi=10.1177/13540688231189363 |issn=1354-0688 |url-access=subscription}}</ref>