Editing Median voter theorem (section)

==Downsian model==

The '''Downsian model'''<ref>{{Cite journal |last=Berger |first=Mark M. |last2=Munger |first2=Michael C. |last3=Potthoff |first3=Richard F. |date=April 2000 |title=The Downsian Model Predicts Divergence |url=https://journals.sagepub.com/doi/10.1177/0951692800012002005 |journal=Journal of Theoretical Politics |language=en |volume=12 |issue=2 |pages=228–240 |doi=10.1177/0951692800012002005 |issn=0951-6298}}</ref><ref>{{Cite journal |last=Hansen |first=Stephen |last2=Palfrey |first2=Thomas R. |last3=Rosenthal |first3=Howard |date=1987 |title=The Downsian Model of Electoral Participation: Formal Theory and Empirical Analysis of the Constituency Size Effect |url=https://www.jstor.org/stable/30024703 |journal=Public Choice |volume=52 |issue=1 |pages=15–33 |issn=0048-5829}}</ref><ref>{{Cite journal |last=Eubank |first=William Lee |date=1986-09-01 |title=Voter rationality: A retest of the Downsian model |url=https://www.tandfonline.com/doi/abs/10.1016/0362-3319%2886%2990060-1 |journal=The Social Science Journal |volume=23 |issue=3 |pages=253–266 |doi=10.1016/0362-3319(86)90060-1 |issn=0362-3319}}</ref> (also called the '''Hotelling–Downs model''') builds on [[Harold Hotelling]]'s ''principle of minimum differentiation'', also known as [[Hotelling's law|''Hotelling's law'']]. [[Anthony Downs]] adapted Hotelling's spatial competition framework to politics in 1957, creating a model that predicts politicians will converge to the median voter's position under four conditions:

# Candidates can choose ideological positions without consequence,
# Candidates only care about winning the election (not their actual beliefs),
# All other criteria of the median voter theorem are met (i.e. voters rank candidates by ideological distance),
# The voting system satisfies the median voter criterion.

As a special case, this law applies to the situation where there are exactly two candidates in the race, if it is impossible or implausible that any more candidates will join the race, because a simple majority vote between two alternatives satisfies the [[Condorcet winner criterion|Condorcet criterion]]. 

Hotelling's original principle was first described in 1929 for business competition,<ref name="hotelling harold-1929" /> while Downs later applied this framework to electoral politics. In practice, none of these conditions hold for modern American elections, though they may have held in Hotelling's time (when nominees were often [[Dark horse|previously-unknown]] and chosen by closed [[Party caucus|party caucuses]] in ideologically diverse parties). Most importantly, politicians must win [[Partisan primary|primary elections]], which often include challengers or competitors, to be chosen as major-party nominees. As a result, politicians must compromise between appealing to the median voter in the primary and general electorates. Similar effects imply candidates do not converge to the median voter under [[Electoral system|electoral systems]] that do not satisfy the median voter theorem, including [[First-past-the-post voting|plurality voting]], [[Two-round system|plurality-with-primaries]], [[two-round system|plurality-with-runoff]], or [[instant-runoff voting|ranked-choice runoff (RCV)]].<ref name="myerson-1993" /><ref>{{Cite journal |last=Robinette |first=Robbie |date=2023-09-01 |title=Implications of strategic position choices by candidates |url=https://doi.org/10.1007/s10602-022-09378-6 |journal=Constitutional Political Economy |language=en |volume=34 |issue=3 |pages=445–457 |doi=10.1007/s10602-022-09378-6 |issn=1572-9966}}</ref>