Editing Spoiler effect (section)

=== Manipulation by politicians ===
Voting systems that violate independence of irrelevant alternatives are susceptible to being manipulated by ''strategic nomination''. Such systems may produce an ''incentive to entry'', increasing a candidate's chances of winning if similar candidates join the race, or an ''incentive to exit'', reducing the candidate's chances of winning.

Some systems are particularly infamous for their ease of manipulation, such as the [[Borda count]], which exhibits a particularly severe entry incentive, letting any party "clone their way to victory" by running a large number of candidates. This famously forced de Borda to concede that "my system is meant only for honest men,"<ref name=":33">{{Cite book |last=Black |first=Duncan |url=https://books.google.com/books?id=CRdnaPy8oB4C&q=honest&pg=PA182 |title=The Theory of Committees and Elections |date=1987 |publisher=Springer Science & Business Media |isbn=9780898381894 |language=en |orig-year=1958}}</ref><ref name=":13">{{Cite book |last1=McLean |first1=Iain |url=https://books.google.com/books?id=0QPv9cg3g-sC&q=the%20voters%20found%20how%20to%20manipulate%20the%20Borda%20rule:%20not%20only%20by%20putting%20their%20most%20dangerous%20rival%20at%20the%20bottom%20of%20their%20lists,%20but%20also%20by%20truncating%20their%20lists&pg=PA40 |title=Classics of Social Choice |last2=Urken |first2=Arnold B. |last3=Hewitt |first3=Fiona |date=1995 |publisher=University of Michigan Press |isbn=978-0472104505 |language=en}}</ref> and eventually led to its abandonment by the [[French Academy of Sciences]].<ref name=":13" />

Other systems exhibit an exit incentive. The vote splitting effect in [[First-past-the-post|plurality voting]] demonstrates this method's strong exit incentive: if multiple candidates with similar views run in an election, their supporters' votes will be diluted, which may cause a unified opposition candidate to win despite having less support. This effect encourages groups of similar candidates to form an organization to make sure they don't step on each other's toes.<ref name="Armytage 2014">{{cite journal | first=James|last=Green-Armytage | title=Strategic voting and nomination | journal=Social Choice and Welfare | publisher=Springer | volume=42 | issue=1 | year=2014 | issn=0176-1714 | jstor=43663746 | pages=111–138 | doi=10.1007/s00355-013-0725-3 | s2cid=253847024 | url=http://www.jstor.org/stable/43663746 | access-date=2024-02-23 | quote=... if two or more candidates with similar views run in the same plurality election, then the voters who support those views will be divided among them, giving an advantage to other candidates with opposed views. Therefore, it is helpful for groups of fairly like-minded people to form some kind of association – that is, a political party – which fields only one candidate per election, and which provides some kind of process for deciding whom this one candidate should be – that is, a primary.}}</ref>