In all plurality systems Wasted votes Wasted votes are those cast for candidates or parties who did not get elected. Some number of wasted votes by this definition is practically unavoidable, but plurality systems suffer from large numbers of wasted votes. For example, in the
UK general election of 2005, 52% of votes were cast for losing candidates and 18% were excess votes, a total of 70% wasted votes. That is perhaps the most fundamental criticism of the single-member plurality system, since at least half the votes are always wasted in a district, either as being placed on un-elected candidates or being surplus to what could be needed to win. SMP is in practice similar in plurality block voting. They both operate under the "winner-takes-all" principle, which means that the party of the losing candidates in each district receive no representation, regardless of the number of votes they receive. Even the single non-transferable vote can result in very inefficient results if many candidates with small support compete or the most-popular candidates receive a large excess of votes. This is because like other plurality systems, SNTV does not transfer loser and surplus votes. Another way to count wasted votes is to see the ones that may play no part in determining the outcome. Under plurality voting for example, usually only votes for the top two candidates can be seen as really competing for the position, with only one possible to win; votes placed on other candidates are almost certain not to be used to elect anyone and therefore wasted. Sometimes not even two candidate are seen as being competitive. Due to having a history of repeatedly electing candidates of a certain party, many districts are known to have
safe seats. On such, a candidate or party has a near 100% chance that they win the seats. Supporters of others sometimes do not even bother to vote knowing of the odds that face their candidate. Alternative electoral systems, such as
proportional representation, attempt to ensure that almost all of the votes are effective in influencing the result and electing a representative, which minimizes vote wastage. Such systems decreases disproportionality in election results and are also credited for increasing voter turnout.
Tactical voting To a much greater extent than many other electoral methods, plurality electoral systems encourage
tactical voting techniques like "compromising". Voters are under pressure to vote for one of the two candidates most likely to win, even if their true preference is neither of them; because a vote for any other candidate is unlikely to lead to the preferred candidate being elected. In single-member plurality, this will instead reduce support for one of the two major candidates whom the voter might prefer to the other. Electors who prefer not to waste their vote by voting for a candidate with a very low chance of winning their constituency vote for their lesser preferred candidate who has a higher chance of winning. The minority party will then simply take votes away from one of the major parties, which could change the outcome and gain nothing for the voters. Any other party will typically need to build up its votes and credibility over a series of elections before it is seen as electable. In the
Tennessee example, if all the voters for Chattanooga and Knoxville had instead voted for Nashville, Nashville would have won (with 58% of the vote). That would have only been the third choice for those voters, but voting for their respective first choices (their own cities) actually results in their fourth choice (Memphis) being elected. The difficulty is sometimes summed up in an extreme form, as "All votes for anyone other than the second place are votes for the winner". That is because by voting for other candidates, voters have denied those votes to the second-place candidate, who could have won had they received them. It is often claimed by United States
Democrats that Democrat
Al Gore lost the
2000 Presidential Election to
Republican George W. Bush because some voters on the left voted for
Ralph Nader of the
Green Party, who, exit polls indicated, would have preferred Gore at 45% to Bush at 27%, with the rest not voting in Nader's absence. That thinking is illustrated by elections in
Puerto Rico and its three principal voter groups: the
Independentistas (pro-independence), the
Populares (pro-
commonwealth), and the
Estadistas (pro-
statehood). Historically, there has been a tendency for Independentista voters to elect Popular candidates and policies. This results in more Popular victories even though the Estadistas have the most voters on the island. It is so widely recognised that the Puerto Ricans sometimes call the Independentistas who vote for the Populares "melons" in reference to the party colours, because the fruit is green on the outside but red on the inside. Such tactical voting can cause significant perturbation to the system: • Substantial power is given to the
news media. Some voters will tend to believe the media's assertions as to who the leading contenders are likely to be in the election. Even voters who distrust the media know that other voters believe the media, and so those candidates who receive the most media attention will nonetheless be the most popular, and thus most likely to be one of the top two. • A new candidate, who is in principle supported by the majority of voters, may be considered unlikely to become one of the top two candidates, because of the lack of a track record. The candidate will thus receive fewer votes, which will then give them a reputation as a low poller in future elections, which perpetuates the problem. • The system may promote votes against than for a candidate. In the UK, entire campaigns have been organised with the aim of voting against the
Conservative Party by voting either
Labour or
Liberal Democrat. For example, in a
constituency held by the Conservatives, with the Liberal Democrats as the second-placed party and the Labour Party in third, Labour supporters might be urged to vote for the Liberal Democrat candidate, who has a smaller hurdle to overcome and more support in the constituency than their own party candidate, on the basis that Labour supporters would prefer an MP from a competing leftist or liberal party than a Conservative one. Similarly, in Labour/Liberal Democrat marginals in which the Conservatives are third, Conservative voters may be encouraged or tempted to vote Liberal Democrat to help defeat Labour. • If enough voters use this tactic, plurality voting becomes, effectively,
runoff voting, a completely different system, in which the first round is held in the court of public opinion. A good example was the
1997 Winchester by-election. Proponents of other single-winner electoral systems argue that their proposals would reduce the need for tactical voting and reduce the
spoiler effect. Other systems include the commonly used
two-round system of runoffs and
instant-runoff voting, along with less-tested and perhaps less-understood systems such as
approval voting,
score voting and
Condorcet methods.
Tactical voting is when a voter decides to vote in a way that does not represent their true preference or choice, motivated by an intent to influence election outcomes. Strategic behaviour by voters can and does influence the outcome of voting in different plurality voting systems. Strategic behaviour is when a voter casts their vote for a different party or alternative district/constituency/riding in order to induce, in their opinion, a better outcome. An example of this is when a person really likes party A but votes for party B because they do not like party C or D or because they believe that party A has little to no chance of winning. This can cause the outcome of very close votes to be swayed for the wrong reason. This might have had an impact on the
2000 United States election that was essentially decided by fewer than 600 votes, with the winner being
President Bush. When voters behave in a strategic way and expect others to do the same, they end up voting for one of the two leading candidates, making the Condorcet alternative more likely to be elected. In
gerrymandering, a party in power deliberately manipulates constituency boundaries to increase the number of seats that it wins unfairly. In brief, if a governing party G wishes to reduce the seats that will be won by opposition party O in the next election, it can create a number of constituencies in each of which O has an overwhelming majority of votes. O will win these seats, but many of its voters will waste their votes. Then, the rest of the constituencies are designed to have small majorities for G. Few G votes are wasted, and G will win many seats by small margins. As a result of the gerrymander, O's seats have cost it more votes than G's seats.
Efficiency gap: The
efficiency gap measures gerrymandering and has been scrutinized in the Supreme Court of the United States. The efficiency gap is the difference between the two parties' wasted votes, divided by the total number of votes.
In some plurality systems Fewer political parties Duverger's law is a theory that constituencies that use plurality voting will eventually become a
two-party system after enough time. The two dominating parties regularly alternate in power and easily win constituencies due to the structure of plurality voting systems. This puts smaller parties who struggle to meet the threshold of votes at a disadvantage, and inhibits growth. Studies suggest that plurality voting system fails to incentivize citizens to vote, which results in very low
voter turnouts. However, non-plurality systems such as
closed list PR may also use just as simple ballots. In cases without ballots, such as open voting by raised hands, for example, there are simpler methods that do not require checking for people who voted more than they are allowed to, for example,
approval voting.
Ease of counting With plurality voting, counting and summing up votes is generally an easy process, and this may be done on a precinct level and then summed up for a total with the same results. Some alternative methods, such as
instant-runoff-voting do not work this way and either counting has to take place centrally, or complete (non-aggregated) results from precincts need to be submitted to the central authority for results.
Arguments for single-member plurality Common arguments for specifically the single-winner variant of plurality voting are constituency representation (which all other single-winner systems provide to the same degree) and governmental stability (which is dependent on other factors as well). == Voting system attributes and comparison to non-plurality systems ==