Tactical voting

Although it is desirable for a democratic system to encourage voters to express sincere preferences, it has been shown by the Gibbard-Satterthwaite theorem that any voting method which is completely strategy-free must be nondeterministic (that is, might not select the same outcome every time it is applied to the same set of ballots). For instance, the random ballot voting method, which randomly selects the ballot of a single voter and uses this to determine the outcome, is strategy-free, but may result in different choices being selected if applied multiple times to the same set of ballots.

However, although no practical method is strategy-free, the type of tactical voting and the extent to which it affects the timbre of the campaign and the results of the election vary dramatically from one voting system to another.

Types of tactical voting

There are different types of tactical voting:

Compromising (sometimes favorite-burying or useful vote) is a type of tactical voting in which a voter insincerely ranks an alternative higher in the hope of getting it elected. For example, in the first-past-the-post election, a voter may vote for an option they perceive as having a greater chance of winning over an option they prefer (e.g., a left-wing voter voting for a popular moderate candidate over an unpopular leftist candidate, or in order to help defeat a strong right-wing candidate.) Duverger's law suggests that, for this reason, first-past-the-post election systems will lead to two party systems in most cases.

Burying is a type of strategic voting in which a voter insincerely ranks an alternative lower in the hopes of defeating it. For example, in the Borda count or Instant-runoff voting, a voter may insincerely rank a perceived strong alternative last in order to help their preferred alternative beat it. A United States analogy would be voters of one party crossing over to vote in the other party's primary against the candidate they think might beat the candidate of their party.

Push-over or turkey-raising is a type of strategic voting in which a voter ranks a perceived weak alternative higher, but not in the hopes of getting it elected. For example, in a bloc vote where multiple votes are required, a voter may insincerely vote for a candidate they perceive as unlikely to win, in order to help their preferred candidate win.

Examples in real elections

In the 1997 UK General Election, the Democratic Left organised GROT - Get Rid Of Them - a tactical voter campaign. In 2001, the Democratic Left's successor organisation the New Politics Network organised a similar campaign tacticalvoter.net. Since then tactical voting has become a real consideration in British politics as is reflected in by-elections and by the growth in sites such as tacticalvoting.com who encourage tactical voting as a way of defusing the two party system and empowering the individual voter. In the 2005 UK General Election individuals set up tacticalvoting.net to balance the tactical voting debate.

In the Ontario general election, 1999, strategic voting was widely encouraged by opponents of the Progressive Conservative government of Mike Harris. This failed to unseat Harris, and succeeded only in suppressing the New Democratic Party vote to a historic low.

Rational voter model

Academic analysis of tactical voting is based on the rational voter model, derived from rational choice theory. In this model, voters are short-term instrumentally rational. That is, voters are only voting in order to make an impact on one election at a time (not, say, to build the political party for next election); voters have a set of sincere preferences, or utility rankings, by which to rate candidates; voters have some knowledge of each other's preferences; and voters understand how best to use tactical voting to their advantage. The extent to which this model resembles real-life elections is the subject of considerable academic debate.

Pre-election influence

Because tactical voting relies heavily on voter's perception of how other voters intend to vote, campaigns in electoral systems that promote compromise frequently focus on affecting voter's perception of campaign viability. Most campaigns craft refined media strategies to shape the way voters see their candidacy. During this phase, there can be an analogous effect where campaign donors and activists may decide whether or not to support candidates tactically with their money and labor.

In rolling elections, or runoff votes, where some voters have information about previous voters' preferences (e.g. presidential primaries in the United States, French presidential elections), candidates put disproportionate resources into competing strongly in the first few stages, because those stages affect the reaction of latter stages.

Views on tactical voting

Some people view tactical voting as providing misleading information. In this view, a ballot paper is asking the question "which of these candidates is the best?". This means that if one votes for a candidate who one does not believe is the best, then one is lying. British Labour Party politician Anne Begg considers tactical voting dangerous: [1]

"Tactical voting is fine in theory and as an intellectual discussion in the drawing room or living rooms around the country, but when you actually get to polling day and you have to vote against your principles, then it is much harder to do".

The problem is that such tactical voting would tend to overshoot and give undesired results. This greatly complicates the comparative analysis of voting systems. If tactical voting were to become significant, the perceived "advantages" of a given voting system could turn into disadvantages - and, more surprisingly, vice versa.

Tactical voting in particular systems

Steven Brams and Dudley R. Herschbach argued in a paper in Science magazine in 2000 that approval voting was the system least amenable to tactical perturbations. This may be related to the fact that approval voting does not permit preferences ('likes' or 'dislikes') to be stated at all, permitting only a statement of tolerances, that is, "which candidate could you stand to see win", as opposed to "which candidate would you like to see win".

Due to the especially deep impact of tactical voting in first past the post electoral systems, some argue that systems with three or more strong or persistent parties become in effect forms of disapproval voting, where the expression of disapproval, to keep an opponent out of office overwhelms the expression of approval, to approve a desirable candidate. Ralph Nader refers to this as the "least worst" choice, and argues that the similarity of parties and the candidates grows stronger due to the need to avoid this disapproval.

See also