Tactical voting in our democracy

Leaders like Mayawati and Navjot Singh Sidhu were barred from campaigning for two-three days by the Election Commission (EC) in this Lok Sabha elections for mixing religion with political discourse while electioneering. Supposedly they crossed the lakshmanrekha while engineering "tactical voting" to get votes from minority communities. There were several accusations of "vote transfer" too in this election. In fact, "tactical voting" is very common in a multi-party democracy like India. There is data evidence that a significant section of voters do vote differently in Lok Sabha and state Assembly elections. Isn’t that also tactical voting?

In his seminal book An Economic Theory of Democracy (1957, p. 48), Anthony Downs concluded that rational voters do not vote for their most preferred candidate when they think that candidate is not likely to win —rather a voter “decides what party he believes will benefit him most; then he tries to estimate whether this party has any chance of winning”, of course by necessarily predicting “how other citizens will vote by estimating their preferences”. Thus, voting for a less preferred but more generally popular candidate is very common in a simple plurality election where the third-party supporters usually vote for one of the major parties. In the popular Gibbard-Satterthwaite theorem in social choice theory dealing with deterministic ordinal electoral systems with a single winner, every voting rule is susceptible to tactical voting — in certain conditions some voter’s sincere ballot may not defend their opinion best. It is known as “tactical voting” in the UK, and “strategic voting” in the US elections. Conventional wisdom suggests that “tactical voting” should be highest in seats that are closely contested.

It is never easy to measure the quantum of tactical votes as it requires knowledge of both individuals’ voting choices as well as their unobserved preferences. I didn’t see any serious attempt from the social scientists or pollsters to estimate the percentages of tactical votes favouring or opposing any party in important elections. But there are a few estimates in other countries.

Just prior to the 2005 general election in the UK, BBC noted that “there is a strong interest among British voters in tactical voting”. In the UK, tactical voting played a significant role in the 2010 election also, mainly for Liberal-Democratic voters supporting Labour. Left-leaning newspapers like the Daily Mirror, The Guardian, The Independent and New Statesman advised voters to vote tactically and many proposed voting guides such as identifying constituencies in which voters should consider voting tactically like “Lib Dems Vote Labour Here” and “Labour Vote Lib Dem Here”. Two days before the election, Labour leader Ed Balls said that Labour supporters in Conservative-Liberal Democrat marginal seats should strongly consider voting tactically for Liberal Democrat candidates. 

Then the UK’s 2017 general elections was a “hold your nose” vote; an Electoral Reform Society report claims that 6.5 million people (more than 20 per cent of voters) said they planned to choose a candidate most likely to beat the one they disliked. They voted tactically to prevent a “hard Brexit” or another Conservative government.

Thirty per cent of Canadian voters (over 5 million) are non-partisan, and they consider a host of issues including party platforms, leaders, and electability to vote. Justin Trudeau won in Canada’s 2015 election, when in a span of three weeks, 1.4 million voters changed their mind from New Democratic Party to Liberal. In Slovenia, 30 per cent voters voted tactically in their parliamentary election in 2011. During the 2018 parliamentary election in Hungary, several websites such as taktikaiszavazas.hu (meaning “tactical voting”) promoted the idea to vote for opposition candidates with the highest probability of winning a given seat, which was adopted by about one-fourth opposition voters.

There is a widespread belief that single transferable vote resists tactical voting. Reducing incentives to tactical voting was the primary argument behind the unsuccessful United Kingdom Alternative Vote referendum in 2011 to change the voting system in the UK from First-Past-The-Post to alternative voting.

What’s the approximate percentage of "tactical voting" in India? Nobody knows. However, although it should vary from one part of the country to another, given the complex multi-party system of the country, can it be less than the corresponding estimates obtained from the UK or Slovenia? If not, then it’s more than the percentages of vote shares of many major (or every?) political parties in India. And what about a "tactical map" of the country by plotting the estimated tactical vote shares in different constituencies using different colours on a map of India? Psephologists and social scientists might have lot more attention to pay to "tactical voting" statistics for a better understanding of the democracy.

The author is professor of Statistics at the Indian Statistical Institute, Kolkata