Is it wrong to vote tactically?

Tomorrow will see the closest election in the UK for many years and there is considerable debate about whether tactical voting is acceptable (see here, here, here). This is a particularly big issue this election as the Liberal Democrats (the UK's third largest party) have had a significant rise in popularity and the vote looks to be split fairly evenly among the three parties. A three-party race causes significant problems for the 'first past the post' voting system used in the UK and the US, as it means that a party can win a seat even if 60% or 70% of the people in the seat think that it is the worst option. For example, suppose that a seat has the vote split as follows:

40% — Conservatives

38% – Liberal Democrats 

22% – Labour

The Conservatives would win this seat even if they were the third choice of all the Liberal Democrat and Labour voters. In such a case, the Labour supporters might realise that they have relatively little chance of winning and that they can avoid a worst-case scenario by voting Liberal Democrat. Voting for a party that is not your preferred party is known as tactical voting and is quite contentious.

Some people oppose tactical voting for merely tactical reasons: they think their party will do worse if people vote tactically. However, others oppose it on more philosophical grounds: they think that it is in some sense undemocratic to vote tactically, as it means that the vote tally does not directly show the support of the people. One might even suggest that the voter would be lying by casting a vote for a party that she doesn't prefer.

Whether the voter is lying or doing something undemocratic depends on the question that they are answering with their vote. If the question is 'which party is best for you?' then it would be just as illegitimate to vote based on what is best for those less fortunate for yourself, but this seems very implausible and such a case is rarely if ever made. Opponents of tactical voting might instead argue that the question is 'which party would you most prefer to be in government?' (taking into account both personal and social reasons). If this were the question, then tactical voting would in some sense be lying.

However, the electoral authorities do not typically try to specify any unique question, and still less to point out that they do not want people to vote tactically. This would be easy enough for them to write on the top of the ballot paper, but a decision is made to not do so. Instead, you are typically just asked to 'place an X next to the candidate you wish to vote for', with no description on what you must mean by voting for someone. It is thus hard to make a case that tactical voting is lying.

As to the claims that tactical voting is undemocratic, it seems clear that it is more democratic than the alternative, which is allowing a candidate to win even when the vast majority of people think they are the worst candidate.

Tactical voting would thus seem to be a valid way for people to make the best of a bad voting system, voting in whichever way it is that they think will lead to the most good. Until the UK moves to a more expressive voting system such as the Alternative Vote or Single Transferable vote systems used in Australia, it seems that tactical voting is a legitimate choice.