In my last post I referred to the tactical situation in Oxford, and so today I propose to follow this up with the underlying theory behind why people vote as they do – as it turns out to be not so straightforward as choosing the candidate you most like the sound of!

To do so, we will be referencing a chap called Maurice Duverger, who was the first person credited with identifying a law of electoral behaviour – that in the long term, votes in a first-past-the-post system will concentrate upon the two front running candidates and decline from all others. Duverger’s law identifies a trend known as strategic desertion – whereby voters reduce their choice from the most preferred of all candidates, to the most preferred of the options that stand a chance of winning.

To demonstrate this, let me bring in a scenario my wife may face as a teacher. Her class of 20 students are offered 20 minutes ‘Golden Time’ each fortnight as a reward for their hard work, and so she allows them to decide between three options – reading; playing Pictionary; or watching The Great British Bake Off. Using first-past-the-post, as we do for General Elections, the results are:

Pictionary        8
Bake Off          7
Reading           5

Clearly, there are two front-runners, and so next time around two of the readers (who decided they hate Pictionary) change their minds and vote for the Bake Off instead. The time after that another two readers vote for Pictionary, deciding that Bake Off reminds them too much of Home Economics, leaving one poor reader stubbornly hoping someone might change their mind. In the long term therefore, you have two blocks of votes, and the contest is between those wavering voters (most probably but not exclusively the former readers) who may be persuaded to change their vote compared to last time.

So when I refer to the ‘tactical situation’ it principally acknowledges that in certain seats the party or candidate you most like the sound of might not have the chance to win – first-past-the-post encourages voters to choose an option that may not have been their first preference, thus favouring the two leading candidates in a contest. Most people vote because they desire to impact the final outcome, and hence they aim to support a candidate with a good chance of winning – although as I have just commented, in Oxford it is not necessarily evident which candidate is most likely to challenge the incumbent!

There is more that I can say on this topic – we are only touching on themes such as tactical rather than expressive voting, or why a party can be strong in one area but stand no chance elsewhere. I’ll instead summarise the take home point – when you cast your ballot next May, unless your most preferred candidate is obviously in the running you may have to choose between voting for the party you most prefer, thereby setting a marker for future elections, or instead determining which of the candidates most likely to win you most want to see win. With the new Parliament set to be very very tight in terms of whether one party will win an overall majority, your local MP is likely to matter more than ever – so I would counsel making your vote count!