A guide to the pros and cons of AV

(ALAMY)

For AV...

The first-past-the-post system is unfair

This seems incontestable. Under FPTP MPs can get elected with tiny amounts of public support. In 2005 George Galloway polled the votes of only 18.4 per cent of his constituents yet got to the Commons. It distorts the national picture as well. In 1974 the Conservatives won most votes in the February general election but Labour won most seats. In 2005 Labour won 55.2 per cent of seats with 35.2 per cent of the votes (and the support of just 21.6 per cent of the electorate). Even the 2010 election which brought in the Coalition was unfair: it took 119,780 votes to elect a Liberal Democrat MP but only 33,470 to elect a Labour one.

This is a "once in a generation" chance for change

This too seems incontestable. If there is a No vote tomorrow, and especially if it is a convincing vote, it is very unlikely that the alternative vote (AV) or any proper proportional system of voting will be introduced in British parliamentary elections for many years. If, however, there is a Yes vote it will encourage those who believe in getting full PR to redouble their efforts. A Yes vote will stop critics from claiming that the British people have voted on electoral reform already and voted No.

AV is fairer than first past the post

This is not quite so clear-cut. The AV system is a different system and, The Independent believes, a better one. But it might not invariably be fairer.

Under FPTP the person with the most votes wins. Under AV voters can nominate 2nd, 3rd and 4th preferences so that if their favoured candidate is eliminated they can still have "a say" until one candidate gets more than 50 per cent of the support.

As a study by the Political Studies Association points out, under FPTP how well a candidate does depends partly on how popular he or she is and partly on how many other similar candidates are running in the constituency. In a constituency with one left-wing candidate and three right-wing candidates, the left-wing candidate could win even if right-wing voters are in the majority because the right-wing vote splits.

AV is designed to prevent such outcomes. It allows the right-wing voters to coalesce around the most popular right-wing candidate and secure the seat. Thus, in such scenarios AV is more likely than FPTP to elect the candidate with broadest support.

But it would also disadvantage the candidate with the most individual support (first preference votes) who loses out in subsequent rounds to a candidate who is possibly less polarising. Thus the No campaign is right to say that AV could lead to the election of the "least unpopular" candidate.

AV is a more proportional system than FPTP

AV is not a proportional system like the single transferable vote system with which it is confused and does not generally help small parties win seats. In fact it can exaggerate the over-representation of the largest party and would have given Labour an even bigger landslide in 1997. Like FPTP, AV can produce biased election results where two parties with the same vote shares secure very different numbers of seats. It is thus possible, under AV as under FPTP, for one party to win most votes while another wins most seats.

AV would end safe seats for life

AV might reduce the number of safe seats – but it would not eliminate them. Seats where one party regularly scores more than 50 per cent of the vote (210 seats at the last election) would remain safe.

AV could make a difference in some seats that are fairly safe by making them less safe. In recent elections this would have been most likely in Conservative-held seats where Labour and the Liberal Democrats both won substantial votes. Conversely though, AV would make some seats safer. This is clearest in many Liberal Democrat seats where the party would be strengthened by lower preference votes. In recent elections it would also have applied to some Labour-held seats where the Conservatives came second and the Liberal Democrats were a strong third. However given the nature of the Coalition Government the effect could be very different in 2015.

AV would reduce the likelihood of another expenses scandal

The idea here is that laxity over expenses was a result of safe seats occurring under the FPTP system. But the Political Studies Association found very little evidence for that.

AV is a step in the right direction

This is the Yes argument in a nutshell. AV is far from perfect but it is fairer than FPTP, and it would leave open the prospect of further reform.

Against AV...

If it ain't broke, don't fix it

Arguably the most persuasive argument for voting No. First past the post has served us well for generations. Why risk tampering with the system? The counter-argument (see above) is that the current system hasn't really served us particularly well.

First past the post produces strong governments. AV would produce endless coalitions

The current Coalition Government, produced by FPTP, demonstrates the flaw in this argument. It is also far from clear that strong government is desirable, if it is unrepresentative.

First past the post is simpler than AV

This much is true. With FPTP, you put one "X" in one box and your vote is counted. But that doesn't necessarily lead on to the next argument...

AV is too complicated for most voters to understand

The No campaign suggests that even if voters cast a valid ballot, they might fail to express themselves effectively because they do not understand how AV works.

In Australia, which uses AV, many voters do not work out their own preference distribution and follow a "how-to-vote card" issued by their favoured party. In recent elections, slightly more than half of voters have reported using such cards. On the other hand, almost half of all voters said they thought through their own preference ordering.

But research also suggests that, even after decades, many voters do not understand FPTP. Focus-group research in 1998 found that many participants could not explain how FPTP worked. For example, "many seemed unaware that MPs could be elected with only a minority of the vote".

AV will cost us £250m

The No campaign is right to say that the AV referendum will cost about £90m to carry out (and that's been spent anyway) – but its claim that an extra £156m will be incurred because of the need to bring in new electronic voting machines is disputed by the Yes campaign. The Government has no plans to bring in electronic voting machines if AV is adopted, and they are not used in Australia – which also has AV – so it's hard to see how that claim is justified.

AV would give BNP supporters more power at the ballot box

In reality it is unlikely the electoral chances of the BNP would be vastly different under either system. Researchers at the IPPR think-tank have run numerous simulations to test the claim and have reported that the votes of BNP voters would rarely prove "decisive" in an election.

AV gives some people more votes than others

This is wrong. Under AV, each voter's vote has exactly the same value.

In the first round of counting, everyone's first preference is counted as one vote. In the second round, if your favourite candidate is still in the race, your first preference still counts for one vote. If your favourite candidate was eliminated, your first preference now counts for zero but your second preference counts as one. From each ballot paper, only one vote is being counted.

A second argument (often confused with the first) is that AV gives higher and lower preferences equal weight: it treats a sixth preference as one vote just as it does a first preference.

This is true: when a sixth preference is counted, it is given the same weight as a first preference. In another sense, however, it is not true: AV gives extra weight to higher preferences by counting them first. A candidate may be the second choice of most voters, but if he does not capture a decent share of first preferences, he will be eliminated from the race before this broad support can be tapped.

AV means more hung parliaments

In modelling of the past seven elections, only the most recent election would definitely have delivered a hung parliament – just as under FPTP. However, AV would have slightly increased support for the Liberal Democrats – thus increasing the likelihood of hung parliaments a little. Some simulations suggest a hung parliament in the close election of 1992.

Only Australia, Fiji and Papua New Guinea use AV

Sort of true: Fiji is in fact ruled by a military dictatorship and is not holding elections at the moment at all. However, the broader point is that if AV is so good, why is it not used by more countries? Systems that are more proportional than FPTP are used throughout Europe and it was Tory opposition to full PR that stopped Britain having a referendum on a truly proportional system.

A study by the academics David Farrell and Ian McAllister found that voters are more satisfied with democracy in countries where the electoral system allows them to express more choice among candidates (such as AV) rather than less (such as FPTP). The effect was, however, small.