An electoral system where voters can rank one, some, or all candidates in order of preference is called optional preferential voting (OPV). In Australia, this system is used to elect the lower house in NSW state elections and for QLD state and local government elections. QLD and NSW call the system optional preferential voting, even though it is still compulsory to turn up and vote. OPV is a way to get rid of compulsory voting by stealth, without actually saving people the trouble of voting. Most people who promote it have a fundamental misunderstanding of how preferential voting works. They tend to think that being forced to rank the two major parties somehow works in the favour of those two parties. In fact, the opposite is true. Optional preferential voting is a dream come true for the major parties and will help them hold on to power, regardless of their performance.
Optional preferential voting misleads most voters and is often promoted on fundamentally undemocratic principles. It is based on misidentifying the source of the two party duopoly, which is single member electorates rather than compulsory voting or preferential voting. Finally, optional preferential voting is likely to benefit the coalition above the Labor party in the short term, by fragmenting left wing voters under a 'divide and conquer' strategy.
Optional preferential voting creates a 'perverse disincentive' for minor parties to run, because their presence on the ballot paper could contribute to the victory of their least favoured major party. In fact, optional preferential voting is probably the main reason for the formal merging of the Liberal and National parties in Queensland. Thus, the system has already contributed to a reduction in voter choice. This may be considered as a 'coup' for Labor, as it has prevented the coalition from competing under two different brands. However, it is a pyrrhic victory and the voting public (and democracy) are the losers. Labor is now finding itself facing the same dilemma with the Greens, only for them, merging is not an option.
So where does this perverse disincentive come from? Ultimately, it comes from the mixture of compulsory and optional votes in the runoff elections. OPV reintroduces the spoiler effect, which is the main reason for using preferential voting instead of first past the post. The difference is that there is no incentive on the part of the voter to vote insincerely. There is only an incentive on the part of candidates to withdraw 'insincerely'. That is, not out of self interest or for the community as a whole, but to overcome a flaw in the system that could cause their candidacy to create an outcome they do not want to see. This is explained further below.
Optional preferential voting combined with compulsory voting is irrational, because it forces people to turn up and participate in the first election, but allows them to not participate in the more important final rounds of elections where the leader is actually chosen. However, this distinction depends on their political views. Some members of the public are compelled to vote in every round of elections, while others are only compelled to vote in the first, least important round. It is the supporters of the major parties that find themselves compelled to participate in every round. Obviously, this benefits the major parties.
As soon as preferences are distributed, a situation arises where there is a mixture of compulsory (first preference) votes and optional (later preference) votes competing against each other. Thus the system favours some parties over others, because some parties will go into the final round relying more heavily on compulsory first preferences, while others will rely more heavily on 2nd and 3rd preferences. The parties that have more first preferences votes have more compulsory votes and benefit more from the compulsion to turn up to the ballot box than parties that rely more on later preferences. Whatever argument is used to promote placing more value on the first preference gets reversed when that first preference vote is not provided voluntarily.
Which specific party obtains the most short term benefit from this system will vary over time, as it depends on how successful competing minor parties are and which major parties those minor parties are competing against. Over the long term, the net result will be to artificially reinforce the two major parties and make it harder for minor parties to compete (and possibly replace them). It creates a non-level playing field, because the major parties tend to benefit more from the votes that are compulsory. The party that benefits most will be the party with the least competition from within its side of the left/right divide. This explains why the concept was pushed by the Labor party after the demise of the Democrats, but before the Greens gained significant votes in the lower house. Now that the Greens take a significant number of first preference votes from Labor they are unlikely to pursue the change in other states, but we are likely to be stuck with OPV in QLD and NSW.
Compulsory voting is not about making people get out of bed on a Saturday, it is about fulfilling a civic duty to participate in democracy. Forcing people to participate in the least important rounds of the election but not the most important rounds does not make sense.
For this reason, optional preferential voting should only be implemented where voting is entirely optional. More importantly, the public debate should focus on whether voting should be compulsory or optional. It has nothing to do with how preferential voting works, yet the promoters of optional preferential voting claim that it does.
Optional preferential voting is very likely to be confused with above the line voting in the Senate and thus is likely to cause people to vote in a way they did not intend. They are likely to assume (as the author once did) that if you rank one candidate (as encouraged by most parties) then your preferences will be directed according to a list submitted by the party prior to the election. People who rank one candidate are likely to have their vote removed from the election against their wishes. It is misleading to have two separate voting systems in Australia that allow people to vote this way, but treat the votes in completely different ways. This difference is not highlighted on either ballot paper.
Optional preferential voting could make sense if voting was entirely optional. If it is compulsory to turn up and vote, then optional preferential voting is irrational. To understand this, it is important to realise that in preferential voting systems, there is not one election, but a series of elections. Multiple elections are held to eliminate the spoiler effect, which greatly assists the two major parties at the expense of the minor parties. Rather than simply electing the candidate with the most votes, the candidate with the least votes is eliminated from the race and another election is held with a smaller pool of candidates. This process is continued, if necessary, until there are only two remaining candidates. In some countries (e.g. France) there are actually multiple polling days. However, preferential voting allows people to vote once and participate in every election. In each election, your vote goes to the remaining candidate who is highest on your list of preferences. In this way, preferential voting can never work against your intentions. Your vote always goes to whichever remaining candidate you would most prefer.
Those who promote optional preferential voting without the removal of compulsory voting at the same time do so by misrepresenting the nature of preferential voting as being antidemocratic. They insist that ranking the two major parties somehow helps them maintain the two party stronghold on power and that it somehow penalises the minor party they vote for. Nothing could be further from the truth. The minor parties are eliminated during the earlier rounds of elections because few people vote for them. This is the essence of democracy. Most elections come down to a race between the two major parties because the vast majority of people vote for those two major parties. It is not until the minor parties are eliminated that the votes get passed on to the major parties. This is a blessing as it allows people to vote for minor parties while still getting a say in the final round of elections. In countries such as the US where voters are not allowed to rank all the candidates, most minor party supporters end up voting for a major party so as not to waste their vote.
Remember that the two major parties are the two major parties because the majority of people rank them first. Promoters of optional preferential voting often insist that ranking a party anywhere but last is a vote 'for' that party, with the implication being that it can work against the minor parties you rank higher. This is not true, as your vote only goes to your second last preference after your third last, and all higher preferences, have already been eliminated from the race via a democratic process. You do not vote 'for' or against candidates, you rank them in order of preference, giving you the maximum possible say in the outcome of the election.
The question of whether to make voting compulsory or optional is entirely separable from the workings of preferential voting. By focusing on the ranking of the two major parties, the proponents of optional preferential voting (under a compulsory system) are misleading people about how preferential voting works, then trying to link the non-existent problems with the fact that ranking all candidates is compulsory.
In fact, the proponents of optional preferential voting, whether it be under a compulsory or optional voting scenario, are actually helping the major parties, even though they claim the opposite. Most parties in QLD and NSW encourage people to "vote 1", for only one candidate. By not encouraging people to pass their votes on to the other minor parties and eventually the major parties, they assist the major parties in holding on to power. They prevent the minor party voters from pooling their vote, encouraging the minor party votes to be fragmented and never pose a threat to the major parties. The Greens for example are only a minor party compared to Labor and Liberal. Compared to most Australian political parties they are a very large party and gain a lot of ground by being ranked second, third etc above Labor and Liberal. The Greens and Family First benefit far more from Australia's traditional (compulsory) version of preferential voting than the two major parties (and deservedly so).
Another argument often put forward by promoters of optional preferential voting is that the two major parties are indistinguishable. This is nothing more than a lame copout. While the two major parties have similar policies, the difference between them gets more air time in the media than all of the minor parties combined. It gets more air time because it is the most important decision to make on polling day.
Optional preferential voting is often promoted out of a person's frustration at not getting their way, because the two major parties always get into power. Not only is this an anti-democratic sentiment, given that the major parties are the major parties because people vote for them, it is counterproductive as optional preferential voting helps the two major parties maintain a stranglehold on power.
So why do the two major parties hold almost 100% of lower house seats between them, even though they only represent about 80% of the people? The reason is not preferential voting. Rather, it is caused by single member electorates. Each electorate only elects a single representative, so it will almost always be a major party candidate. Optional preferential voting will not fix this, just make it worse. Note that there are major reforms that could fix this problem; it's just that the decision is not based on a single problem but a fundamental trade-off between multiple issues.
Finally, optional preferential voting is likely to benefit the coalition above the Labor party, at least in the short term, by fragmenting left wing voters under a 'divide and conquer' strategy. The reason for this is that the Liberal and National parties tend to be separated geographically, which reduces competition between them in single member electorates. Under the merged LNP in QLD, the competition has been avoided completely. Therefore their vote will not be split if people only vote for one candidate. The next biggest conservative party is either One Nation or Family First, however both of these receive far fewer votes than the main left wing minor party - the Greens. By discouraging Greens supporters from ranking other candidates, which for most of them involves putting Labor above Liberal, the promoters of optional preferential voting are assisting the coalition to gain power.
However, this is unlikely to remain the case forever as the landscape of Australian politics is continually changing. It is just as likely to assist Labor to get into power at some time in the future. The only thing that is certain is that optional preferential voting will make it easier for the two major parties to hold onto power between them and keep the minor parties out of the race.