Joseph Stalin allegedly said "those who cast the votes decide nothing, those who count the votes decide everything". As the Western Australian Senate election debacle showed, counting votes is definitely a serious business. But what is even more serious is the task of deciding which voting system should be used to elect candidates.

Perhaps surprisingly, it's the current parliamentarians that get to decide the rules that govern subsequent elections. Even more intriguingly the Abbott government and Greens Senator Lee Rhiannon are reportedly discussing a deal to make fundamental changes to the way senators are elected. But despite the significance of the issue, the media and political attention is focused elsewhere.

Australia's preferential voting system is as much maligned as it is misunderstood, so before explaining the changes that the Liberals and parts of the Greens are inching towards, and the other options on the table, it's important to explain a few key concepts.

Imagine you wanted your flatmate to buy you some takeaway dinner on their way home from work. You could ask them to get you a hamburger if they could find one, or a kebab if there were no burgers, or some Thai food if there was none of either. You might not realise it, but if you structured your request in that way, then you have effectively voted preferentially. That is you made it clear what you wanted to happen if your first or second preference wasn't available. The Australian voting system allows you to do the same when it comes to candidates. You put a 1 next to the candidate you like the best and, if few others share your support and that candidate loses, your vote helps elect the candidate you liked second best, or third best.

The US is different. In the 2000 presidential election, George W. Bush and his "hanging chads" defeated Al Gore in the crucial race in Florida. While the dodgy, and privately owned, voting machine played a role, so too did the first-past-the-post system. While Bush only beat Gore by 537 votes, the majority of the 97,421 people who voted for Ralph Nader (the Green Party's presidential candidate) almost certainly preferred Gore to Bush. In Australia their second preferences would have almost certainty elected Gore. In the US it doesn't. Rules count.

To be clear, Liberal discussions with Lee Rhiannon will not be around dumping our electoral system and replacing it with the US model, but there are changes on the table that would move us closer in that direction. The Greens have already released research showing that they think their preferred changes would help them win more seats, and while the Liberals haven't been so crass, presumably they too believe the changes they are proposing will improve rather than impede their electoral prospects.

The apparent impetus for this most unlikely of political allegiances is the result of the 2013 Senate election. In the first attempt to run the WA senate election, the little known Wayne Dropulich nearly won a Senate seat on a primary vote of only 0.23 per cent. In Victoria the Motorist's party's Ricky Muir succeeded in winning a Senate seat with a vote of just 0.51 per cent of the primary vote. Such results have led to widely held view that there is 'something wrong' with our voting system and that we "need to do something". But those who want change should be careful of what they wish for. Rules matter.

There is no perfect way to elect representatives in a democracy. Leaving aside the diverse approaches used in democracies around the world, Kenneth Arrow won the Noble Prize in economics for his impossibility theorem which shows that when there are three or more candidates in an election it is impossible to design a ballot which ensures that the outcome will perfectly reflect the community preferences.

As the number of Senate candidates in Australian elections has risen, so too has the difficulty of allocating preferences increased. It's fair to say that most voters do not really have strong preferences about the hundreds of candidates that can populate a Senate ballot paper. The current Senate voting system gives voters a choice in how to respond to this reality. They can either vote "above the line" for a single party, and let the party of their choice allocate their preferences for them; or they can vote 'below the line' and take complete control of the flow of their vote from their most preferred candidate to their least.

Given that the whole point of an election is to trust a party to make important decisions on our behalf, it's not surprising that the vast majority of Australian voters trust parties to allocate preferences and opt to vote above the line.

The "problem" that the Liberals and Rhiannon seem determined to solve is that of senators with very low primary votes being elected on the basis of preference flows from other parties. While we should always be open to improving our democracy, it is worth highlighting that there has been little concern about the very small number of votes required to elect major party senators. A whole 749 people in all of NSW put a [1] next to the Coalition's John Williams. Despite coming in 20th in primary votes, he took one of the six seats on offer.

The model being discussed by the Liberals and Greens would change the Senate voting rules to create an "optional preferential" system for above the line voting. While this will potentially increase the number of people who can bypass the preference deals done by parties, it will also significantly increase the likelihood that some blocks of votes will be 'split' in the way that Nader voters harmed the chances of Al Gore. The consequences of changing the rules could be as dramatic as they are unpredictable.

There are other options. David Leyonhjelm has supported a call by the respected psephologist, Malcolm Mackerras for optional preferential voting for those voting below the line. Rather than express a preference for up to a hundred candidates this model would allow you to simply preference your favourite dozen candidates and leave the other boxes blank.

And both yours truly, and Professor George Williams have separately argued for a simple threshold test to be added to the current system in which the existing above and below the line system is maintained but only a candidate who receives more than 2 or 4 per cent of the vote can ever be elected.

There is a big difference between agreeing that the current system can be improved and accepting that any proposed change is an improvement. If we are to do something as significant as change the way our Senators are elected, it seems obvious that a Senate inquiry in which all of the current Senators, and the public at large, can have their say.

If we need Ray Martin to look into the way we choose talk-show guests, surely we need to take an even closer look at the way that our senators are selected. To those who simply want change, be careful what you wish for.

Richard Denniss is chief economist at The Australia Institute.

Twitter @RDNS_TAI