“You’ve been told Labor can’t win — but they can. The evidence was there all along.” Thus did Mark Kenny, in Fairfax earlier this week, make his “brag hedge” bet. The “brag hedge” is when you back the five longest-odds horses in every race at the meeting. One of them is bound to come in. When they do, you produce the ticket and say “got it!”. The dozens of others stay in your pocket. You have lost hundreds overall, but to your friends, you are a savant.

Yep, Labor might win this on a 4.4% swing, and with no net loss of the ultra-marginals that the Libs could take in a reverse swing. The polls could be wrong, the anger with the Coalition could be out there, and Medicare could be the issue that swings it again. On the other hand, this could be a Miliband Down Under result, with nationwide polls showing a simplistic and inaccurate result, and causing people to ignore a gut feeling — that Bill Shorten, to many, simply does not look like prime ministerial material.

But if the polls are accurate the “third result” hoves into view — a majority Labor raw vote, with a minority of the lower house seats, and a Senate with a crossbench that is willing to do any and all horse-trading. That’s the result people should be focusing on, because it will be a moment when actually existing democracy in Australia can be reformed — or will corrode further.

[Poll Bludger: Nick Xenophon, kingmaker]

There’s no point considering the reverse result — a Liberal vote majority, with a minority of the seats. The odds are small. For Labor, however, the question is crucial. Should they be cheated out of government a second time in 20 years, what will their response be? This election hasn’t been about ideas, but it is about major differences of policy. The legitimacy of the result is particularly important, because it is clear that the Coalition would like to dismantle and privatise parts of Medicare, and other parts of what remains of the Australian social democratic state. That direction of travel would be difficult to reverse in a society with a low tolerance for tax rises, buy-backs and contract cancellations. So in terms of the particular composition of the state, and its role in fairness and universal provision.

So Labor, and those pundits who identify with Labor, need to be posing this very basic question: what will they advocate and do, if such a result comes about? Should the Coalition win on a minority, and stuff the next budget full of measures that make major structural changes to the Australian state, will they have the courage to declare that the government has no mandate to implement such changes — and throw away the budget-and-supply conventions? Would the Greens join them in this? Would NXT and other small groupings and independents?

Morally speaking, the issue’s a no-brainer; they should, absolutely. Keeping Medicare public is like keeping a winter coat in service; once the first thread is pulled, it’s on the way to being gone. Last time, the co-pay was headed off only by the relentless guerrilla campaign of Clive Palmer, inconvenient as that is for everyone to admit. This time, Labor may have to make the major stand itself. That’s scary for them. Politically, they need to show that they will actually stand up for that other principles, if there has been a decent swing back to them. But they’re members of the political caste, as well, willing to engage in the turn-taking that Australian politics demands.

[Rundle: even Pauline Hanson might be good for the Senate]

This possibility is part of the paradox of single-member exhaustive preferential systems. In every seat, they will always deliver a 50%-plus-one minimum vote for the successful candidate. But summed together, they can then produce a paradoxical minority vote victory. Since the whole point of the exhaustive preferential system is to avoid minority-vote governments, how can there be any doubt that such a government lacks legitimacy? Only by endorsing the liberal idea — that 150 people of conscience, elected to seats, come to Canberra with no prior loyalties, and choose a leader to present to the governor-general — which was a fiction from the start. The parties predate the system adopted in 1901.

The other paradoxical consequence of such a result would be to increase the legitimacy of a hung Senate as an autonomous chamber, rather than one of review. With a majority vote/seat government, there is some pressure on a Senate crossbench to give consideration to the idea that the public voted up a mandate (by however slim a majority, a ridiculous system in itself), which should be honoured in the red benches.

With a split vote/seat result, there is no such principle at play. The people have given the Senate no guide to action, in their split vote. The crossbenchers can claim a legitimacy in pursuing their party’s aims absolutely — since they were elected in a system that more accurately reflects such wishes. With Senate horse-trading thus licensed as democracy’s true expression, the Senate becomes the de facto seat of government.

Yes, I have banged on about this once or twice before. I will continue to do so. The more that independent and small-party candidates become viable in the lower house, the more likely it is that an exhaustive preferential system will deliver close results lacking legitimacy. The system was designed for an era of class politics, in which three monolithic parties contended (Labor, the non-Labor urban party of varying names, and the Country Party. The right got it as a trade-off with Labor, who wanted compulsory voting). Society is now fragmented into a set of sub-classes, constituted in a different manner. The system is no longer fit for purpose.

The long-term question is what we’ll do about it. The short-term question is what Labor will do if an anomalous result is thrown up this time: act as the political representation of its people, and the progressive spirit, or meekly fold under as creatures of the system, an agent of its dominance over the public, rather than a representation of them. Meanwhile, come Saturday week, whatever will have happened, I will have had that. That’s my brag hedge, or fiercely independent political commentary, as it’s otherwise known.