Scott Morrison holds up a pamphlet called The Greening of Labor

It’s the election where everyone seems to want to talk about the Greens, but nobody wants to talk to the Greens. Both major parties deny any deal-making with the Greens, while each accuses its rival of this mortal sin.

Yet many people on (broadly speaking) the left of politics are obviously frustrated at this state of affairs. They see Labor and the Greens as natural allies and can’t understand why they are unable to co-operate and spend so much time fighting each other.

[Helen Razer: Why I’ll never vote for the Greens]

There’s now a book addressing that very issue: How to Vote Progressive in Australia: Labor or Green?, edited by Dennis Altman and Sean Scalmer. At its launch last night in Melbourne, two of the contributors, federal Labor MP Andrew Giles and Victorian Greens MP Ellen Sandell, tried to explain their parties’ love-hate relationship.

For some in the two parties, their differences reflect a major philosophical divergence. But neither Giles nor Sandell seemed to think anything so deep was at stake; their explanations of the failure to co-operate were much more pragmatic.

Sandell argued that Labor needed to be willing to yield some power to negotiate for progressive outcomes. Although she avowed the Greens’ aim of eventually governing in their own right, she presented them for the time being as willing, even eager, to work together with the ALP.

Giles pointed out that not all Greens were as interested in co-operation and argued that progressive results were best achieved by working within the Labor Party and by securing a majority Labor government. He cited the Andrews government in Victoria as an example of this sort of success, while Sandell argued that its more progressive policies were largely a result of electoral pressure from the Greens.

[Labouring hard on a story of Greens-Liberal conspiracies]

It seems to me that each side in this debate is in a state of denial — one about electoral reality, and one about strategic reality.

Giles, and Labor’s left in general, are in denial about the basic fact that Labor does not have anything like majority electoral support and is unlikely to ever get it. Even if it does not depend on the votes of Greens MPs, it is certainly going to depend on Greens preferences to win a majority of seats.

The model of implementing progressive policies by winning a narrow majority at an ALP conference and then governing alone on less than 40% of the primary vote (the Andrews government won with 38.1%) is a fundamentally undemocratic one, and this problem is getting worse rather than better.

Sandell and the Greens, on the other hand, are in denial about the basic strategic fact that unilaterally tying themselves to Labor does not help their bargaining position. The most eager suitor is the one that can be treated with the most disdain, because their very eagerness shows that they have nowhere else to go.

If the Greens proclaim that they will never do anything other than support Labor, then Labor has no reason to negotiate with them or address any of their concerns. Why bargain for support that you are going to get anyway?

So the short-sightedness of both parties pushes them into a zero-sum game. The Greens, having closed off the option of genuine independence, have to directly attack Labor’s seats in order to be noticed, while Labor has to demonise the very people whose support it needs in order to frighten the Liberals away from dealing with them.

What makes this all so much more destructive than it need be is our electoral system. Because parliamentary strength is based on single-member electorates, parties have to fight each other directly for territory.

It’s no coincidence that the places where Greens have formed constructive relationships with more established parties are mostly ones with proportional representation, where a party can try to maximise its vote without the same sense of fighting for the same seats.

This isn’t rocket science — New Zealand managed the change very successfully 20 years ago. There’s no reason we couldn’t do it as well.

If Labor and the Greens were serious about building a non-adversarial relationship, they would co-operate to promote electoral reform. But Labor still indulges the hope that it can govern alone from a minority base, even as it de-legitimises the voices it needs to give it power.