Look at those Greens, trying to stack the deck to ensure they cling to power, eh? Except that argument makes little sense and stops us having a proper squiz at how we should run the country

Politics is an odd kind of game that sometimes requires a ruthless self-interest and at others altruistic self-sacrifice. It's a patchwork of ideals and deals, virtue and vice, gamble and calculation.

It can sometimes be hard to figure out which is which when it comes to the MMP electing threshold, which currently requires a party to win a seat or five percent of the party vote to gain entry to parliament. 

The Green Party has decided to make the case for a four percent threshold, down from the current five percent. They want the change before the 2020 election.

A-ha, cry the critics. A craven ploy by the "endangered" Greens to cling to power, given the party seems to be stuck between four and seven percent in the Ardern-era. Why risk falling off the bottom rung? Better to connive to stay alive. Those sneaky Greens.

It's a knee-jerk response with little to recommend it. The Greens have always backed a lower threshold, even when the polls had them in double digits. And it's arguable that a lower threshold could lower their vote. If centre-left voters are happy with Labour and Ardern, they could feel more comfortable backing the dominant and more centrist party in the knowledge the Greens can stay in power with fewer votes.

Equally, it could open the door to parties that may chip into the Green's support – TOP and Sustainable New Zealand. If, say, TOP start showing up at three percent in the polls, some voters toying with the Greens could start shopping with Geoff Simmons and co. Four percent presents the Greens with some risk.

Party positions have always been curious when it comes to the threshold. In 2012 when the Electoral Commission recommended a drop to four percent, National stalled on it, when they could have benefited from opening the door to the Conservative Party. As it turned out, their bet paid off and they held onto power even though Colin Craig's lot took 3.97 percent. At the same time Labour backed four percent, even when it could have cost them.

New Zealand First has always supported the five percent threshold, even when they were tossed out of parliament for falling below it (and losing Tauranga). That could be a risky position to take again this term, given New Zealand First is stuck in a sub-five percent rut this year.  But you can equally argue that the five percent threshold helps fend off contenders to Winston Peters' monarch-maker title, because no other party can get a toe-hold or has a leader with the political antennae and talent of Peters.

The oft-wise Danyl McLauchlan has made the case that Peters is the very reason to keep it high. To stop rewarding his cynical brand of politics. But keeping or changing the law because of a single person or example is a poor way to decide your democratic path.

Like the cheap shots I'm seeing on social media, that falls into the trap of turning this into a personality debate, when it needs to stay bedded in principle.

You'll get good people and bad people in parliament, regardless of the threshold. It's hard to resist the conclusion that a lower threshold will let in more fringe views. It will make room for people willing to play the system and voters' baser instincts. It's easier to twist four percent of people than it is to twist five. 

But it work both ways. A lower threshold also gives room for the dreamers who are ahead of society, pulling us towards our better selves. It allows exciting new ideas to take root. What's more, if a politician is prepared to play a big con and exploit those baser instincts, four or five percent can be irrelevant. In the US, Donald Trump won an election and has transformed his party while throwing a wrecking ball around his country's democracy. Here, Don Brash was 1.5 percent away from scaring his way into power.

The percentage point one way or another won't stop demogogues or crooks. 

The truth is there is no 'right' number. You can look at Germany with five percent and still see them struggle on for months trying to form a government or you can look at the sway tiny, racist parties are having in Israel where the threshold is a perculiar 3.25 percent. 

Yet you can also see Norway doing fine at four percent and Finland OK with no threshold at all. Five percent has hardly put our democracy in jeopardy and neither would four percent. 

Equally, I have little time for those saying we should lower it because the two major parties are so dominant now. That has changed before and will change again, regardless of the threshold. And vice versa to those saying it must stay high to keep out the nutters.

The argument in favour of lowering the threshold comes down to two main points. First, it opens the doors to new ideas. Under MMP we haven't had a single new party in parliament that didn't spring from a falling out withon one of the old parties. Hardly inspirational. At a time when so many democracies are under pressure, it could even be considered dangerous. Same-old, same-old is being heavily rejected around the world; maybe making room for some diversity and fresh thinking is not just healthy, it's vital.

Second, going by the previous election, the threshold also bans more than 130,000 voters from having the representative they selected. Bryce Edwards has pointed out that in 2008, for exmple, about 6.5 per cent had their party vote "wasted" because they voted for parties that didn't hit five percent.

As the population grows, even though the percentage of New Zealanders unheard is the same, the growing number puts more pressure on the system. Again, the threshold could act as a lid on a pot of boiling voters (if you see what I mean).

So while MMP-New Zealand style is hardly broken, let's not fall into lazy accusations of self-interest. Let's focus on what serves voters, not whose idea it was.

The Greens have done us a favour putting the state of our democracy back on the table for all of us to poke and prod at. Let's debate its current and future state of health and the principles under-pinning that, not the people daring to discuss it.