In Ireland we like to name our coalition Governments – from 1994 to 1997, we famously had the “rainbow Government”, led by John Bruton. This week, Sinn Fein were talking about “a left coalition” comprising themselves and every other assorted left winger in Leinster House – sort of a Marxist pick-n’mix box of chocolates, where, contra Forrest Gump, you know exactly what you’re going to get.

That dream may be on the verge of being taken off the table, however, because Fianna Fáil are now mooting an entirely different kind of Government – one that could surely only be named “The Suicide Pact”.

This alternative Government would bring together Fianna Fáil, Fine Gael and – bizarrely – the Green Party. Together, the three parties would have 85 seats – a majority of 10 over all other parties, and likely enough to govern for the full five years, assuming no rows or fallings out, which is never a safe bet.

But what, exactly, do all three parties gain from it?

The most obvious thing, looking from the outside, is how utterly bereft of intellectual confidence the two larger parties are. Trying to attach the greens to their proposed Government is the giveaway on that one – neither party seems to feel as if it can deliver a popular centrist, or even right of centre, government without some kind of soft left agenda tacked on via the greens. But this isn’t a recipe for popularity – it’s a recipe for catastrophe.

The last parts of the country where FF and FG remain very popular with the electorate are also those parts of the country most hostile to the Green agenda. Cavan Monaghan, Mayo, Donegal, East Galway, north Cork, and so on are places where FF and FG performed most strongly. By contrast, Green candidates largely floundered.

A Fianna Fáil Fine Gael Government that embraces the Green agenda will be poisoned by it in the very parts of the country where it still has voters willing to back it. And what will it gain elsewhere? If those two parties have learned anything over the past decade, how can it have escaped them that pursuing a soft left or progressive agenda isn’t helping them in the big cities, where there will always be someone able to be even more progressive than they are. Fianna Fáil got 14% in Dublin in this election. Embracing the Greens is not going to suddenly make the voters of Howth think that Fianna Fáil is Ireland’s answer to Alexandra Ocasio-Cortez.

Instead, what will happen is that an FF/FG Government that goes down that road will be playing right into the hands of Sinn Fein, who are utterly shameless about pretending to care about Climate Change while opposing every unpopular Green policy. Sinn Fein TDs will make hay right across the country with petitions and marches against the FF/FG carbon tax.

And what about the Greens?

The very dynamic that hurts the two larger parties will also hurt the Greens. To get any meaningful wins at all on Climate policy, they’ll likely have to accept the economic agenda of FF and FG lock, stock, and barrel. That probably means implementing tax cuts at a time when left wing voters are expressing a huge preference for spending increases. It probably means opposing popular (but terrible) ideas on housing, like the rent freeze or the right to basically unlimited tenancy. The Greens had a good election, but most of their seats were won on the back of transfers from left wing voters, and doing well from Sinn Fein surpluses. Going into Government might increase their first preference vote if the Government does well, but it’s basically guaranteed to deprive them of the transfer-friendliness that gained them 10 extra seats at this election. Unless they’re mad, they will obviously have to be aware that this will be, for them at least, a one and done Government. And it’s a Government that is likely, at best, to implement only part of their agenda.

And then there’s Fine Gael. Having spent four years as Taoiseach, Leo Varadkar would be leading his party into “B” status. Once you accept that you’re the second party in Government, it will be very hard ever to convince the voters that you should be a leading party of Government again. The political dynamic every week will be Micheal Martin versus Mary Lou McDonald, while Varadkar has to sit there and remain quiet. The Fine Gael message will be lost.

Indeed, the party would have to figure out, while in Government, its identity. Is it the voice in Government for lower taxes and economic rigour, or is it the party for keeping Fintan O’Toole broadly onside? Trying to figure that out while simultaneously being answerable for every decision a Fianna Fáil or Green minister takes would be next to impossible.

The Greens might believe that entering such a Government is necessary, because at the end of the day, if you take them at their word, not having the Greens in Government means that we may all be dead in ten years. Political obliteration might be worth it for them. But for the two larger parties, which tend to take a longer-term view, what is there to be gained? For one of them, it means becoming the permanent third party of Irish politics. For the other, it means, most likely, one term in Government before Sinn Fein takes power anyway, and with no opportunity to address all the failings that saw it lose seats in this election, even as the main opposition.

It’s a tripartite suicide pact. If they’re that opposed to Sinn Fein, what do they have to lose from another election?