The emergence of a new party of the radical left in Scotland, Rise (Respect, Independence, Socialism, Environmentalism), to be launched this weekend, has aroused much derision and allusions to Monty Python’s People's Front of Judea sketch. “How long before Rise sinks?” Ho, ho.

But it's surely a tribute to Holyrood's proportional electoral system that new political formations like this are entering the field. Unlike at Westminster, small parties have a realistic prospect of actually winning seats.

As recently as 2003, the far left Scottish Socialist Party had no fewer than six MSPs sitting in the Scottish Parliament and the Green Party had seven.

It didn't turn out too well. The SSP lost all of their seats after the party dissolved into acrimonious internal division over the libel action against the News of the World in 2006 taken by then-leader Tommy Sheridan.

Nor did the Greens manage to capitalise on their early success. They wilted to only two seats as SNP leader Alex Salmond stole their thunder by pushing renewable energy and saying no thanks to nuclear power.

But now the small parties are sensing a change in the air. The SNP are beginning finally to look a bit like a party of the establishment; well, they've been in power for more than seven years. The independence referendum created a revolution in political participation.

The Scottish Liberal Democrats are pushing up the daisies. And paradoxically, the SNP's very popularity (they may take nearly all of Labour's constituency seats next year) could leave a lot of the 56 Holyrood list seats up for grabs.

Under Holyrood's additional member system it's very hard for parties that score highly in the constituency vote to do well on the list. In fact, the Scottish Parliamentary elections are beginning look all about the list.

Labour should be first in line for “top up” list seats, which is why there’s been unprecedented jostling in the party for selection as list candidates. Polls suggest Labour should get at least 25 seats in May. But such is the turmoil in the party following the Corbyn surge that nothing is certain.

The UK Labour Party could split next month if Jeremy Corbyn becomes leader. The right of the party has been threatening a coup;Yvette Cooper warned last week of a breakaway, as with the SDP in the 1980s. Anyway you look at it, there will be blood.

This could overwhelm attempts by Labour's Scottish leader, Kezia Dugdale's, to paint a fresh radical face on Labour in this country. Most of us think Labour's share of the vote couldn't fall any further; none of us thought they would lose all but one of their Scottish MPs in May.

If nothing else, Corbynism has made people think again about what a party of the left should look like in Scotland. He has demonstrated that policies like nationalisation and wealth taxes can be popular. These votes have to go somewhere.

SNP supporters wondering what to do with their “wasted” list votes, and bored with the Greens, might well consider voting for a new left-wing nationalist party if one were available. And that is exactly the space Rise is trying to occupy because, unlike most Marxist parties of the past, it is unashamedly pro-independence.

RISE grew out of a nationalist splinter of the far left called the International Socialist Group, led by the activist Jonathon Shafi and trades union organiser Cat Boyd. This begat the Radical Independence Conference (RIC) of 2012 which brought together the post-Sheridan SSP, the Green Party and large numbers of non-aligned left supporters of independence such as Robin McAlpine of Common Weal.

RIC was the most successful venture ever seen on the far left in Scotland. In November 2014, it attracted 3,000 people to the Armadillo in Glasgow for its annual conference. That begat the Left Project and now Rise.

Now, all this may be of supreme indifference to Scottish voters, most of whom seem to be quite happy voting SNP and Labour. But we live in extraordinarily fluid times. Old party allegiances are breaking down.

A new generation of political activists has emerged among what is called the “precariat” of highly-educated, underemployed graduates lacking predictability or security. The internet has disrupted the conventional channels of communication. Radical speakers such as Cat Boyd can attract big crowds.

We know that new parties can rise from nowhere, like Syriza in Greece and Podemos in Spain, both of which are populist parties of the nationalist left.

It seems unlikely to me that Rise could pose a serious threat to Nicola Sturgeon's SNP, which has pretty much colonised social democratic and nationalist politics in Scotland. But others disagree.

Prominent writers on the independence-referendum left like Gerry Hassan say the SNP are a sham and have “done nothing to redistribute wealth in Scotland despite having been in power for nearly eight years”. Indeed, he says the Nationalists have been sneakily rewarding the middle classes through policies such as free university tuition and personal care.

This seems to me to misunderstand the nature of social democracy. Universal benefits such as free health care and free education have always been seen as essential underpinnings of the welfare state, even though they also benefit middle class people. But there's no doubt that the SNP's record fails to match its rhetoric on many social issues.

However, convincing the Scottish voters that the SNP are just New Labour in Scottish clothing is going to be a hard task. The SNP's 2015 General Election manifesto was strikingly similar to Jeremy Corbyn's left agenda: nuclear disarmament, public investment, free higher education, council housing, rejection of welfare cuts and so on.

These similarities are not accidental. The Corbynites noted the success of Ms Sturgeon's anti-austerity themes in the General Election campaign and followed her example; except, of course, that Corbyn is not a nationalist, civic or otherwise.

This is why the nationalist left in Scotland think there may be a gap in the market on the other side of the SNP. They saw the crowds that turned up to hear Mr Corbyn in Scotland recently and they want a piece of that action.

The Greens were hoping to win many of the non-SNP list votes, but they’ve suddenly realised that there’s a threat on their left from their erstwhile colleagues in RIC. This may explain why their co-convener, Patrick Harvie, made his intervention this week calling for the nationalisation of the oil industry in Scotland.

Is Ms Sturgeon worried? Not yet, though some nationalists are warning that Rise and the Greens might split the SNP vote and stop it securing another overall majority in Holyrood next May. For some, every non-SNP vote is a wasted vote.

Well, so be it. Holyrood was never designed for one-party rule. It works best with minority government, in the view of many people. There are always a few seats for newcomers to show what they can contribute.

So, welcome Rise. Politics has never been more competitive. It's a crowded and raucous marketplace of ideas as we move into a new era in which everyone is making it up as they go along.