DURING a recent visit to Brussels, the former First Minister Alex Salmond mused about the prevailing wisdom that the “established order” was “under siege from the forces of right-wing populism”. Scotland, he argued, was an exception, for here it was “progressive pro-European forces” in the ascendency. “The protest against the establishment”, he added, “is expressed in liberal values.”

There was something in this expression of Scottish exceptionalism but, at the same time, Mr Salmond’s presentation of his party’s success as outwith the new normal made the mistake of assuming that populism can only be right wing.

As the academic Jan-Werner Muller argues in his new book What is Populism?, given that during 2016 both Donald Trump and Bernie Sanders were called populists, it isn’t really a coherent political philosophy but more a set of distinct claims with what one might call an “inner logic”. Usefully, Mr Muller attempts to pin down precisely what constitutes a populist, and although he overlooks Scotland, there is much (though not all) that can be applied to the SNP over the past decade. First, being critical of “elites”, as many populists are, is a “necessary but not sufficient” condition, for most politicians do that at some stage; more typical is the claim “that they, and they alone, represent the people”.

All parties do this to some degree, claiming to “stand up for Scotland” but the SNP arguably goes much further, promoting the idea of a single, homogenous Scottish “people” with shared interests and goals, while delegitimising opponents as “talking Scotland down”, “Red Tories” and often, by implication, somehow not proper Scots. Nor does populism end after an electoral victory. As Mr Muller points out, opponents like to believe populists will fail in office but usually they do not. The Unionist parties thought the SNP would crash and burn in 2007 but nearly a decade later it’s still Scotland’s most popular party.

Mr Muller argues that, in government, populists generally hijack the apparatus of state, indulge in “clientelism”(that is, trade material benefits for political support particularly among the middle classes) and suppress civil society. Despite histrionic claims to the contrary, the Scottish Government hasn’t really done any of those things, although it does have a tendency to harass critics, another standard trait.

Populists also tend to pursue policies that yield short-term electoral benefits but little long-term gain, for example the SNP’s 2007 pledges to reverse NHS closures and eradicate student debt, promises that were either counterproductive or undelivered in office. As Mr Muller observes, populism is often associated with the “oversimplification of policy challenges”, which the SNP is guilty of.

What’s curious about the SNP is that it is both populist insurgent and “liberal elite”. There’s a tension in this. Nicola Sturgeon came close to acknowledging as much in her recent speech to the Irish Seanad, recognising that it wasn’t enough to “assert the benefits” of a “progressive, liberal democracy” but also “to demonstrate the benefits of these values”. As the journalist Jamie Maxwell observed, if the First Minister’s analysis is correct, there will come a point when the SNP has to decide “whether it represents part of that [established] order or an insurgent challenge to it”. The draft Budget rather suggests it’s more comfortable being the former.

As Mr Muller writes, populists in government can continue to “behave like victims”, with majorities acting “like mistreated minorities”. Thus failures in government are blamed on others, usually distant elites who naturally do not and cannot “truly” represent the people. Besides, the populist claim to truly represent the nation or its people persists regardless. In the 1980s, for example, the SNP claimed to be “Scotland’s party” even when it barely managed to poll in double figures because, as Mr Muller observes, “their claim is of a moral and symbolic – not an empirical – nature, it cannot be disproven”.

And there is what he calls the “final great irony”: populists in government usually end up behaving just like the “old establishment” they’ve swept away. So while Donald Trump promised to “drain the swamp” of Washington, he’s busy maintaining it and, while the SNP railed against Blairite pragmatism in opposition, it now vigorously pursues its own brand of Third Way triangulation.

Pointing that out makes little difference for populism is about making what Mr Muller calls “a certain kind of moral claim”, and thus it’s generally “immune to empirical refutation”. As the author put it elsewhere, arguing with populists, particularly populist nationalists, is a bit like “trying to play chess with a pigeon”. Even if you win within the rules, the pigeon will “clutter up the pieces, and finally it will s*** on the chessboard, leaving you to deal with the mess”.

Anyone who’s wasted hours attempting to engage with the faithful online will recognise that simile; the goalposts shift constantly and even clear points of empirical reality are rarely, if ever, conceded. Even Ms Sturgeon isn’t beyond arguing that black is white, for example when it comes to the Government Expenditure and Revenue Scotland figures. This makes combating populism of any variety extremely challenging. In the conclusion to his book, Mr Muller tentatively offers some guidance. “Proper argument and evidence” can still, he argues, “make a difference”, although the rise of populism ought to force defenders of liberal democracy “to think harder about what current failures of representation might be” while also pushing them to “address more general moral questions”.

It seems UK Labour strategists are planning to re-launch Jeremy Corbyn as a left-wing populist in early 2017, the intention being to harness the anti-politics mood in Brexit Britain and thus narrow the considerable gap between it and the Conservatives. If another aspect of populism is attracting large turnouts at political rallies, then the leader of the Opposition qualifies, as does president-elect Donald Trump and First Minister Nicola Sturgeon.

If Scottish Labour had any sense, it would take this on board while emphasising the SNP’s “10 wasted years” as we approach the local government elections in May next year (it worked for Harold Wilson in 1964, although then it was “13 wasted years”). It might also mount an assault on increasingly baseless perceptions that the SNP has been “competent” in devolved government.

At the end of the day, as Mr Muller writes, populists are just different elites trying to grab (and then retain) power with the help of “a collective fantasy of political purity”. In reality, however, most politicians are much the same, although populism can succeed in disguising that inconvenient truth to a remarkable degree.