This Scottish election has left Yes voters with a serious dilemma

They often make use of models and best practices from other countries. However, the multitude of relevant parameters usually precludes simple copy and paste techniques. Institutional imports tend to leave considerable room for unintended and often also undesired consequences. With the emergence of Alex Salmond’s Alba Party, it looks as if the Scottish electoral system will be cited by generations of political scientists as a prime example of how such an undesired outcome is produced. Or will it?

Scotland has a so-called mixed member proportional (MMP) electoral system, where some seats are won in single-member constituencies via the plurality system and some via a proportional regional list system that compensates (to some extent) for the disproportionalities in the plurality vote.

The system was modelled on a similar one used in Germany and New Zealand that is often praised as representing the best of all worlds, combining proportionality (ie fairness) with party system concentration (ie governability).

And indeed, with regard to proportionality Scotland takes pride in performing much better than the apparently anachronistic and unfair first-past-the-post system at Westminster (even though it does not reach German/NZ figures).

At the time, the decision to introduce MMP resonated quite well with the “new politics” idealism of the pre-devolution era. However, as we know by now, the major reason behind its introduction was to prevent an overall SNP majority. It was designed as an institutional safety net against the potential slippery slope towards independence.

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What was not known and thus not discussed at the time, was that MMP systems have one major flaw. They have a high propensity to being “gamed”, to use the First Minister’s term. Scholars have revealed a number of examples in countries as different as Italy, Venezuela, Lesotho and Albania where major parties used different forms of strategic “collective split-voting” in order to eliminate at least part of the adverse effect the compensation process would have had on them.

Running some or all of their candidates under different labels in the two distinct electoral arenas or actively encouraging a list vote for allied minor parties handed them a disproportionately high number of seats. As a result, some of these parties and coalitions gained exaggerated supermajorities, effectively turning the electoral system impact on its head.

Alex Salmond’s recent intervention constitutes a rather new form of collective split-vote strategy. In contrast to the international examples referred to above, it is not the majority party itself that seeks to take advantage of the system’s loophole, but a rival one that is claiming to make better use of the votes that would be “lost” if cast for the party dominating the constituency vote.

In normal circumstances, such a claim would be perceived as a rather unconvincing, obvious con. It is only because of the unfettered predominance of the independence question that it can be taken seriously at all. For, despite all the complexities of Scottish elections, this manoeuvre has at least the theoretical potential to provide an artificially enlarged majority for the independence parties (SNP, Greens and Alba). Designed as a safety net against independence, the Scottish electoral system may well become its major catalyst.

Whether this really works obviously depends on the Scottish voter and the specifics of the Scottish electoral system. In order to show Alba’s potential effect, I have looked at a couple of scenarios in detail, in each case starting from the 2016 election results. Let us first assume that all SNP votes for the regional list are transferred to Alba. Of course, this is not a likely outcome, yet it helps us to locate the upper limit of the split vote strategy.

In such a case Alba would win 34 regional list seats to become the second strongest party in the Scottish Parliament. Together with the 59 constituency seats of the SNP and the one list seat the Greens would keep in Lothian this would accumulate to 94 seats or 73% of all seats for the three pro-independence parties.

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This clearly constitutes the supermajority Salmond was speaking of. The calculation becomes more complicated if we assume Alba will take away only parts of the SNP vote. An optimistic estimate of a

20-percentage-points transfer would still result in a supermajority of 81 seats (63% of Holyrood seats) with the SNP on 59, Alba 19 and the Greens three. A less optimistic scenario would put Alba at 14% (for the sake of simplicity all deduced from the SNP), the current popularity rating of Alex Salmond amongst Scottish citizens.

OF course, not all Salmond supporters will cast their vote for the new party. However, this gap might be more than compensated for by two groups of voters who dislike Salmond yet might still be tempted to give their second vote to Alba – disgruntled SNP voters who have nowhere else to go and independence activists accepting the seat maximising argument.

In this case, such a vote distribution would have almost the same outcome as the 20% estimation: SNP 60, Greens three and Alba 16 – a clear majority for the independence parties, yet no majority for the “auld alliance” of SNP and Greens.

This could be seen as a strong signal to the UK Government and the international community. However, personal animosities and strategic differences with Alba would also seriously infringe on an SNP government’s capacity to deliver on their policy preferences, including the second referendum.

According to my modelling, an important threshold emerges between 5-%. A six-percentage-points transfer from the SNP to Alba still sees the latter to be indispensable for an independence majority, while a five-percentage-point deduction or less would produce a majority for SNP and the Greens.

This even holds if we assume the transfer comes from the SNP and the Greens, although their majority would then be even further squeezed to a razor thin margin of one or two seats. Based on the 2016 results, however, there is absolutely no scenario where a transfer of independence votes to Alba would prevent a pro-independence majority.

At first sight, this may look very comforting for independence supporters. However, it comes with a huge caveat, as it is heavily dependent on the 2016 benchmark. If the SNP drop only one or two constituency seats and/or the overall share of independence votes on the list falls slightly, the picture changes dramatically. Three independence parties fighting for the same reduced space would significantly increase the possibility that a transfer of less than six percentage points to Alba would deduct seats from the SNP and/or the Greens without turning them into Alba seats.

This might very well leave the SNP to form a minority government with a Unionist majority in the Scottish Parliament – hardly a base for another referendum.

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Casting your regional vote for Alba could thus facilitate highly different outcomes depending on other voters rationale. If it is done by large chunks of SNP voters, it will most probably lead to an independence supermajority, with a Scottish Government tied to the pivotal Alba party. This is clearly Salmond’s favourite result. If the transfers are marginal and/or the SNP are outperforming their 2016 result, the SNP are back with a majority, while Alba might not even win a seat – a clear favourite for Nicola Sturgeon.

Any seats Alba would still win in this scenario would boost support for independence in the Scottish Parliament without necessarily restricting policy and strategic options for the Scottish Government.

While this might still cause a headache for the First Minister, it is the last scenario that would accelerate her pain to intolerable levels: a small transfer from SNP and Greens to Alba, in conjunction with a slight decrease of votes for both of them, might blow the whole thing for the independence movement – a Unionist’s dream and a nightmare for both Alex and Nicola.

In the current context, the widely praised MMP electoral system poses a real dilemma for pro-independence voters: without knowing how other voters behave, their individual vote for Alba may inadvertently contribute to their worst-case scenario.

Klaus Stolz is a political scientist and Professor for British and American Studies at Chemnitz University of Technology in Germany