Of all the hyperbole about the Additional Member System (AMS) used for elections to Scotland’s Parliament, ‘breaking the system’ must be one of the most commonly made, yet most commonly misunderstood.
The phrase is frequently coupled with the myth that the proportional AMS was a ‘fix’ by Labour to prevent the SNP ever attaining an overall majority.
‘Breaking the system’ is a phrase originally coined to refer to the unlikelihood of the SNP ever winning a majority of seats at Holyrood on— and this is the crucial point that people overlook— a minority of the vote, when it was polling in the mid 40s.
Thus, when the SNP secured a majority government in 2011 on the back of 45.4% of the constituency vote, and 44.2% of the regional list vote, its 53.5% of the seats was seen as a ‘fluke’ and unlikely ever to be repeated.
However, a comparative review of the percentage of seats won to percentage share of the vote reveals that the ‘winner’ is typically rewarded with an advantage giving them anything from 4–9% more seats than they would be entitled to under a strictly proportional system, so a party receiving high 40s actually has a strong chance of winning a majority of the seats. This is due to the nature of AMS, where mechanisms such as the top up list being regionally and not nationally based imposes an effective threshold of 5–6% which penalises smaller parties and rewards the larger ones.
The table below distils the advantage in seats that the winning party has always enjoyed:
We have seen that the loss of the SNP’s majority in 2016 can be attributed directly to the greater gap of 5% between its constituency and list percentage shares, compared to the 1% achieved in 2011. (Indeed, that bigger gap between Labour’s constituency and list vote shares led to the SNP win in 2007.)
Had #BothVotesSNP in 2016 been adhered to, with the same gap of 1% as in 2011, then the SNP would likely have doubled its list contingent of four seats and won a second majority government.
But that was then, and this is now: polling shows the SNP constituency share of the vote on or well in excess of 50%, and its list share at about 50% too.
The preconceived opinion among many is the that the ‘system is designed to prevent an (SNP) majority government’, with some believing that this is the case even if the SNP wins over 50% of the vote:
But for the SNP to win a majority of Holyrood seats on the basis of majority support, is not ‘breaking the system’ at all. It’s only to be expected, and it would in fact be impossible for the SNP not to.
Indeed, as we have seen above from a review of the historical results, the winning party is typically rewarded with at least 4% more seats than its share of the vote would entitle it to under a stricter form of PR, so an SNP victory on the back of over 50% of the vote will inevitably ensure it has an even greater majority of the seats.
The system is thus not designed to prevent majority governments at all, just to make a majority of the seats on a large minority of the vote unlikely. That said, the implementation of AMS actually makes a majority of seats on a minority (mid-high 40%s) of the vote more likely than a ‘purer’ form of PR, and this is precisely what enabled the SNP to achieve its famous result in 2011.
Commentators are therefore making wholly incorrect inferences from the unlikelihood of a party winning a majority of seats being won on a minority of the vote, and assuming that would also apply to a party winning a majority of the vote.
Some shamelessly use this false claim about the system somehow ‘preventing’ the SNP from winning a majority (typically with false claims about the SNP list vote veing ‘wasted’) to push fringe list only parties as the necessary antidote to the SNP’s ‘inability’ to win a majority.
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