The Logic of Proportional Representation

I commented last week on the Scottish local council elections. As it turns out, the results in Stirling were rather interesting: SNP: 9, Labour: 8, Conservative: 4, Green: 1.

No party had a majority (over half of the 22 seats). But in today's news I see that the Labour and Conservative Parties (12 seats between them) have agreed to enter a coalition. (This makes a change from the SNP minority council that's been in charge from 2008 until now.)

I was struck by the reported reaction of the SNP:
"Graham Houston of the SNP ... said: "The people of Stirling will be shocked that the Tories and Labour will get together to form an administration on Stirling Council, despite neither party being the biggest party after Thursday's election ... The real losers will be the people of the Stirling Council area, who after rejecting Labour at the ballot box will nonetheless see Labour entrenched at the helm of Stirling Council ... The people of Stirling will rightly feel betrayed by this treacherous Labour/Tory alliance.""

It seems that this statement is either downright misleading or portrays a lack of understanding of the electoral system. The elections were held under STV, a form of proportional representation. The simple idea is that the party or parties with a majority of seats thereby represent the majority of voters.

Ok, it's true that no one voted for a Labour-Conservative coalition, but the Labour and Conservative councillors between them represent more people than the SNP alone. It's not clear in what sense he can say that the people of Stirling rejected Labour, except in so far as Labour failed to win a majority, but that is true also of the SNP.

Simply being the largest single party does not give one the right to govern. Suppose we had one centre-right party with 40% support and two centre-left parties each with 30% support. Here we should expect the latter two to form a coalition government and, in doing so, they would be representing the majority of the people.

Disclaimer: I don't know the exact breakdown of the vote in Stirling, nor how the redistribution of preferences went to arrive at the final outcome, but the difference between SNP (9 seats) and Labour (8 seats) could be negligible. Even if it's not, the above points still stand. Proportional representation is intended to realize majority rule, whereas non-proportional systems of representation allow sizable minorities to wield disproportionate power.