This is a sort of "readers' request" post - I was asked the other day to post an explanation of how the Single Transferable Vote system (STV) works. Probably not a bad idea, because for the vast majority of us, when we go to the polls in May for the local elections it'll be the first time we've voted under that system for five years.
As long-term readers know, I spent an inordinate amount of time on this blog in the run-up to both the 2011 and 2016 Holyrood elections trying to expose a cynical propaganda campaign that was hoodwinking people into thinking that the list vote was a sort of 'second preference' or 'bonus' or 'luxury' vote. In 2011, it didn't go much further than the familiar "2nd Vote Green" schtick, but last year there was a much more concerted (I'm tempted to say ruthless) drive by the wider radical left to con SNP supporters into thinking that their party was guaranteed to win an outright majority on constituency seats alone, and that their list votes would be wasted unless given to the Greens or RISE. Bella Caledonia pushed that line relentlessly, and for one mad weekend just before the election, even the Sunday Herald was taken over lock, stock and barrel by the "split your votes" campaign.
The reality is that, in principle at least, the list vote is the more important vote because it broadly determines the overall composition of parliament. That's certainly how it played out last year after the claims of 'absolute certainty' that the SNP would clean up in the constituencies turned out to be bogus. The SNP's constituency vote increased, while their list vote fell - leading to a decrease in the SNP's overall number of seats, and the loss of their overall majority. That outcome shouldn't have been a surprise to anyone, but I suspect it was a very nasty shock to some SNP supporters (including even some SNP members) who bought into the idea that voting for their own party on the list was unnecessary. We should count ourselves lucky that the vote-splitting propaganda didn't cost us the pro-independence majority at Holyrood - it could very easily have done if more people had been persuaded to switch to RISE or Solidarity on the list, because neither of those parties were even vaguely close to winning a list seat in any region.
Having been so sorely bitten by last year's events, it's perhaps understandable that many SNP supporters are now instinctively reacting by saying "I'm only going to vote for the SNP in the local elections, and I'm not going to give a ranking to any other party". But it's really important to stress that the Single Transferable Vote system used for the local elections is completely different from the voting system used for Holyrood, and using your lower preferences for other parties is nothing like so-called "tactical voting on the list". It's literally true that using your lower preferences in the local elections cannot possibly harm the SNP in any way. At worst, it won't make any difference to the outcome at all, but at best it will help another pro-independence party to deprive a unionist party of a seat on your local council.
Some people seem to intuitively struggle with the idea that the SNP cannot possibly be harmed by using the lower rankings. I think maybe they imagine that STV is a kind of 'points system' akin to the Eurovision Song Contest - ie. if you rank Labour tenth, they'll be awarded 'one point', and that point might end up costing the SNP a seat. But that's simply not how it works. If, say, there are two SNP candidates in your local ward, and you give your first two preferences to those candidates, your lower preferences will not even be taken into account until both SNP candidates are either elected or eliminated. Your vote will not budge from the SNP column until that happens. There are no exceptions to that rule - as long as you make sure you give your top preferences to all of the SNP candidates (there may be more than two depending on which ward you live in), using your lower preferences for other parties is literally risk-free.
The best way of looking at your lower preferences is that you're expressing an opinion on who should be elected if the SNP are no longer in contention for one of the seats in your ward. If the final seat in your ward boiled down to a straight fight between the Tories and the Greens, wouldn't you want to help the Greens to win? Or would you want to effectively abstain and risk ending up with a Tory councillor? You're doing the latter if the SNP candidates are the only ones you give a ranking to.
It probably matters less whether you bother giving rankings to the unionist parties, although speaking personally I used all of my rankings in both 2007 and 2012, and I expect I will do so again this time. One way of making the impossible choice between Labour, Tory and Lib Dem is to look at which party is vying with the SNP for control of your local council. In Glasgow, for example, it might make sense on a tactical basis to rank the Lib Dems higher than Labour, because depriving Labour of a seat by any means will make it harder for them to form an administration. I expect in most cases pro-indy people will want to rank independent candidates higher than all unionist party candidates (unless the independent in question is known to be a hardline unionist themselves).
OK, a couple of extra pro-indy councillors on North Ayrshire Council isn't going to decide the constitutional future of Scotland. But as they say at a certain supermarket chain, every little helps.