HERE’S a remarkable fact: the police in Scotland holds a list of flags which it could be a criminal offence to display in public, and the list includes the Irish tricolour, the Israeli and Palestinian flags and the Catalan flag. But here’s an even more remarkable fact: academics with an interest in flags contacted by my colleague Peter Swindon to comment on the list were too scared to talk publicly because of the death threats they have received in the past. This is, I’m afraid, how flags work: they start with pride and end with hate.

I’ve experienced a little bit of the hate myself. In 2013, I wrote a column about the saltire, in which I expressed my disquiet about the flag, its association with nationalism, and how it was being used in the lead-up to the 2014 referendum. Almost immediately, the column provoked hundreds of abusive, angry and anatomical emails, calls and online comments. There were a few more light-hearted responses it has to be said ¬– one chap sent me a big cardboard box full of saltires – but on the whole the reaction was hair-raising: I should be ashamed of myself, they said, I wasn’t a true Scot, they said. I wasn’t one of us.

At the time, I tried to let all of it wash over me, but the reaction to The Herald on Sunday’s story about the police list of flags has reminded me of the kind of emotions that can centre on national symbols. In response to the article, readers said Police Scotland’s list was outrageous, shameful and Orwellian, and indicative even of a police state. The lawyer Aamer Anwar, who represents the Catalan politician Clara Ponsati, also said the idea that flying a national flag could be construed as a criminal offence was a step too far. “My concern,” he said, “is the impact on freedom of expression and the right to identify with struggles for freedom internationally – surely that should not be made a crime in a democracy?”

I have to say I think all of that is an over-reaction and a denial, perhaps, of the fundamental nature of flags. The document issued to officers includes pictures of the potentially problematic flags (they do not include the saltire or the Union flag) and explains that their display can be a breach of the peace or an offence under the Criminal Justice and Licensing (Scotland) Act 2010. However, the document also makes it clear the law is only broken if the flags are flown in a provocative manner, which means context is everything. No one is saying that flying certain flags is illegal per se, only that the police can intervene if they are flown in a way that could provoke unrest.

This seems to be a perfectly reasonable position and an acknowledgement of the political and cultural realities in a country like Scotland where football, religion and the politics of independence are so divisive. However, the fact the list exists – and needs to exist – is also a consequence of the intrinsically troubling nature of flags. It’s simple really: a flag encourages people to identify with the thing it represents (a nation, a political cause, whatever) and the inevitable next stage from that is you label people who identify with the flag as good, or one of us, and everyone else as bad or one of them.

Loyalty to a flag also leads to distorted thinking in other ways. The other day I spent the afternoon with the novelist Christopher Priest, who has moved from Devon to live on Bute. Mr Priest said he and his partner left England partly because they were disturbed by Brexit and what they saw as the increasingly nationalist atmosphere there. “In Devon, people had UKIP flags,” he told me. “So I said, we don’t want to be in England any more. Something horrible is going on.”

Now I did point out to Mr Priest that if he wanted to escape nationalism, perhaps Scotland wasn’t his best choice, but his new novel, An American Story, is very interesting on the subject. He imagines a Scotland of the future that has made a unilateral declaration of independence and has identity checks at the border with England, but the book also plays around with the Tomas Theorem, a sociological idea which says that people do not act according to the facts but their interpretation of the facts.

This helps explain the power of flags: people believe in a certain cause, defined by a flag, and this, rather than anything more objective, then guides their actions and responses. As Police Scotland’s flag list points out, it can even lead to yet more flags – when the Israeli flag is waved by loyalists, for example, or the Catalan flag is flown by Scottish nationalists. It’s the symbol first and everything else flows from it; and in the end you become loyal to the flag rather than the facts.

I used to think that some flags might be more prone to these effects than others and in my 2013 column argued that the Union flag was different. I explained a little of my own relationship with the flag, starting with memories of waving it while sitting on the shoulders of my (republican but open-minded) father when the Queen visited Aberdeen during the Silver Jubilee in 1977. I admitted that I felt more inclined towards the Union flag than others because I felt more inclined towards a union of nations rather than independence. I even argued that the Union flag could represent something positive in a way other flags do not.

I now think I got that wrong and, four years on from the independence referendum, have come round to thinking that all flags, no matter what the colours, have trouble stitched into them. Even the seemingly benign rainbow flag, which represents the gay community, isn’t immune, meaning that extra letters have had to be added to LGBT to include groups that felt excluded - because it’s what flags do: they include some and exclude others and that spells trouble.

The only hope – given that flags aren’t going anywhere in modern Scotland – is for all of us to do what we can to resist their unpleasant influence. A nationalistic urge is perhaps a part of all us – and who knows, my father probably encouraged mine when he lifted me up on his shoulders for a better view of the Queen in 1977. But shouldn’t our responsibility be to resist the urge? Shouldn’t we recognise that our tribal instincts are unreliable and make allowances for them? Shouldn’t we rely on the facts rather than a fluttering symbol? In other words, isn’t it time to put away the flags?