Driving back from Oxford on the A40, I spy a web address neatly spray-painted along the flank of a bridge I’m passing under. This, I think, is what comes of a limitless online forum: why bother to boil your thinking down to a graffiti-friendly exhortation when you can just direct people to your blog for more information?

The website, it transpires, was intended to publicise the issue of chemtrails. If you are entirely unfamiliar with chemtrails, I am sorry to be the one effecting an introduction – unless your idea of a fun afternoon is watching YouTube videos of unremarkable clouds accompanied by hysterical voiceovers, in which case this is the conspiracy theory for you.

Chemtrail conspiracists believe the US military is secretly attempting to engineer American weather by spraying chemicals at high altitude, and point to long skinny clouds in the sky as evidence. You can say anything you like about this contention other than “but those are just condensation trails from passing aircraft”. They have an answer for that. They have a lot of answers.

They will tell you ordinary condensation trails don’t behave that way (they do) or that they never hang around for that long (they do). Chemtrail-haters sometimes stand in their gardens spraying vinegar into the air in order to dissipate trails six miles above their heads. I know people need to believe in something, but why on Earth would you choose this?

Dark arts of the sceptic

In Joshua Ferris’s Booker-shortlisted novel To Rise Again at a Decent Hour, the protagonist, a dentist, is faced with a patient who refuses to accept the existence of the three cavities that show up on his x-ray, saying he doesn’t feel as if he has cavities. The dentist explains that’s what the x-ray is for – to show what you can’t feel. “That might be your way,” says the patient, “and that’s fine, but it’s not my way.”

I’m reminded of this passage a few days after finishing the book, when I find myself on another car journey – in the back this time – arguing passionately against the existence of mermaids. It’s not something I actually care passionately about, I’m just alarmed that I know an adult who believes in mermaids. He is, of course, a sort of conspiracist – you can’t argue in favour of the existence of mermaids without alluding to powerful forces seeking to suppress evidence of them, because you need an explanation for the lack of evidence.

I don’t have any real proof of the nonexistence of mermaids, but I do have a phone. I quickly find the deeply unconvincing mermaid documentary my friend keeps referring to. Then I find reference to the makers of that documentary admitting the whole thing was a hoax.

“I understand what you’re saying,” says my friend. “But I still believe.” He calls me a sceptic, but it’s the conspiracists who are the real sceptics. They’re the ones who refuse to accept the Wikipedia entry for “chemtrail conspiracy theory” as the whole truth. I’m so complacent that I didn’t even read all the way to the end.

I wish I could say that my unrelenting mermaid-denial springs from a lifelong commitment to the truth, but it’s really part of a deep-seated and unattractive need to spoil other people’s fun.

Tale of two Vinces

I went to the 2013 Liberal Democrat conference – my first ever – which was also held in Glasgow, so this week’s coverage has dredged a lot of repressed memories. I mainly remember the omnipresence of Vince Cable. I’d see him in the lobby, in cafes, on television. The fringe schedule listed him as attending several events simultaneously. Once, when I was walking down a lonely corridor, he passed me. Twice. I think he had a different tie on the second time.

Eventually I confessed my theory to a delegate: I told her I was pretty certain there were two Vince Cables. She didn’t deny it.