Conspiracy theory, I said in my last standup show, is how idiots get to feel like intellectuals. I still believe this: conspiracy theory is primarily a way for people, mainly men, to appear in the know, to use their collection of assumptions, generalisations, straw men and false inferences to say, effectively: ah, the wool may have been pulled over your eyes, my friend, but not mine.

But there are other reasons why it’s so popular these days. It provides lonely men with an online community of like-minded lonely men. It’s comforting; it’s reassuring. It provides order in a disordered universe to imagine that shadowy forces organise horrific events, rather than to have to confront the terrible truth that death and destruction happen, all the time, apparently at random. And, as David Cameron pointed out this week in his speech on extremism, it creates a way into something else that’s becoming increasingly popular these days: antisemitism.

The conspiracy theorist is, of course, the good guy, the lone hero, unmasking the secret powers of evil

Why do so many conspiracy theories boil down to: it’s the Jews wot done it?

One simple reason is that Jews are quite hard to spot, compared with most minorities. This allows them to be unmasked, and unmasking – to be able to say, “I and no one else (apart from all my mates on abovetopsecret.com) have spotted something hidden” – is the principal drive of the conspiracy theorist. But more importantly, within racial stereotyping Jews occupy a somewhat unique position, with a two-pronged status – both low and high.

Although they can be described as stinking and dirty and vermin, and all the other unlovely appellations ascribed by racists to every ethnicity outside the mainstream, they are the only minority who are also secretly in control, pulling the strings behind the scenes, forever conspiring to promote their own hidden global agenda.

This doublethink, which has existed more or less since we made the silly mistake of preferring Barabbas, has in our own time been turbocharged by the existence of the state of Israel. Those who have always felt that Jews were powerful, controlling and out to destroy the world can now point in the direction of the Middle East and say: there you are.

But for the conspiracy theorists, even the most appalling political and military machinations of Binyamin Netanyahu and the Israel Defence Forces – of Israel itself – are far less important than the creation of what David Aaronovitch, in Voodoo Histories, describes as a new kind of super-Jew: the Zionist. This is not, for the conspiracy theorist, the straightforward hate figure of the left. Rather, it is a character, or more importantly a group, to which all western governments are secretly in hock: unbelievably rich and powerful, and dedicated unswervingly to its own project, which is nothing less than the complete control of the world. Yes: Zionists are basically Spectre.

Which makes the conspiracy theorist, to some extent, James Bond. So many conspiracy theories end up in some way to do with these particular imagined super-villains – even ones such as the “murder” of Princess Diana, which seem to have very little apparent benefit to the Zionists – that it’s clear some kind of antisemitism, even if unconsciously, is going on here. But that’s obscured by the self-image of the conspiracy theorist, who is, of course, the good guy, the lone hero, unmasking the secret powers of evil – even if unmasking the secret powers of evil in so many cases seems to involve saying: it’s the Jews.

If the conspiracy theorist is the good guy, this cannot be bad; therefore it cannot be racist. So we come to a position whereby for a lot of people, pointing at one small ethnic group and saying they’re responsible for all the worst things in the world is no longer racist. It’s fighting the good fight.

I’m talking mainly about how things are among the slightly absurd men on social media trading reasons for why the moon landings were actually faked (by the Zionists, I assume: Stanley Kubrick was Jewish – he probably filmed it). In the Middle East and much of east Asia, beliefs such as the idea that 4,000 notified-by-Israel Jews didn’t turn up for work in the World Trade Center on 9/11 (a fallacy: 9.25% of people who died in the Twin Towers were Jewish, roughly in proportion to the Jewish population of New York City) are, for many people, facts.

Our culture moves very fast now. When complicated and troubling events happen, easy answers are quickly sought and provided. There is an American standup I once saw whose first line went: I blame the Jews – it’s quicker that way.

Having said this, I have no idea how, without intense curbs on free speech (which won’t work – conspiracy theorists love the martyrdom of being muzzled), David Cameron will change anything. And frankly, if he tried to convince me that the world wasn’t actually controlled by a rich and powerful network operating on behalf of their own secret political and economic interests, I wouldn’t believe him either.

• David Baddiel’s new work-in-progress show, My Family: Not the Sitcom is at Soho Theatre, London from 5–8 August

• This article was amended on 23 July 2015, to clarify a sentence through the addition of the words “in proportion to”.