Is fanaticism incompatible with wisdom? The profound truths behind famous sayings

British philosopher Bertrand Russell's assertion that "the whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts" was an essential inclusion in the 86-year-old Australian's new book Just Saying.

There's now scientific evidence to prove that Russell was right that people who are fanatical tend to be sure of their own ideas, Mackay says.

"People who are a bit wiser, a bit more reflective, perhaps you might even say a bit more mature, realise that the heart of wisdom is doubt," he tells RNZ's Saturday Morning.

Listen to the full interview here

When Mackay's publishers told him he could choose just 25 quotes for Just Saying, this quote "went straight in without any thought", he says.

While it's too easy to describe people we disagree with as fools, there's evidence to prove religious fundamentalists, political extremists or "just people who have passionate views about football or whatever" do tend to be overly confident.

"People who are a bit wiser, a bit more reflective, perhaps you might even say a bit more mature, realise that the heart of wisdom is doubt.

"Albert Einstein, when he proposed his general theory of relativity, he didn't know whether it was actually going to turn out to be valid, whether it was going to be true. And he expressed doubt about it.

"There is recent research that confirms this proposition and shows that people who have the least qualifications or the least understanding of some opinion that they're expressing, are generally speaking, more confident of it than those who are better informed."

Most of us have only heard the "opium of the people" part of Karl Mark's quote, Mackay says, and the atheist German philosopher was, in fact, very sympathetic to the societal role of religion.

"His view was that religion was the heart of a heartless world, that it was the sigh of oppressed creatures, that the workers in their chains through history, across cultures, have needed the consolations of religion to give them hope, to give them some faith in a better future.”

Marx actually praised the role religion played in the lives of the oppressed masses, he says, and dreamed of "a religion-less world" as one where workers were freed from their chains.

"All over the world, we still have many people who are wounded, marginalised, suffering terrible deprivation and oppression, for whom religion is as important as it was when Marx was writing.

"He would be pretty horrified at late-stage capitalism, I imagine."

This ground-breaking idea by Canadian philosopher-turned-pop culture guru Marshall McLuhan radically changed the way people thought about the role of mass media in the early 1960s, Mackay says.

Up until that time, there was a "big obsession" about the effects of people being exposed to media content, in particular how televised crime might influence viewers' attitudes and behaviour.

"McLuhan swept in and said, all that content stuff is interesting, but it's trivial compared with the big question, which is what is the effect of watching television on people, as opposed to the effect of reading on people, as opposed to the effect of having a face-to-face conversation?”

The fact that receiving a handwritten letter in an envelope from someone you've only texted with is itself "a powerful message" was McLuhan's point, Mackay says, which can also apply in everyday communications.

"We've always said, choose your words carefully. That's good advice... [but also] think about the medium you're choosing to communicate your message with.

"Is this worth a phone call? Or will a text do? Do we need to be face-to-face in order to have this conversation? Or should I write it down?"

In the early 20th century, American media tycoon William Randolph Hearst "had the American newspaper industry by the throat", Mackay says.

"He had noticed that when the headlines on the front page were grim, when they were about awful disasters, storms, car crashes, rapes, plane crashes, etc, newspaper sales went through the roof [whereas] when it was just reporting on some local political matter, sales slumped.

"His explicit instruction to his newspaper editors was, 'If it bleeds, it leads'. In other words, if you can find really bad news, really grim, awful stuff, make that the headline.

"Journalists must do their job, and we do, as citizens of the world, need to know what's going on. But I do think a relentless diet of bad news does have a bad effect on our mental health, particularly for people who live alone and who are a bit socially isolated and aren't part of their local community or neighbourhood."

It's helpful for us to distinguish between news we can use and news we can't use, Mackay says.

"We need to get steamed up about news we can use. Let's be citizens of the world. Let's be well-informed about how grim everything is. But we do need to learn to keep our emotional distance, or we are at risk of having our mental health affected."

After Australian academic and public intellectual Donald Horne published his 1964 book The Lucky Country, this phrase was adopted by nationalists "as a sort of a slogan”, Mackay says.

"[The idea was] 'Look at us. We live in the lucky country,' as though that was a good thing to say.

"I suppose with our long history of gambling, the idea that luck was somehow a virtue makes a rough kind of sense, but Horne meant it as a criticism."

The Lucky Country was actually a scathing criticism of Australia, Mackay says, which Horne described as "a second-rate society being run by mediocre politicians and business leaders".

Horne believed that Australia had charted its course up to the early 1960s "as a matter of good luck rather than good management", he says.

"His book was a call to lift our game when it came to politics and business and culture and so on.

"I wonder what he would make of Australia now. I think he'd be slightly more complimentary."