This morning, via The Browser, I found a classic 1967 essay by Peter Benchley for the magazine Holiday about shark attacks. Benchley's editor encouraged him to turn his article into a novel, and the result was the bestseller Jaws, which of course was adapted to film by Steven Spielberg and became the prototypical summer blockbuster.

I was struck by the parallels between Benchley's description of how people think about shark attacks and the way we think about terrorism. Both are exceedingly unlikely ways to die, yet they have an enduring grip on our imaginations:

Irrational behavior has always been man’s reaction to the presence of sharks. Ever since man first returned to the sea, sharks have held all the terror and fascination of an ax murder.

And then near the close of the essay:

...despite the fact that a bather is more likely to be struck by lightning than attacked by sharks, there will always be something primevally horrid about the sight of the black triangular fin slipping through the waves, and something viscerally terrifying about the choked cry “Shark !”

Malcolm Turnbull's speech to the Sydney Institute last night was an appeal to reason, an attempt to argue that the threat of terrorism should not be overstated. Yet Benchley's essay is a reminder that irrational fears seem to be a permanent feature of our psychological makeup, and very difficult to shift.

Last month I wrote an op-ed for the Herald Sun on the topic of terrorism which drew on this short essay about risk perception. It argues that 'The patterns of how the human animal perceives and responds to risk have their roots in an ancient past that predates humans, and certainly predates the relatively recent development of our modern thinking brains. This may explain why we respond to risk so much more with fear than with cold factual analysis.'

So we tend to be much more fearful of rare but dramatic forms of death; of new risks that we hear a lot about from friends, colleagues and the media (what the economist Daniel Kahneman calls the 'availability heuristic'); and we tend to give more weight to the risk of catastrophic events (terrorist attacks, plane crashes, shark attacks) than chronic ones such as cancer.

There's little point arguing that the public's fears about catastrophic events are irrational; we're unlikely to be reasoned out of them anyway. But as I argued in the Herald Sun, our political leaders do have a choice to make about whether they exploit those fears or assuage them. As Turnbull argued, talk of 'existential threats' and of ISIS 'coming to get us' may just help the enemy. 'We need to be very careful we don’t...become amplifiers of their wickedness and significance.'