Probability is the wrong way to think about risk. When Alex Honnold free solo climbed El Capitan with no safety equipment, that was incredibly risky, despite Honnold’s extreme skill and experience making it unlikely he’d fall. Philosopher Duncan Pritchard, author of the recent book Tempting Fate, argues that we should instead measure risk in terms of fragility – how easily a catastrophe could occur. We have to learn to make high risk decisions in our lives, as a life of caution is often one of regret. Understanding risk allows us to do this without tempting fate.

My mother, who passed away recently, had a lot of sayings, one of which was that “you should never tempt fate.” What she meant by this could be summed up by one of her other sayings: “hubris begets nemesis.” If you are arrogant and overly confident in your plans, then rest assured that this will be noticed by the Gods and you will incur their wrath. That all seems right to me.

There is, however, another meaning of tempting fate that is especially relevant to taking risks. When it comes to risk-taking, you can’t be assured that everything will work out. Things can go pear-shaped. That’s the sense in which taking risks can involve tempting fate, as one is opening oneself up to¾inviting, you might say¾catastrophe. And yet it can’t be the case that we should never take risks, as it is difficult to flourish if one is always taking the cautious path. How then do we tempt fate without hubris, without inviting catastrophe?

If you look to the standard theory of risk for an answer to this question, then I think you will be disappointed. When we assess for the level of risk, we have in mind a specific unwanted risk event that we hope to avoid. According to the probability theory of risk, the level of risk is determined by how likely the risk event is. If this probability is high, then the risk is high, while if the probability is low, then the risk is low.

For lots of cases, this proposal generates the right result, which explains why it’s so widely held. Juggling dynamite is high risk because the probability of the risk event of blowing yourself to pieces is very high. Do this 100 times and in most, if not all, of these scenarios you are no more. In contrast, juggling apples is low risk because the probability that this will get you blown up is negligible. Do it as many times as you like, and you’ll be fine. The problem is that this cannot be the full story about risk.

SUGGESTED VIEWING Danger, safety and the future With Isabel Hilton, Frank Furedi, Carol Gilligan, Paul Dolan

In 2017, Alex Honnold made the first free solo climb of El Capitan, a 3000-foot slab of rock in Yosemite National Park. This is an incredible achievement. As the name suggests, free solo climbing means no safety equipment whatsoever. It is just you and the mountain. It takes immense levels of skill and years of preparation to undertake a complex free solo climb of this magnitude. But even with all this expertise and planning, the fact remains that it is a monumentally risky undertaking. Honnold could have died at any moment on that mountain. The slightest error, and he would be falling to his death.