Probability Can’t Help You Now

Radical Uncertainty by Mervyn King and John Kay is on my reading list at present. It’s worth a read!

They give a detailed history of how probabilistic thinking evolved and works. They argue that we are a little over enamoured by the certainty probability seems to impart. We see it used all over the place. I love it in the weather forecast where there’s a probability of rain. Every now and then the forecast will say ‘a chance of showers’ with a 100% probability of rain. When you look into the details it might say 100% chance of 0-0.1mm of rain. That’s hardly any rain, but the probability makes it sound certain that I should pack the umbrella.

Kay and King suggest that probabilities make it sound as if we are more certain than we are. I love their example of crossing the road. For any given stretch of road in your area we could get the accident statistics. We could probably even break pedestrian accidents down by age and gender. There’s a high likelihood that we could identify fairly exactly the probability of you being hit by a car if you crossed this road. BUT, that probability does not help you decide when, where and how to cross the road at all. 

They caution us to be less enamoured by probability, especially when it comes to understanding uncertain situations. 

I reckon there’s a 95% chance that they are right.