In his book The Blank Slate, Steven Pinker makes an interesting point about the fact that our brains haven’t evolved to intuitively grasp probabilities. It is an acquired skill like reading, not something innate like walking.
This can lead to scenarios like this:
Some experts are describing the risks of accident at some nuclear waste storage site. They describe various conceivable sequences of events that could lead to failure. For example, accidental drilling in the wrong place, erosion, undetected cracks in the rocks, which could lead to groundwater contamination. Then natural water movement, or volcanic activity, or a large meteorite impact could damage the site and release radioactive materials in the biosphere. The experts will estimate the probability of each event, or each chain of event, and numbers like 1 in X millions will come up.
To the experts, this is reassuring. They are basically saying: “This is pretty damn safe.” But they are speaking a different language from most people.
As Pinker says:
“When people hear these analyses, however, they are not reassured but become more fearful than ever — they hadn’t realized there are so, many ways for something to go wrong! They mentally tabulate the number of disaster scenarios, rather than mentally aggregating the probabilities of the disaster scenarios.”
How to make it better
How can we improve the situation in the hope that more rational decision-taking will take place? The only short-term realistic solution seems to be education. Just like we have no innate cognitive organs for abstract mathematics or reading but still can learn to use our brains to acquire these skills, we should try to make the understanding of probabilistic thinking more widespread.
We don’t expect people who have never studied physics at all to be any good at it, so why do we expect that decision-makers (and the voters/shareholders that supports them) will be able to understand probabilities – especially in complex situations – when they weigh the pros and cons of some proposal.