Facing uncertainty, the mind informs its owner that the odds are 50:50, even when it knows better.
People are more sensitive to changes in probabilities when they are near the boundaries of either “no chance” or “sure bet.” Moving from 0% to 1% seems much more significant than rising from 20% to 21%. At the extremes, the mind tends to move odds towards even.
Uncertainty also has a compression effect on probability estimation. When unsure, the mind mystically convinces itself that the odds are closer to 50:50 than known information indicates.
“People are often aware of their own cognitive noise, which induces cognitive uncertainty: subjective uncertainty about what the optimal action or solution to a decision problem is. Cognitive uncertainty induces people to shrink probabilities towards a simple ignorance prior.” ~ German economists Benjamin Enke & Thomas Graeber
The more uncertain people are in their judgments, the more likely they are to hedge their bets. Insurance companies successfully pitch fear for this very reason.
Figuring something faces even odds is a tacit admission of not knowing.
References:
Benjamin Enke & Thomas Graeber, “Cognitive uncertainty,” (15 November 2019).
“Why are people attracted to 50:50 probabilities?,” The Economist (12 December 2019).