Does probability exist?

For all their differences, the RCTs and the weather forecasts share one defining characteristic. They both find wisdom about the question they are wrestling with—Is this medicine going to help treat my illness? Will the hurricane cross over land on Tuesday?—through multiple simulations

Probabilistic thinking is essentially trying to estimate, using some tools of math and logic, the likelihood of any specific outcome coming to pass. It is one of the best tools we have to improve the accuracy of our decisions.

This is one of the crucial lessons of probability. Good decisions—as measured by the underlying probabilities—can turn out badly. And bad decisions—like spending $1 on the Illinois lottery—can still turn out well, at least in the short run. But probability triumphs in the end.

By risk he meant situations where we know the set of possible future events and their probabilities. In contrast, he used uncertainty to refer to situations where we don’t know the probabilities of future events. Under what he called true uncertainty, we may not even be able to imagine all possible future events.

a large part of human belief about future events rests on the frequency with which they or similar events have occurred in the past.

This is what physicist Max Planck (the father of quantum mechanics), Einstein, and others observed: No matter how much you know, there is an infinite amount of chance and randomness in the universe.