Risk versus Uncertainty

I have read the book Radical Uncertainty: Decision Making Beyond the Numbers by Mervyn King & John Kay. As the title suggests, it talks about radical uncertainty. What is uncertainty? Its definition is simple: any uncertain knowledge. But there are two types of uncertainty:

·         Risk: Measurable or resolvable uncertainty. Probability calculations can be applied. Example: the outcome of a roulette or lottery game. Problems of this type can be called puzzles. Phenomena of this type are stationary (their properties do not change over time).

·         Radical uncertainty: Uncertainty that is not measurable. It arises when there is obscurity, ignorance, vagueness, ambiguity, ill-defined problems, lack of information. It cannot be described by probability calculations. Problems of this type can be called mysteries. Phenomena of this type are usually not stationary.

The weak anthropic principle: Are we alone in the galaxy?

Allen Telescope Array in the SETI project

In its initial formulation, the weak anthropic principle says that, although the appearance of intelligent life on a planet may be very unlikely, the Earth must meet all the conditions, since we exist. We know that the Milky Way contains about 10¹¹ stars. At least one (the sun) has a planet populated by intelligent life. It looks like the probability of this happening should be equal to or greater than 10^-11. Note that the weak anthropic principle does not say what the value of that probability might be.