And yet any numerical probability, I will argue—whether in a scientific paper, as part of weather forecasts, predicting the outcome of a sports competition or quantifying a health risk—is not an objective property of the world but a construction based on personal or collective judgments and (often doubtful) assumptions. Furthermore, in most circumstances, it is not even estimating some underlying “true” quantity. Probability, indeed, can only rarely be said to “exist” at all.
That right there is a nice distinction in the 2 branches of the philosophy of probability: Frequentism and Bayesian. Frequentists argue that the probability is an objective property of the world, while Bayesians consider it as a subjective belief.
This brings another good clarification on the matter of Frequentism and Bayesianism.