Statistician Denies Probability Exists

Some say that quantum probabiliities are real and physical, while other say that all probabilities are just subjective estimates of human belief. I think neither is quite right.

David Spiegelhalter writes in SciAm:

Probability Probably Doesn’t Exist

All of statistics and much of science depends on probability—an astonishing achievement, considering no one’s really sure what it is ...

My argument is that any practical use of probability involves subjective judgements. ...

At the sub-atomic level, the mathematics indicates that causeless events can happen with fixed probabilities (although at least one interpretation states that even those probabilities express a relationship with other objects or observers, rather than being intrinsic properties of quantum objects). ...

There is a limited range of well-controlled, repeatable situations of such immense complexity that, even if they are essentially deterministic, fit the frequentist paradigm by having a probability distribution with predictable properties in the long run. These include standard randomizing devices, such as roulette wheels, shuffled cards, spun coins, thrown dice and lottery balls, as well as pseudo-random number generators, which rely on non-linear, chaotic algorithms to give numbers that pass tests of randomness.

In the natural world, we can throw in the workings of large collections of gas molecules which, even if following Newtonian physics, obey the laws of statistical mechanics; and genetics, in which the huge complexity of chromosomal selection and recombination gives rise to stable rates of inheritance. It might be reasonable in these limited circumstances to assume a pseudo-objective probability — ‘the’ probability, rather than ‘a’ (subjective) probability. ...

In several of those situations, a math calculation gives a probability that is accurate to several digits. This clearly reflects an objective physical reality, and not just a human belief. On the other hand, I don't think that probability is as real as energy or momentum. Probability cannot be directly measured, but only indirectly estimated by running repeated samples.

The proponents of many-worlds theory also deny that probably exists, for other reasons. They believe that all possibilities happen in their own universes, and that it makes no sense to say any are more likely than others.