Few sentences in the philosophy of probability have generated more confusion than Bruno de Finetti’s famous claim that “probability does not exist”. The line is routinely interpreted as a denial of probability itself, while de Finetti intended only to reject the idea that probability is an objective property of the world. A recent essay by David Spiegelhalter in Nature has reintroduced this ambiguity through an instrumentalist “as-if” formulation. This short note clarifies the distinction between de Finetti’s anti-metaphysical stance, Spiegelhalter’s pragmatic instrumentalism, and E. T. Jaynes’s conception of probability as a form of epistemic objectivity. Recognising these differences helps avoid persistent misunderstandings about what ‘non-existence’ means in probabilistic contexts.
Tommaso Costa (Mon,) studied this question.