Probability does not exist
Andrew Noble Founder & Systems Builder | Creating tensegrity for your practice
This provocative quote is by the Italian statistician and probabilist Bruno de Finetti.
It encapsulates the core idea of Subjectivism or Bayesianism, a major school of thought in probability.
De Finetti argued that probability is not an objective property of the world (like mass or temperature). Instead, it’s a measure of an individual’s degree of belief about an uncertain event, based on their knowledge and evidence.
Essentially, he meant that a “50% chance of rain” doesn’t exist in the clouds themselves; it exists in the mind of the meteorologist who assigns that value based on the data they have. It’s a powerful statement that reframes probability as a tool for reasoning under uncertainty, rather than a feature of physical reality.
