Bayesianism is the broader philosophy inspired by Bayes' theorem. The core claim behind all varieties of Bayesianism is that probabilities are subjective degrees of belief -- often operationalized as willingness to bet.
See also: Bayes theorem, Bayesian probability, Radical Probabilism, Priors, Rational evidence, Probability theory, Decision theory, Lawful intelligence, Bayesian Conspiracy.
This stands in contrast to other interpretations of probability, which attempt greater objectivity. The frequentist interpretation of probability has a focus on repeatable experiments; probabilities are the limiting frequency of an event if you performed the experiment an infinite number of times....