 Nearly a century before Ramsey, De Morgan wrote: “By degree of probability, we really mean, or ought to mean, degree of belief” (1847, 172). According to the subjective (or personalist or  Bayesian) interpretation, probabilities are degrees of confidence, or credences, or partial beliefs of suitable agents. Thus, we really have many interpretations of probability here— as many as there are suitable agents. What makes an agent suitable? What we might call unconstrained subjectivism places no constraints on the agents — anyone goes, and hence anything goes. Various studies by psychologists are taken to show that people commonly violate the usual probability calculus in spectacular ways. (See, e.g., several articles in Kahneman et al. 1982.) We clearly do not have here an admissible interpretation (with respect to any probability calculus), since there is no limit to what degrees of confidence agents might have.