 from chance to any type of objective probability. PP says that your credences in propositions should conform to what you take to be their chances of being true, and, admissibility issues notwithstanding, it is hard to deny that there exists a domain in which the Principal Principle is compelling, and surely one where the generalization to any type of objective probability is too. If so then the answer to the question what the subject’s credence in q ought to be in light of her consideration of information about her reliability is: