This principle says that rational initial credence should treat chance as an expert, deferring to it with respect to opinions about the outcome \(p\), by adopting the corresponding chances as your own conditional degree of belief. The New Principle—adopted to deal with some problematic interactions between Lewis’ metaphysics and the PP—advocates deferring to chance in a somewhat different way. This New Principle NP suggests (more or less) that rational initial credence should treat chance as an expert with respect to the outcome \(p\), by adopting the conditional chances, on the admissible evidence, as your conditional degrees of belief on that same evidence, as in this principle (this claim corresponds to equation 3.9 in Hall 2004; see his discussion at pp. 102–5 for some important qualifications, and the connection to the formulation of the NP in Lewis 1994):