 This is made possible by the second factor, that (un)reliability is expressed here as an objective conditional probability, and coherence alone does not dictate how subjective and objective probabilities must relate. This is analogous to the reason that the approach via the maximally rational subject above was able to represent a state of self-doubt as coherent, namely, that in evaluating my own P I compare it to a different probability function. However, in this case the second function is not an expert function that declares unconditionally what value the maximally rational subject’s value for q would be, but a calibration function, a conditional probability that tells one what objective probability is indicated by one’s subjective probability. One difference between the two approaches is that there are obvious ways to investigate calibration curves empirically, whereas it would be hard to recruit enough maximally rational subjects for a statistically significant study so we tend to be left appealing to intuitions about what seems rational.