 The necessity argument proceeds by stipulating that entrenchment is reflected in degrees of disbelief. This connects an agent’s updating behavior with her ranks for various propositions. Recall that Bayesians stipulate a similar connection between degrees of belief and acceptable betting ratios. Equipped with this connection, Huber (2007, 2020) proves that if an agent fails to validate the ranking calculus then, were she to encounter independent, mp-reliable information sources of various kinds, her beliefs would fail to be deductively cogent. That completes the necessity argument.