The Principal Principle Does Not Imply the Principle of Indifference, Because Conditioning on Biconditionals Is Counterintuitive

Roger White ([2010]) argued for a principle of indifference. Hart and Titelbaum ([ 2015]) showed that White's argument relied on an intuition about conditioning on biconditionals that, while widely shared, is incorrect. Hawthorne, Landes, Wallmann, and Williamson ([2017]) argue for a principle of indifference. Remarkably, their argument relies on the same faulty intuition. We explain their intuition, explain why it's faulty, and show how it generates their principle of indifference.