William of Ockham, an English Franciscan friar born around 1287, was denied the rank of regent master at Oxford, summoned to the papal court at Avignon on suspicion of heresy, and then concluded that the pope himself was the heretic. This episode follows his escape from Avignon on the night of May 26, 1328, his excommunication, and his refuge in Munich under Emperor Louis of Bavaria, where he spent the rest of his life writing against papal power.

Along the way we unpack the ideas that made him dangerous: the principle of parsimony now called Ockham's Razor, his nominalist attack on universals like tree-ness, his separation of theology from science through voluntarism (including the famous donkey argument), and the apostolic poverty dispute over whether a monk owns the bread he eats. We also cover his early theories of the social contract,  ...