Eamon Duffy on Papal Power
Here is an interesting passage from Eamon Duffy's Saints and Sinners: A History of the Popes (New Haven: Yale University Press, 1997; revised edition 2001):
A crucial influence in the development of the idea that the Pope himself might be free from error came from the Franciscan debates about poverty. Successive popes had ruled in favour of the Franciscan rejection of property. When Pope John XXII repudiated that teaching, and denied that Christ was a pauper, Franciscan theologians appealed against his judgment to the infallibility of other, earlier popes. They argued that the Church, in the person of those popes, had repeatedly accepted the Franciscan view of poverty as an evangelical form of life. John XXII, therefore, was in error in rejecting this infallible teaching--and since true popes do not err, this proved that he was no longer a true pope. Papal infallibility was here being invoked not to exalt the Pope's authority, but to limit it, by ensuring that a pope did not arbitrarily reverse earlier Christian teaching.