A careful study of John XXII's decree "Quia Quorundam Mentes" (1324), which was issued against some Spiritual Franciscans. The text presents: the historical background; a translation of the decree with commentary on it; a careful analysis of Brian Tierney's theory of a "gulf between the ecclesiology of medieval canonists and the ecclesiology of Vatican I"; and a discussion of the importance of John XXII for papal infallibility today.
