Francis of Marchia and William of Ockham: Fragments from a Dialogue

After discussing Francis' rejection of Ockham's theory of quantity, this paper shows how Francis' Improbatio became a source for Ockham's Opus Nonaginta Dierum. Building on Offler's ground-breaking critical edition of the latter work. it is argued that Ockham made extensive use of Francis' Improbatio, even though on several points he felt it necessary to reformulate the arguments of his confrère or even to substantially modify his positions. The two Franciscan theologians differed deeply both in their basic philosophical commitments and in their methodological attitude. These differences emerged even when thay were - so to speak - fighting on the same front.