Physical Action, Species, and Matter: The Debate between Roger Bacon and Peter John Olivi
Abstract
In QQ.23–31 of Olivi’s Quaestiones in secundum librum Sententiarum (Summa
II) and in Bacon’s De multiplicatione specierum (DMS) 1.3, we find an intriguing discussion
concerning the link between agent and patient in accounts of physical action in
the Aristotelian tradition. Both thinkers hold that species were the link between agent
and patient; they disagree, however, about the definition and function of species.
The dispute leads the two thinkers to develop and clarify their accounts of physical
action. They discuss temporality, secondary causality, active potentiality, and the
distinction between virtual and substantial contact. This paper provides an account
of Olivi’s theory of species in medio and clarifies how it differs from Bacon’s theory.
It throws a spotlight on a significant episode in the history of philosophy, in which
Aristotelian concepts were found unsuitable to account for action at a distance and
in the interior of the patient, and hence new concepts of virtual action and species
had to be devised.