The Physics of William of Ockham (review)

294 JOURNAL OF THE HISTORY OF PHILOSOPHY 25:2 APRIL 198 7 service of contemporary philosophers in a way which holds to a high standard of historical fidelity while relating the discussions to ongoing philosophical concerns. We have seen a good deal of impressionistic use of medieval texts by contemporary philosophers --a paragraph or two in translation providing a springboard for speculation of dubious historical value, whatever its philosophical merit. And there are many studies of medieval philosophy which make it a self-contained universe of discourse of little interest or apparent moment to our philosophizing. Gracia has attempted to bridge that gap and he has succeeded in a way that has put us all in his debt. One can only hope that his research has carried him into later medieval thought and that we can look forward to a sequel to this truly welcome book. RALPH MCINERNY University of Notre Dame Andr~ Goddu. The Physics of William of Ockham. Studien und Texte zur Geistesgeschichte des Mittelalters, Bd. 16. Leiden: E. J. Brill, 1984. Pp. ~43. Paper, guilders 84 . In a tried and traditional way of doing history of science, the historian appoints him/herself as a Nobel Prize Committee of one to judge if the ultimate accolade, whether the person in question made significant contributions to the progress of science, should be awarded figures from the past. Andr~ Goddu adopts exactly this role for himself, and it determines the structure of his book. He aims his explication of Ockham's physics at deciding the question of Ockham's contribution to scientific progress. Since from a modern perspective, the scientific advance to which Ockham might have contributed was the discovery of the principle of inertia, Goddu rates Ockham in terms of how much he set the stage for that principle. The last two chapters come down to a lengthy discussion of Ockham's conception of motion and how it did and did not condition later thinking. Approaching Ockham's physics with the question of his contribution at the fore, means that what concerns Goddu most is not necessarily what concerned Ockham most. In the ratings game, Goddu's evaluation is mixed, more positive than Blumenberg or Anneliese Maier, but not without reservations and certainly less enthusiastic than Duhem. Although Ockham did not rule out the theoretical possibility of a void, he failed to exploit the methodological potential of the notion of a void to imagine motion and rest in a state free of external or interfering forces. Goddu suggests that Ockham's failure to use ideal conditions to explore real conditions limited his contribution to the discovery of inertia. The book divides into two parts. In the first, Goddu argues that Ockham accepted the presumptions under which science is carried out: that one can make secure empirical judgments about the world and that the natural order is in some sense necessary. In the second part, Goddu explores Ockham's physics proper: his interpretation of the inductive method and his ideas about place and void, time and eternity, motion and infinity. BOOK REVIEWS 295 The most interesting part of Goddu's work is his use of the concept of possible worlds to analyze Ockham's position on the intuitive cognition of non-existents. Controversy has arisen over how to interpret Ockham's definition of intuitive cognition as "the cognition in virtue of which it can be known whether a thing exists or not."' On one interpretation, this passage says that the world is intuitively cognized as both positive and negative existential fields, so that I know intuitively there are books here in my office and that there are no elephants. A different reading of this passage interprets it as saying that I intuitively cognize only positive existential fields in the natural order, but since God has the power to suspend the causal order and to stand in for any secondary cause, he can cause me to have intuitive cognition of non-existents. When Ockham says that there can be intuitive cognition of a thing when it does not exist, he is merely preserving God's causal power and not asserting a negative-field theory of intuitive cognition. Goddu develops an intricate...