Causa sive ratio. La raison de la cause, de Suarez a Leibniz (review)

Over the last two decades, there has been a good deal of outstanding work on the problem of causation in early modern philosophy. Some of it has been devoted to first-order questions: for example, on whether this or that thinker allows for real causal activity among finite substances (and which ones). Other studies, by contrast, have focused on second-order questions, especially the proper formulation of the causal principle itself. Vincent Carraud's book is primarily concerned with second-order questions, although it does have something to say with respect to first-order questions as well. But the depth and breadth of this study makes it much more than just another entry in the ongoing discussion over who thought what about causality among the early moderns. Carraud has a large and complex story to tell: the development of the principle of sufficient reason in the seventeenth century. In particular, he wants to know which philosophers can truly be said to have adopted that principle in its most rigorous formulation. It is both a philosophical and a historical story, and it appears in what is surely one of the most important and interesting books in early modern philosophy in recent years.

Carraud directs our attention to a particular phrase that originates with Descartes but then seems to reappear (in various forms) throughout the period: causa sive ratio, "cause or reason." Every term in the phrase is subject to interpretation, of course—'cause,' 'reason' and especially 'or'—and the thesis it embodies (and a philosopher's attitude toward it) is a function of how those terms are to be understood. Carraud's interest is in what this phrase can tell us about how a select group of philosophers (primarily Descartes, Spinoza, Malebranche and Leibniz) regard the relationship between causality and intelligibility.

The story begins with Suarez, the late sixteenth-century Scholastic. Suarez's contribution to the rise of the principle of sufficient reason is modest but crucial. He privileges efficient causation over all of the other Aristotelian varieties. While he still grants some explanatory role for formal, material and final causes, they have lost their status as "true" causes for Suarez; in fact, they qualify as causes only by analogy with efficient causation. As Carraud reads Suarez, the ratio causae belongs properly only to the efficient cause, since it alone can provide the reason for the existence and being of a thing.

It is Descartes, however, who occupies the central role—both historically and philosophically—in Carraud's story. For it is he who truly effects the ultimate reduction (or, as Carraud puts it, unicité) of causality. In the Cartesian scheme, all but efficient causes are banished. Moreover, the efficient cause of an effect is now defined as the sufficient cause, one that explains why the effect is as it is. "La primauté et l'absoluité de la cause lui viennent de ce qu'elle rend raison de l'effet . . . Les causes sont d'abord les raisons (suffisantes) des effets, en quoi elles les expliquent" (199-200). Moreover, with Descartes we find a universal application of the principle of causality to all things, even to those that previously either were not regarded as sufficiently real to need a cause (the objective reality of ideas) or were regarded as standing outside the domain of causality altogether (God). It is not that God is a caused being for Descartes. Rather, the important thing is that God is, like all existing things, subject to the causal question. That is, it is legitimate to ask why God does not need a cause. And, in Carraud's account, this is where ratio comes in to its own. God is not a caused being, but there is a reason (in God's immense power) why God does not require a cause. Moreover, the only analogy we have for thinking of the way in which God's immensity forestalls God needing a cause is in terms of efficient causality itself...