The Role of Natural Philosophy in the Beginning of Metaphysics

Abstract

The Role of Natural Philosophy in the Beginning of Metaphysics Glen Coughlin THIS ESSAY concerns an issue controverted in Thomistic circles, namely, whether one must prove the existence of immaterial beings in natural philosophy before one can begin the scientific study of metaphysics. By "metaphysics," I mean a science1 of being just as being (ens commune or ens inquantum ens)2 and not as restricted to some determinate sort [End Page 395] of being, such as quantified or mobile being, the subjects respectively of mathematics and natural philosophy.3 Being as such includes immaterial beings, such as separate intelligences and intellectual souls, as well as material beings, such as plants and animals.4 All Thomists hold that such immaterial things exist. But do we have to know that they exist before we begin the science of being as such? And, if so, how do we go about learning that they exist?5 My claim is the traditional one,6 that we do have to know of the existence of immaterial beings to begin the scientific study of metaphysics, and that we learn of their existence through natural philosophy.7 [End Page 396] I. Generalization We might think we can bypass the problem of proving the existence of the immaterial and go directly to metaphysics. If metaphysics is about being in common or being as being, one might think that there can be a science of metaphysics simply because we have the universal name "being," and especially because St. Thomas Aquinas and Aristotle say that in pursuing a science we should start with what is more general.8 It seems that metaphysics is not only possible right away, but ought to be the very first philosophy we study, perhaps after logic. "Being" certainly does seem to name something more universal than "mobile being," the subject of natural philosophy, for the adjective "mobile" qualifies and limits the noun "being." But there are problems with this simple position. A new science demands a new mode of definition, and mere generality does not suffice. The discussion of figures, though more general than the discussion of triangles, does not belong to some more universal science of mathematics. The division of the speculative sciences, according to St. Thomas, is based not upon generality, but upon the degrees of materiality found in the definitions of the subject-genera of the sciences.9 The reason for this is that every habit (and science is a habit of knowing something by way of a syllogism)10 is defined in terms of its [End Page 397] object.11 But the objects of science are things insofar as they are intelligible. Because intelligibility is due to removal from matter,12 the object of every speculative science is something removed from matter, and the kinds of intelligibility (and so the species of science) are determined by the kinds of removal.13 The ways in which the sciences differ per se, then, is by the presence or absence of matter in their subject-genera. Some things have sensible matter in their definitions, like natural things (e.g., horses and dogs, rocks and fires, cannot be or be understood without reference to sensible qualities like color, weight, hardness, etc.); others do not, but only have "intelligible matter." Squares and rectangles, being accidents, cannot exist apart from a substance in which they inhere. That substance is then a sort of matter, but it is perceivable only by the intellect, and so is called "intelligible matter."14 Things defined with sensible matter are studied by natural philosophy, those without, but with intelligible matter, by mathematics. Those things without any matter in their definition at all (e.g., being, one, and separate substances), are studied by metaphysics.15 Here things become a little more complicated because St. Thomas gives more than one description of the science of metaphysics. Sometimes he says it concerns being as being, sometimes the first causes, sometimes the immaterial. How can it be about all three of these? It is not about all of them as [End Page 398] subjects, though it is in a sense about all of them. It is about being as being in the sense of a...