SOURCES FOR THE SCHOLASTIC DEBATE

At least two issues contributed to the extensive discussion of essence and existence by Latin thinkers in the thirteenth and early fourteenth centuries. First, there was a need to explain the metaphysical structure of immaterial entities other than God (angels, within the Christian tradition) in a way that would distinguish them from the absolute simplicity of God, especially for those who rejected the possibility of matter–form composition both for such entities and for human souls (see Chapters 21 and 46). Second, there was a need to account metaphysically for the distinction between God, the uncaused cause who necessarily exists, and all other beings, which depend on something else for their existence.

This famous scholastic dispute over the relationship between essence and existence has its roots in earlier Latin and Arabic discussions. Among Latin sources, Boethius was especially influential. He begins his De hebdomadibus by listing a series of axioms, some of which compare and contrast that-which-is (id quod est) and being (esse). Consider, for instance, Axiom II: “Being and that-which-is are diverse”; Axiom VII: “Every simple entity has its being and that-which-is as one”; and Axiom VIII: “In every composite entity its being and that-which-is are diverse.” With some exceptions, modern interpreters of Boethius do not see in this contrast a real distinction between essence and existence (esse) as two distinct intrinsic principles of being. Rather, according to many of these interpreters, Boethius compares and distinguishes between a concrete entity (that-which-is) and a form in which it shares (esse). In simple beings they are identical, whereas in composite beings they are diverse.

Thomas Aquinas was born in 1224/25 in his family's castle at Roccasecca, Italy. After receiving elementary schooling at the nearby Benedictine abbey of Monte Cassino, in 1239 he began to study liberal arts and philosophy at the newly founded studium generale at Naples. While a student there, he joined the Dominican Order in 1244, much to the chagrin of his family who wanted him to become a Benedictine. At the request of his mother, he was forcibly taken from the Dominicans by soldiers and detained at the family castle for a year or more; but all efforts on the part of his family to persuade him not to become a Dominican failed. In 1245 his family permitted him to rejoin the Dominicans, who promptly sent him to Paris for further studies. There he came into contact with Albert the Great, and after some years in Paris, journeyed to Cologne with Albert, under whom he studied from 1248 until 1252. From 1252 until 1256 he studied theology at the University of Paris and fulfilled the requirements for becoming a magister in theology, including lecturing on the Sentences of Peter Lombard, which resulted in his Commentary on the Sentences. At this time he also published his first two philosophical opuscula: De ente et essentia (On being and essence) and De principiis naturae (On the principles of nature).

For Aquinas metaphysics, first philosophy, and a philosophical science of the divine (scientia divina) are one and the same. Following Aristotle, he is convinced that there is a science that studies being as being. Like other theoretical sciences, metaphysics must have a given subject. According to Aquinas this subject is being in general [ens commune) or being as being. Aquinas describes this science in that way in order to distinguish it from the less extended and more restricted subjects of the other theoretical sciences - natural philosophy (which studies being as subject to change and motion) and mathematics (which studies being as quantified).

By emphasizing that the subject of metaphysics is being as being, Aquinas also establishes his position on an earlier controversy concerning the relationship between the science of being as being described by Aristotle in Metaphysics IV 1-2 and the “first philosophy” or “divine science” developed in Metaphysics VI 1. While the first approach emphasizes the nonparticularity of the subject matter of this science, the second seems rather to focus its study on one particular kind or range of being: separate and immaterial entity, or the divine. If Aristotle clearly attempted to identify these two as one and the same science at the end of Metaphysics VI1, not all interpreters believe that he succeeded.

First philosophy, divine science, and the science of ‘being as being’

The recovery of Aristotle's Metaphysics by medieval Western thinkers prepared the way for them to concentrate on the science of ‘being as being’ in the high Middle Ages. This work was enhanced by the translation into Latin of Avicenna's Metaphysics in the twelfth century and of Averroes' Commentary on Aristotle's Metaphysics in the early thirteenth century. But as medieval Latin thinkers began to examine Aristotle's text more closely, they encountered a problem of interpretation relating to the very nature of metaphysics.

In Metaphysics IV, c. 1 (1003a21–32), Aristotle speaks of a science which studies being as being and contrasts it with more particular sciences which restrict themselves to investigating the attributes of a portion of being. But in Metaphysics VI, c. 1 (1026a23–32), after referring to his investigation of ‘beings as beings’ and presumably, therefore, to his science of being as being, Aristotle distinguishes three theoretical sciences – physics, mathematics, and first philosophy or ‘divine science’ – and then seems to justify the viability of the last-mentioned one only insofar as it concerns itself with separate and immobile entities. One might wonder whether this first philosophy or divine science can be identified with Aristotle's general science of being as being, a difficulty which he himself recognises. He concludes the discussion by asserting that if there were no separate and immobile entity, then physics would be the first science.