ZABARELLA, JACOPO
(1532–1589)

Jacopo Zabarella was one of the leading Aristotelians of the sixteenth century. He taught at the University of Padua for twenty-five years, from 1564 until his death. The fruit of these years of lecturing is contained in his printed works, which include treatises on Aristotelian logic and natural science. His writings in logic, and especially on scientific method, earned Zabarella a reputation as the most outstanding logician of his time; they continued to be read by school philosophers in Germany and Italy for several generations after his death and still command respect as interpretations of Aristotle.

Zabarella proceeds in characteristic scholastic fashion, examining and resolving, independently of each other, a sequence of issues. In the process he canvasses the views of an impressive number of predecessors among the Latins and seems fully conversant with Greek philosophy, including the Greek commentators on Aristotle. The doctrines discussed by Zabarella range, as is usual with scholastic writers, over an immense amount of material, basically that presented by Aristotle in his Organon and in the Libri Naturales. As a philosopher Zabarella is willing to leave certain arguments to the theologians—for example, whether God could have created prime matter without form. "My advice is to dispute in Aristotelian, not theological, fashion," he remarks. This does not mean, however, that Zabarella was not willing to consider and even to endorse arguments of a strictly philosophical nature presented by theologians; hence, the names of Thomas Aquinas, John Duns Scotus, Gregory of Rimini, and many others frequently occur in his works, along with the appeals to Averroes so frequent among Italian philosophers of his time. Analysis of the arguments advanced by predecessors constitutes one part of Zabarella's presentation (ratio ); he also appeals to experience (experientia ), his own or that of most people. Thus, he mentions having climbed the highest hill in the vicinity of Padua, seeing clouds below, and learning when he descended in the evening that it had rained in the valley during the day. But there is no reference to controlled experiment in his writings; in this respect he remained a bookish philosopher, like most university professors of his time.

ZABARELLA, JACOPO
(1532–1589)

No one has followed Zabarella carefully through the maze of his discussions in order to secure a clear view of his total thought. The studies we have are partial and will doubtless require revision in the light of increased knowledge of the whole tradition he represents. Nevertheless, some of his conclusions can be definitely stated.

Zabarella regards Aristotle's science as perfect with respect to structure and form, imperfect only with regard to its subject matter. He compares Aristotle's writings on natural science with Euclid's Elements and suggests that the philosopher of nature can easily derive theorems of physics from the principles contained in them. Zabarella does not envisage the possibility that Aristotle's approach might be supplemented by mathematics. The fourteenth-century attempts at quantification in physics originating at Paris and Oxford had been transported to Italy by such teachers as Paul of Venice, but Zabarella does not seem aware of these developments. He did not welcome novel hypotheses, preferring, for example, to stand by Aristotle's explanation that the movement of projectiles can be attributed to pushing by the surrounding air (antiperistasis ). Zabarella rejects the view that the "preceding motion is the cause of the greater velocity of the following motion."

In his discussions of the heavens, Zabarella betrays no concern with the Copernican theory published during his youth. He seems slightly dubious about the epicycles of the astronomers, but in this he was no doubt simply reflecting the doubts of Averroes. Zabarella endorses the view, also derived from Averroes, that the "confused" knowledge of the world supplied by the natural scientist must be made "distinct" by the metaphysician. For example, he concedes that the argument, "Since there is eternal movement, there must be an eternal mover," may be established by the natural scientist, whose bailiwick is the consideration and causal explanation of things in motion. But consideration of immaterial substances in themselves (the "eternal motors") must be left to the metaphysician.

Contemporaries had raised a difficulty in connection with certain mutually canceling actions in nature ("reactions"), which seemed to them to defy the Aristotelian dictum "Nature never does anything in vain." Zabarella points out that such mutual frustration nevertheless does not frustrate nature in general, since all things turn out according to the law of universal nature (ex lege naturae universalis ).

Another question much discussed in scholastic physics concerned the elements in what we would call chemical compounds (called "mixtures" by the Schoolmen). Do they persist in existence after losing their sensible identity as elements and becoming part of the compound? Various solutions had been proposed to this problem; Zabarella accepts that of Averroes—the same "reality" of the elementary forms of matter is in the elements and in the mixture, but their "formality" is changed.

In Aristotelian metaphysics and philosophy the distinction between matter and form is crucial and difficult, especially in its application to human beings. School philosophers of Zabarella's time exercised a great deal of ingenuity in order to make sense of the Aristotelian doctrine that the soul is the form of the body. There were two main opinions: one, that the soul is a "form giving being" to man; the other, that the soul is merely a "form assisting" in man's operation, much as a sailor presides over the operation of an already formed ship. Zabarella chooses the former interpretation, although not without vacillation.

On another much disputed question, concerning the perception of sense qualities, Zabarella endorses the view of Albert the Great that there is no need to postulate an "active sense" (sensus agens ); certain sensed qualities have it in themselves to multiply their "spiritual" species in the medium, in contrast to such other qualities as heat, which really produce their counterparts in the medium and in the sense of touch.

Zabarella decisively rejects the Averroist thesis of the unity of the intellect, insisting that the intellect is multiplied according to the number of individual men. The intellect is the form of man; since it is not itself "in act," it is able to receive all things spiritually and hence is capable of knowing all things.

Logic

Zabarella's most original contributions lie in his logical works. The nature of logic and its relation to other disciplines were controversial matters even in antiquity, and these controversies were renewed during the Renaissance. Zabarella sides with the Greek commentators on Aristotle in maintaining that logic is not strictly a part of philosophy but an instrumental discipline furnishing other arts and sciences with tools of inquiry. Two of these tools are order and method. Order is an intellectual habit that teaches us how to dispose suitably the parts of any given discipline so that we can learn it more easily. Method is also an intellectual instrument producing knowledge of the unknown from that which is known, but it permits us to draw syllogistic inferences. The nature of both order and method must be clarified by an analysis of their objectives: ease of learning in the case of order, perfect knowledge (cognitio ) in the case of method.

These analyses are set forth in Zabarella's treatise De Methodis (On methods), in which he challenges two schools of thought prevalent in his time. One, drawn from Neoplatonic commentators on Aristotle, held that there are four methods employed in the arts and sciences: demonstrative, definitive, divisive, and resolutive. The other, advocated by medical men and drawn from Galen, held that there are three orders of teaching any discipline. Zabarella presents a simplified version, reducing the number of orders and methods to two. Contemplative disciplines are transmitted by the compositive order, practical or operative disciplines by the resolutive, which begins with the end to be achieved in any pursuit and reasons backward to an initial step in its direction.

This was traditional Aristotelian doctrine, but Zabarella's elaboration of compositive and resolutive methods was more original. In the natural sciences there are two things to be studied, substances and accidents. Substances can be investigated only by the resolutive method, which begins with sensible effects and "resolves" them into their causes. We know substances when we possess definitions of them, but these definitions, contrary to received opinion, are not "methods." Accidents, on the other hand, can be demonstrated by the demonstrative or compositive method once the principles discovered by the resolutive method are available.

In his work "On the Regress," Zabarella analyzes a special form of demonstration in which "the cause and the effect reciprocate, and the effect is more known to us than the cause." The best example of such a regress is to be found, Zabarella tells us, in Aristotle's Physics. We know in a confused way that where there is generation, there is matter, but only demonstration makes it clear to us why matter is the cause of generation. We must make use of a "mental examination," which tells us that matter is "that which is apt to receive all forms and privations."

Zabarella reaffirms man's central place in the universe; the operation of the most outstanding part of man is his highest perfection, and this is to be found in contemplation. Man is of a middle nature; he is the most noble animal, created in the image of God, but there is also a sense in which he is ignoble and imperfect, the sense in which we say, "To sin is human" or "After all, he is only a man." Such concern for placing man in nature probably echoes fifteenth-century humanism.

Bibliography

None of Zabarella's works has been translated into English, and this is unfortunate, since he ranks high as an expositor of Aristotle. Furthermore, copies of his Opera Logica (published first in Venice, 1578, but many times thereafter) are hard to obtain. The same may be said of his De Rebus Naturalibus (Venice, 1590) and his commentaries on the Physics and De Anima. A modern edition of the De Methodis and other logical works would be welcome and would furnish us with one of the most sophisticated expositions of school logic and thinking concerning scientific method to be given during the Renaissance.

For studies on Zabarella, see Ernst Cassirer, Das Erkenntnis problem in der Philosophie und Wissenschaft der neueren Zeit (Berlin: Cassirer, 1906), Vol. I, pp. 134–141; John Herman Randall Jr., The School of Padua and the Emergence of Modern Science (Padua, 1961), pp. 49–63 (gives ample quotations in Latin); N. W. Gilbert, Renaissance Concepts of Method (New York: Columbia University Press, 1960), Ch. 7; J. J. Glanville, "Zabarella and Poinsot on the Object and Nature of Logic," in Readings in Logic, edited by R. Houde (Dubuque, IA: Brown, 1958); Riccardo Pozzo, ed., The Impact of Aristotelianism on Modern Philosophy (Studies in Philosophy and the History of Philosophy, Vol. 39) (Washington DC: Catholic University of America Press, 2004); and William A. Wallace, "Circularity and the Paduan 'Regressus': From Pietro D'abano to Galileo Galilei." Vivarium 33(1)(1995): 76–97.