The Thomist 65 (2001): 441-63

SCIENCE AND RELIGION IN THE THOMISTIC TRADITION⁽¹⁾

William A. Wallace, O.P.

University of Maryland

College Park, Maryland

The topic "Science and Religion" continues to be much discussed in the present day, particularly in the context of an opposition or warfare between the two.⁽²⁾ It is a commonplace that in the past those interested in such discussions have inclined more to the side of science than they have to the side of religion. On the religion side, it seems that Catholics rarely get excited about the subject, whereas for Protestants it is a topic of ongoing, and in some cases intense, interest. Indeed, among historians of science it is not unusual to find persons who turned away from a career in science, to which they had first aspired, to study history--to set the record straight, as it were, on the relationship between science and religion.

The fruits of labors of this type are now apparent in a volume that has just appeared bearing the title The History of Science and Religion in the Western Tradition: An Encyclopedia.⁽³⁾ It may seem odd that a topic such as this should have a history, but if it has been around for a century or so it seems inevitable that it would

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take on a life of its own and so become deserving of historical treatment.

It is not our intention here to review this multifaceted work. Suffice it to note that there are some serious omissions in the essays, over a hundred in number, that make up the volume. With regard to the two main terms, there is no clear-cut definition of what constitutes a religion and how one religion is differentiated from another, nor is there any serious treatment of the term "sci-ence" and the various meanings it has taken on from Aristotle to the present day.⁽⁴⁾ Perhaps more serious, there is no essay on faith, and there are only seven references to that term in the almost six hundred pages that make up the volume. Again, there is no essay on theology, nor is the term even mentioned in the index.⁽⁵⁾

Among Catholics, as suggested above, the general attitude toward this topic seems to be lack of interest.⁽⁶⁾ This is especially true of those who identify in some way or other with the Thomistic tradition. If they are knowledgeable about the origins of Thomism in the works of Albert the Great and those of Thomas Aquinas, they see a complementary relationship between science and what now passes under the name of religion. At the same time they are aware that there are important differences between scientia and fides.⁽⁷⁾ Among contemporary philosophers

of science, of course, there are those who think of science in terms of belief, as when they refer to science as "justified true belief." But then one has to consider what they mean by the qualifiers "justified" and "true"--and when that is done, it is evident that there is no connection whatever between their usage of the term "belief" and its meaning in a theological context.⁽⁸⁾

In light of this situation, our essay begins with St. Thomas's thought on the differences between scientia and religio, and then discusses the development of Thomism in a general way as it relates to the history and philosophy of science. After that it goes into fuller detail on two themes directly related to the Thomistic tradition, namely, the efforts of Galileo and others to demonstrate the motion of the earth, and the prospects for a renewed interest in Thomism as a philosophy of science in the present day.

A) Science and Religion

The juxtaposition of science and religion in the modern mind, with the connotation that the two must be either opposed or linked in some way, does not resonate significantly with Aquinas's thought. Much of what is now discussed under the category of science and religion he would have seen as part of a larger problem of the relationship between faith and reason. Once the respective spheres of these two types of knowing are made clear, most of the difficulties arising in debates over science and religion may be seen to disappear.

In brief, faith is taken by Thomas to mean belief in God and acceptance of divine revelation as true.⁽⁹⁾ He would differentiate it from reason on the basis of the fact that reason refers to the way

humans acquire knowledge through their natural powers of sense and intellect alone, without relying on God or supernatural revelation. His distinction focuses more on the mode of ac-quisition of knowledge than on the knowledge acquired. A person whose reason is complemented by faith would, for him, be capable of knowing more truths than one who knows through reason unaided. But if contradictory truths seem to derive from the two sources, then the competing claims of faith and reason have to be resolved, and we are faced with what even he would recognize as a "science vs. religion" controversy.

To be more precise, faith for Aquinas is a supernatural virtue (along with charity and hope) that accompanies grace in the souls of Christians and disposes them to believe in truths revealed by God. Such truths are not self-evident to human reason, and assent to them must be determined by a voluntary choice. If such a choice is made tentatively it is called opinion; if it is made with certainty and without doubt it is called faith. The objects of divine faith are formulated in creeds that are made up of articles, that is, of connected parts. Believing in such articles means putting faith in them, and this resembles knowing in its giving firm assent; it also resembles doubting or holding an opinion in that it does not entail a complete vision of the truth. Faith's assent is an act of the mind that is voluntary--it is determined not by reason but by the will. But since its object is truth, which is the proper object of the intellect, it is more proximately an act of the intellect and so is regarded as an intellectual virtue.⁽¹⁰⁾

Religion, like faith, is a virtue for Aquinas, but it resides not in the intellect but in the will.⁽¹¹⁾ It is allied to the virtue of justice, which disposes a person to render to others their due. Since humans owe their entire being to God they owe him a special kind of honor. Obviously they can never repay him for what he has given them, nor can they give him as much honor as they ought, but only as much as is possible for them and is deemed acceptable to him. Those who are sensitive to this obligation are in fact religious persons. Being religious in this sense does not

involve having any special scientific knowledge and thus does not bear directly on "science vs. religion" controversies.⁽¹²⁾

Science or scientia is also a virtue for Aquinas, but it is a natural virtue of the human intellect.⁽¹³⁾ It was characterized by Aristotle as a type of perfect knowing wherein one understands an object in terms of the causes that make it be what it is. It is attained by the type of reasoning called demonstration that meets the norms of Aristotle's Posterior Analytics and as such is certain and not revisable.⁽¹⁴⁾ In no way dependent on divine faith, it falls completely outside the sphere of religious assent. Most of what passes under the name of "science" in the present day, of course, is fallible and revisable, and as such would be classified as opinion and not as science in the strict sense. This raises the question whether there is anything in modern science that is certain and unrevisable, a question to be addressed in the last part of this essay.

B) Thomism and the History of Science

With the element of religiosity removed, Thomism--as exemplified in the works of both Aquinas and his followers--can be characterized as an intellectual movement within medieval Aristotelianism. As such its major characteristics may be seen by contrasting it with four other varieties of Aristotelianism that flourished in the medieval period, namely, Augustinian, Averroist,

Scotist, and nominalist.⁽¹⁵⁾ Augustinian Aristotelianism generally rejected any attempts to separate reason from faith and ap-proached the study of nature in an ambience dominated by faith. Averroist Aristotelianism placed the greatest trust in reason and saw all of truth as contained in the writings of Aristotle, thus leaving no room for faith. Steering a middle path between the two, St. Thomas granted autonomy to reason in the study of nature but allowed for reason to be complemented by faith in the realm of supernature. Indeed, so great was his commitment to reason that some of his teachings fell under ecclesiastical condemnation in 1277 at both Paris and Oxford. The remaining two varieties of Aristotelianism developed in reaction to the condemnations. That of John Duns Scotus questioned the primacy Aquinas accorded to the intellect and placed emphasis instead on the will. His synthesis can be seen as articulating a position between Augustinianism and Thomism, though closer to the former. Nominalist Aristotelianism, as seen in the works of William of Ockham, reacted against the Scotistic version and further attenuated its knowledge claims by making singulars the object of the intellect and reducing demonstration to the level of hypothetical reasoning. The medieval mendicant orders institu-tionalized these teachings, with the Dominicans being the main but not exclusive proponents of Thomism and the Franciscans proponents of Scotism and Ockhamism.

Though not a scientist in the modern sense, Aquinas addressed many problems that arose in the medieval Aristotelian, Archi-medean, Ptolemaic, and Galenic counterparts of modern physics, astronomy, chemistry, and the life sciences.⁽¹⁶⁾ In the study of

motion, for example, he held that velocity is a mode of continuous quantity and thus is capable of intensification in the same manner as qualities. He further taught that if, by an impossibility, a vacuum were to exist, motion through it would still take time, since its temporal character does not arise uniquely from external resistance. Both of these teachings influenced fourteenth-century thinkers in their quantitative analyses and speculation about internal resistances to motion, thereby fore-shadowing the modern concept of inertia. He regarded gravi-tation as the natural motion of a heavy object to its natural place but denied that it was caused by an absolute principle such as a vis insita. In this he implicitly rejected the absolute space and attractive forces later proposed by the Newtonians, and opted for relational concepts that have more affinity with those of modern relativity. He took up the problems of the magnet, of tidal variations, and of other occult phenomena, and was intent on reducing them to natural, as opposed to supramundane, causes. His analysis of magnetism was known to William Gilbert and was praised by him. In astronomy he was cognizant of the major mathematical theories of the universe and of Ptolemy's use of eccentrics and epicycles, but he was aware that all are based on hypothetical reasoning. He is often cited for voicing his expec-tation that Ptolemy's theory would one day be superseded by a simpler explanation. On the structure of matter he introduced a distinctive teaching on how elements are present in compounds, holding that they are not present there actually or potentially, but only virtually. His concept of virtual presence dominated all subsequent medieval teachings on the subject and still has relevance in the present day. In the life sciences he wrote a treatise on the heart in an attempt to trace lines of causality in its motion. And, like his contemporaries, he believed in spontaneous generation and countenanced a qualified type of evolution in the initial formation of creatures.

Most of the contributions of his followers, the Thomists, to the history of science consist in defenses and developments of

Thomas's thought on these particular points. They are contained in commentaries on his writings, on the Sentences of Peter Lombard, and on the works of Aristotle. In England the foremost Thomists were William of Hothum, Richard Knapwell, and Thomas Sutton. In France the principal Thomists were Hervaeus Natalis and John Capreolus. Among early Germans one might name John of Sterngasse, Nicholas of Strassburg, and Theodoric of Freiberg; later we might mention John Versor. In Italy the early group included Rambert of Bologna and John of Naples. Fifteenth-century expositors included Dominic of Flanders and Tommaso de Vio Cajetan, the latter important for his disputes with Averroists at the University of Padua over the immortality of the human soul.⁽¹⁷⁾

Much work yet needs to be done to assess the full impact of Thomism on the development of science from the thirteenth through the fifteenth century. By far the most important Domini-can for medieval science was Theodoric of Freiberg, whose experimental work in optics is universally acknowledged as its crowning achievement. Theodoric came from Albert the Great's province (of Teutonia) and studied at the University of Paris right after Aquinas's death.⁽¹⁸⁾ He used Thomas's commentaries on the Posterior Analytics and his exposition of the rainbow as a plan for his research. To these he added an important insight from St. Albert the Great, namely, that individual raindrops are what cause the rainbow, not clouds, as was otherwise thought in his day. Theodoric's genius is seen in his extensive experimental work, working with crystals and spherical flasks of water to trace the passage of light rays through them, to see how they produced

the colors of both the primary and the secondary rainbow. This led him to the first essentially correct explanation of that phe-nomenon, for which credit is usually given to Descartes, though Theodoric anticipated Descartes's work by over three hundred years.⁽¹⁹⁾

Cajetan was largely responsible for a revival of Thomism, sometimes called "Second Thomism," which played a significant role in early modern science (i.e., that of the sixteenth and seventeenth centuries). Here the locus of activity shifted to the Iberian peninsula, where the principal Dominicans were Francisco Vittoria, Domingo de Soto, Melchior Cano, and Domingo Bañez. Of this group Soto is of particular significance for his questions on the Physics of Aristotle, in which he adumbrated the concept of uniform acceleration in free fall.⁽²⁰⁾ Soto is even more important for the history of science than was Theodoric of Freiberg, for there is indirect evidence that Soto's work may have influenced Galileo Galilei in his famous discovery of the laws of falling bodies. Such evidence is discussed elsewhere, but the following brief account may suffice for purposes of this essay.⁽²¹⁾

The Jesuit Order newly founded by Ignatius Loyola contributed substantially to the development after Soto, since Loyola's constitution enjoined Thomism on them in their teach-ing of theology, while allowing them to be eclectic Aristotelians in their work in philosophy. Early professors at the Collegio

Romano, the principal Jesuit institution of learning founded by Loyola himself, relied heavily on Thomistic authors, but as the order grew it developed its own distinctive teachings. These are seen mainly in the writings of Francisco Suarez and Luis de Molina, who also incorporated Scotistic and nominalist strains in their thought.

One of Soto's students at the University of Salamanca who was already a priest, Francisco Toledo, joined the Jesuit Order and was sent almost immediately to the Collegio Romano to serve there as a professor of philosophy.⁽²²⁾ By the end of the sixteenth century the courses he inaugurated in logic and natural philosophy had become highly developed. Some time ago it was discovered that Galileo Galilei obtained lecture notes from this period at the Collegio that are Thomistic in orientation, most notably those of Paulus Vallius.⁽²³⁾ Between 1589 and 1591 Galileo appropriated materials from Vallius's lectures that are still extant in his Latin notebooks, composed when he had just begun teaching at the University of Pisa. The influence of the notebooks dealing with physical questions and with motion on Galileo's later work is gradually being recognized among scholars.⁽²⁴⁾ More important, it is now generally accepted that his notebook dealing with logical questions, essentially an exposition of the teaching on demonstration in the Posterior Analytics, guided his scientific investigations throughout his life.⁽²⁵⁾

Both Jesuits and Dominicans played an important part in Galileo's trial in 1633. Despite their differences both groups subscribed to a Thomistic theory of knowledge and of demon-strative proof. In their eyes it was Galileo's inability to provide a demonstration of the earth's motion that brought about his downfall.⁽²⁶⁾ Recently records have been discovered showing that the Dominican Benedetto Olivieri recognized by 1820 that empirical proofs of the earth's motion--stellar parallax and the deflection of falling bodies towards the east--had by then been given. By invoking such proofs Olivieri was instrumental in having the Church finally remove its long-standing sanctions against Copernicanism and Galileo.⁽²⁷⁾

Apart from its role in the early modern period, Thomism entered a third phase of development during the late nineteenth and twentieth centuries in a movement known as the Thomistic Revival or Neo-Thomism. Impetus for this revival came from Pope Leo XIII, whose encyclical Aeterni Patris of 1879 called for a return to the thought of St. Thomas as a means of solving con-temporary problems. This papal endorsement stimulated much historical research, including that bearing on the history of science. In the early twentieth century the Catholic Pierre Duhem, though not a Thomist himself, used history to develop a positivist philosophy of science that restricted science's epistemic claims. He did so in order to protect the Church's metaphysics against encroachments from the science of his day, which was very anti-

clerical and materialist in its orientation. Apart from Duhem, twentieth-century Catholics have shown little interest in science, being concerned mainly with metaphysics and social and political thought. Notable exceptions are Jacques Maritain, Charles de Koninck, and Vincent Edward Smith, all of whom developed philosophies of science.⁽²⁸⁾ All three, in my view, were too much influenced by Duhem and the Critique of Science Movement, and tended to deny to modern science the possibility of attaining demonstrations in the world of nature. A moderate realist position that allows such a possibility seems more in accord with Aquinas's own thought.

C) Galileo and Proof of the Earth's Motion

Before exploring this possibility, let us return to the problem of demonstration of the earth's motion and how it was finally effected in the early nineteenth century. This will require us to back-track for a moment to see how Galileo attempted to prove that the earth moves and the difficulties he encountered. From this we can then sketch other attempts at a proof that ultimately proved to be successful.⁽²⁹⁾

Galileo's notion of demonstration, which he appropriated from the Jesuits, was actually that of Jacopo Zabarella and the Paduan Aristotelians.⁽³⁰⁾ It involved what is called the demon-strative regress: a procedure wherein one reasons from effect to

cause in a provisional way, and then, after testing and verifying the supposed connection between cause and effect, goes backward (or regresses) to the cause again and sees it as offering the unique and proper explanation of the effect. The technique is most easily applied in the "mixed sciences" first developed by Archimedes, namely, those that use a mix of mathematical and physical premises, for in these one can most readily employ simplifying suppositions, indirect proofs, and rigorous methods of approximation.

Throughout most of his early period Galileo subscribed to and taught the Ptolemaic (or earth-centered) system of the universe, although he knew of, and occasionally flirted with, the Coper-nican (or sun-centered) system.⁽³¹⁾ His astronomy was contained mainly in his Treatise on the Sphere, written around 1606. This was not a planetary astronomy but one that concerned mainly the motions of the earth, moon, and sun. The problems he addressed involved only relative motion and the demonstrations he offered would be valid in either system. The heavens were not his main interest at this time. His enduring preoccupation was the study of mechanics and motion. He made marvelous progress in both, initially with his provisional insights at Pisa, then with a dogged experimental program at Padua that enabled him to formulate and verify the basic laws of motion. At both universities he employed the demonstrative regress with good effect to move both studies to the level of Aristotelian sciences. But that result paled before his improvement of the telescope as an astronomical instrument and the marvelous discoveries he made with it in late 1609 and 1610. The same regress, now combining refined sense observations with irrefutable projective geometry, yielded "neces-sary demonstrations" that would electrify Europe and set astronomy on an unsuspected new course.

The dividing line between Galileo's first and second periods, paradoxically, was drawn by these demonstrations. To under-stand this one must appreciate that Galileo's view of science was

very different from our own. Recent science is identified with theory, with series of conjectures and refutations, one succeeding another without end, with no result final and irrevisable. Galileo's knowledge claims were not of this type. He knew that he had offered more than conjectures, that he had really demonstrated the existence of mountains on the moon, satellites of Jupiter, Venus's orbiting of the sun.⁽³²⁾ With these results, the Ptolemaic system could no longer be entertained, even as a possibility. He jettisoned it without further ado and became an ardent supporter of Copernicus.

Galileo's second period, inaugurated by his move to Florence as "mathematician and philosopher to the Grand Duke of Tuscany," saw him dropping all work on motion and mechanics to inaugurate a new crusade. Its aim was unambiguous: to convince the Catholic Church that it is the earth that moves, not the sun, despite statements in the Scriptures to the contrary. The period was one that saw few new discoveries, was filled with polemics and controversy, and came to a tragic end. Only after it was over, in the relative tranquillity of his house arrest at Arcetri during his third and final period, could Galileo turn back to the scientific work of his youth and publish the Two New Sciences, for which he is justly proclaimed the "Father of Modern Science."

Predictably, Galileo's difficulties with the Church dominated the second period. Shortly after he began urging the reality of Copernican teaching on the earth's motion and the sun's rest he was denounced to Rome as rejecting the traditional interpretation of the Scriptures on that subject. The situation was exacerbated when a Carmelite theologian in Naples, Paolo Antonio Foscarini, came to Galileo's defense and argued that the Bible could be interpreted in a way that sustained the Copernican teaching. This gave rise to the document we might say started the whole "Galileo Affair": a letter of 12 April 1615 from Cardinal Robert Bellarmine to Foscarini, explicitly directed to Galileo also, warning both that they stood on dangerous ground.⁽³³⁾ Bellarmine

commended them for their prudence in speaking "supposi-tionally," that is, for holding, on the supposition that the sun stands still and the earth moves, that one can save the appear-ances of the heavenly motions. But that is very different from offering a "true demonstration" that the sun is at the center of the world and the earth is in orbit around it. If there were such a demonstration, Bellarmine admitted, the situation would be quite different. But to his knowledge no demonstration of this type existed, and he had grave doubts about whether it ever could.

Much research has been done recently on Bellarmine, Foscarini, and another defender of Galileo, the Dominican Tommaso Campanella, in the context of this letter.⁽³⁴⁾ While quoting the Council of Trent on the interpretation of Scripture, it seems that Bellarmine went considerably beyond the council in explaining how the motion of the sun and the earth's immobility were a matter of faith. For him, this was not because of the subject matter being treated but because of the one informing us about it, namely, the Holy Spirit. This seems to have been behind Bellarmine's personal conviction that the earth's motion could never be demonstrated, even though he was willing to entertain the possibility of a demonstration. On his reading of Trent, everything in the Bible became a matter of faith simply because it was the word of the Holy Spirit.

Alarmed by this and other signs that the Church might condemn Copernicanism, Galileo traveled to Rome late in 1615 to head off such action. We can safely presume that his own views on demonstration, deriving as they did from Jesuit teaching notes, were in general agreement with Bellarmine's, who was a Jesuit and had himself taught at the Collegio Romano. But it should be noted here that there can be ambiguity when applying the expression "suppositionally" (Lat. ex suppositione) to demon-strations in the mixed sciences. These invariably are based on suppositions--not mere hypotheses, as Bellarmine understood the expression, but the kind that can be verified in physical situations, à la Archimedes. No doubt Galileo understood what Bellarmine

meant, but he himself, thinking of the Archimedean usage, resumed work on what he hoped would meet the demand for a "true demonstration" of the earth's motion, the famous argument from the tides.⁽³⁵⁾

The basic idea for the argument had occurred to him many years earlier. As he saw it, a twofold motion of the earth, one of annual revolution around the sun, the other of diurnal rotation on its axis, is probably the primary physical cause of the back-and-forth motion of the seas on the earth's surface. To this he proposed to add secondary or concomitant causes to account for the diversity of tidal movements. In a letter to Cardinal Alessandro Orsini dated 8 January 1616 in which he explained this, Galileo concluded on the note that he thus would harmonize the earth's motion and the tides, "taking the former as the cause of the latter, and the latter as a sign of and an argument for the former"--a quite concise description of the demonstrative regress.

Seven years later, in 1623, a Florentine cardinal who had befriended Galileo, Maffeo Barberini, was elected to the papacy as Pope Urban VIII. The next year, in an audience with the new pope, Galileo explained his demonstration of the earth's motion from the ebb and flow of the tides and expressed his interest in resuming work on the Copernican system, despite the warning he had received in 1615 from Bellarmine. Urban was not impressed with the tidal argument and discouraged Galileo from using it, but apparently he gave permission for Galileo to do a comparative study of the two chief world systems, the Ptolemaic and the Copernican. Galileo returned to Florence, and by 1630 had completed a draft of the new work on this subject, which he entitled simply the Dialogue. He submitted it for approval to the censor, a Dominican named Niccolò Riccardi, then Master of the Sacred Palace.

Riccardi was favorable to Galileo but he was uneasy with the manuscript, for it made use of the argument from the tides, of which he knew the pope did not approve, and it clearly presented the Copernican system as superior to the Ptolemaic. Riccardi nonetheless made suggestions for changes at the beginning and at the end, and, when Galileo had made them, approved it for publication. The Dialogue was printed at Florence early in 1632. It was greeted with enthusiasm by Galileo's friends, but in Rome it provoked a decidedly unfavorable reaction. By summertime the pope was so distressed that he ordered the printer to hold up its distribution and appointed a special commission to bring Galileo to trial for publishing it as he had.

Thus came about the famous trial of Galileo in 1633. There are many things one might say about the trial and its aftermath. Here we will address only one small question. Had Galileo actually proved that the earth moves, did he feel he had succeeded in demonstrating the earth's motion, thus holding it as true and certain? If so, he would have lied under oath and perjured himself when he claimed during the trial that he did not hold for the earth's motion. Many people think that he did just that: this was Berthold Brecht's judgment on him, and it is that of recent biographer James Reston in his book Galileo: A Life. But that is hard to believe. The argument from the tides was a very fragile argument and Galileo had been patching it up for years, with little success. The earth's motion, on the other hand, is notoriously hard to prove. A better reading of what happened is that a plea-bargaining tactic with Galileo worked out by the prosecutor (the Dominican Maculano Firenzuola) at the end of the trial worked, and probably in a way he had not dreamt it might. He effectively called Galileo's bluff on the tidal argument, and latter's bravado simply caved in. Galileo knew in his heart that he had not demonstrated the earth's motion; he was too good at logic for that. Once he admitted this to himself, the work of the prosecution was over. For, if Galileo still had doubts, as well he might, about the argument from the tides, the basis for the trial had changed. That left room for his acceding to the Church's teaching (wrong though we now know it was) until such time as

conclusive proof became available. And although other evidences began to appear in the eighteenth century, it is generally agreed that the earth's motion was not completely accepted until Friedrich Bessel's measurement of stellar parallax in 1838 and Léon Foucault's experiments with the pendulum in 1851--both of which were still a long way off in 1633.

Oddly enough, the recent researches of Pope John Paul II's Galileo Commission have disclosed that the Church actually removed its prohibition against Copernican teaching in 1820, and this on the basis of demonstrations of the earth's motion earlier than Bessel's and Foucault's.⁽³⁶⁾ The occasion arose in 1820 when Giuseppe Settele, astronomy professor at the Sapienza (now the University of Rome), requested permission to print the second volume of his Astronomia, which taught, on the basis of new evidence, that the earth moves. Permission was denied by the Master of the Sacred Palace, the Dominican Filippo Anfossi, on the basis of the Church's 1616 decree against Copernicanism. Earlier, Settele had asked his colleague at the Sapienza, yet another Dominican, Benedetto Olivieri--who was professor of Old Testament there but also happened to be Commissary of the Holy Office--whether he could openly teach the earth's motion without running into difficulty with the Church. Olivieri, aware of changing interpretations of Scripture and new scientific evidence, had replied in the affirmative. A controversy thereupon ensued between the two Dominicans, Anfossi and Olivieri, both Thomists--the first of a conservative mold, the second clearly a progressive. The latter, being the more knowledgeable of the two, was able to convince Pope Pius VII and the cardinals of the Holy Office of the correctness of his views. Anfossi was silenced, the imprimatur sought after was granted late in 1820, and the second volume of Settele's Astronomia came off the press on 10 January 1821.

The new scientific proofs advanced by Olivieri in presenting his case to the pope are found in the works of two little-known Italian astronomers, Giovanni Battista Guglielmini and Giuseppe

Calandrelli. The first was professor of mathematics at the University of Bologna and the second director of the observatory in Rome at the Collegio Romano. Olivieri pointed out that, in experiments performed at Bologna between 1789 and 1792, Guglielmini offered the first physical proof of the earth's rotation. Similarly, Calandrelli had measured the parallax of star Alpha in constellation Lyra and so presented what Olivieri called "a sensible demonstration" (una dimostrazione sensibile) of the earth's annual motion. This he had done in a work published in 1806, which he had in fact dedicated to Pope Pius VII.

For our purposes here Guglielmini's demonstration is the more interesting, since it involved the Torre dei Asinelli in Bologna, the same tower the Jesuit Giambattista Riccioli had used in 1640 to verify experimentally Galileo's law of falling bodies. Guglielmini took inspiration from a passage in Galileo's Dialogue where, on the Second Day, he is discussing the fall of an object from the orb of the moon to the earth's surface. Rather than falling to a point directly beneath the point from which it is released, the object should "run ahead of the whirling of the earth" and land at a point farther to the east. This should come about because, at the time of its release, the object would have a greater horizontal component in its motion the more distant it would be from the earth. The effect would not be noticed with objects dropped from a ship's mast or from a low tower, but it might be noticeable with those dropped from a high tower such as the Torre dei Asinelli. Sir Isaac Newton was aware of this possible test, and so was Pierre Simon de Laplace, who suggested it to Joseph Jerome Lalande, director of the Paris observatory, who unfortunately never performed it. Thus it was left for Guglielmini to do so. He made a number of tests from the Torre at a height of 78.3 meters and measured, on an average, a deviation of 19 mm. to the east. Concerned about atmospheric disturbances at the Torre, he also measured drops from a height of 29 meters in a spiral staircase inside the astronomical observatory at Bologna and found a deviation there of 4 mm. to the east.

Guglielmini was in communication with a German astrono-mer, Johann Friedrich Benzenburg, who dropped objects from the

campanile of a church in Hamburg in 1802, at a height of 76.3 meters, and again from within a mine shaft at Schelbusch in 1804, at a depth of 85.1 meters, and obtained comparable results. Rough confirmation was also obtained by Ferdinand Reich, who performed tests in a mine shaft at Freiberg in Saxony, at a depth of 158.5 meters, in 1831. It turned out that longer falls were not necessarily more accurate indicators, because perturbing factors, both in the open air and within mine shafts, introduced effects much greater than that being measured. Definitive tests were finally made in the United States by Edwin Herbert Hall in 1902, working at Harvard under very controlled conditions, at a latitude close to that of Bologna. With a drop of 23 meters, Hall measured a deviation of 1.50 ± 0.05 mm. to the east, against a predicted value of 1.8 mm.

When one considers the problems encountered in demon-strations such as Guglielmini's, and the length of time it took to solve them, one can appreciate the enormous difficulty faced by Galileo with his argument from the tides. Actually his insights were correct: there are mathematical effects in the tides' motions that might be produced by the earth's motion, but these are so minute as to be undetectable by physical measurements. It also turns out that there was nothing wrong with his logic--the demonstrative regress was the proper technique to use in seeking a proof of this type. Galileo simply underestimated the difficulty of his undertaking. For this he surely deserves the greatest sym-pathy. Perhaps the theologians of 1633 deserve some sympathy also, unless we are to condemn them, as some wish to do, for not being prescient enough to see hundreds of years into science's future.

The point of all this is simply that the norms pointed out at the beginning of this essay, stated explicitly to Galileo by Cardinal Bellarmine, and already agreed to by Galileo in his Letter to the Grand Duchess Christina, were still in effect in 1820. As soon as a demonstration of the earth's motion had been achieved, it had become a fact known by reason and its contrary could no longer be held "on faith." The opposition between science and religion ceased at that point, and the Church finally recognized this. It

had taken almost two hundred years to establish the fact, and indeed its factual status had still to be reinforced by the more precise discoveries of Bessel and Foucault. But the distinction was valid, and the Church can hardly be condemned for adhering to it as long as it did--although one may well wish that the discoveries had been made a lot sooner.

D) Thomism as a Philosophy of Science

The demonstration of the earth's motion by empirical science was not expected by many, and yet such a demonstration, when it came, did cause the Church to rethink its position on Coper-nicanism and ultimately to close the case on Galileo. There is no doubt, then, that demonstration is an important concept for resolving potential conflicts between science and religion.⁽³⁷⁾ It is even more important for resolving serious problems that have arisen within the last decade or two within the philosophy of science. This thesis has been argued in my book The Modeling of Nature: Philosophy of Science and Philosophy of Nature in Synthesis.⁽³⁸⁾ The following is a brief summary of the theme of that work and its relevance to the topic of science and religion.

Our scientific knowledge of the universe surpasses that of any previous age. Yet, paradoxically, the philosophy of science movement is now in disarray. The collapse of logical empiricism and the rise of historicism and social constructivism have effectively left all of the sciences without an epistemology. The claims of realism have become increasingly difficult to justify, and, for many, the only alternatives are probabilism, pragmatism, and relativism.

But the case is not hopeless. Human beings have a natural ability to understand the world in which they live. Many have suggested that this understanding requires advanced logic and mathematics. To the contrary, nature can more easily be under-stood through the use of simple modeling techniques. That explains the title of the book, The Modeling of Nature. In its first part, through the use of iconic and epistemic models a quasi-intuitive knowledge of the philosophy of nature is built up.⁽³⁹⁾ Selected materials from cognitive science are there employed to provide a model of the human mind that illuminates not only the philosophy of nature but also the logic, psychology, and episte-mology that are requisite to it.

The second part of the book is devoted to renovating the philosophy of science. The purpose of this part is twofold: to provide an epistemic justification of the insights provided in the first part and, in the process, to delve into aspects of logic and epistemology that are treated more by philosophers of science than by natural philosophers. It begins with an overview of the philosophy of science movement as this developed in the twentieth century, mainly in an Anglo-American setting, pointing out how it relates only tangentially to the study of nature. Following this an analysis is given of probable reasoning as it has become canonical for philosophers of science in the United States, showing its similarities with dialectical or topical reasoning in the Aristotelian tradition. The main contribution comes in the chapter entitled "The Epistemic Dimension of Science," where the case is presented for going beyond probable reasoning to restore the notion of epistm to science, and, through its use, to seeing some science, at least, as providing true and certain knowledge. By way of application, eight conceptual histories are then considered, ranging from medieval to recent science, and detailing how demonstrations were actually arrived at in different fields of science. The concluding chapter takes up various controversial aspects of these demonstrations and explains how disputes were

finally resolved, thus supporting the epistemic thesis advanced in the previous two chapters. Implicit in this discussion is a philosophy of science that is based on knowledge of nature rather than on formal logic and that harvests the fruit of science's history as this serves to clarify its philosophy. Thus it is able to bypass the technicalities that burden the literature of the philosophy of science movement and so bring the discipline closer to the commonsense realism by which scientists actually live and operate.

One can see from this how important the concept of demonstration is for advancing the cause of realism in modern science. Neither Maritain nor de Koninck nor Smith ever faced up to this problem and they were content to leave all of modern science, as did Pierre Duhem, within the domain of probable knowledge. Demonstration, of course, is not easy to teach. Yet the task is manageable. And demonstration is important, not simply for the philosophy of science, but also for saving the philosophy of nature as a discipline. It should also be understood and preserved as one of our most valuable tools for heading off science-religion conflicts in the future.

1. This essay is based on a lecture given at St. John's University, Jamaica, New York, on 16 October 1996, as part of a series on Science and Religion.

2. The best-known exposition of the warfare thesis is that of Andrew Dickson White, A History of the Warfare of Science with Theology, 2 vols. (New York: Appleton, 1897). This was preceded by the also well-known work of John William Draper, History of the Conflict Between Religion and Science (London: 1874; reprint, New York: Appleton, 1928).

3. Gary B. Ferngren, ed., The History of Science and Religion in the Western Tradition: An Encyclopedia (New York and London: Garland Publishing, Inc., 2000).

4. There is an essay entitled "The Demarcation of Science and Religion" (ibid., 17-23), but this is essentially a reworking of arguments for and against a demarcation between science and metaphysics, or between science and non-science, which for positivists degenerated into their distinction between science and nonsense.

5. There is, however, an entry for a book entitled The Theology of Electricity, by Ernst Benz (trans. Wolfgang Taraba [Allison Park., Penn.: Pickwick, 1989]), which explores seventeenth and eighteenth century debates on electricity. This is not the sense of theology that is here intended.

6. Perhaps this serves to explain why there is a minimal Catholic presence in the volume. Only two Catholic priests are among the contributors, Stanley L. Jaki, who wrote an essay on "God, Nature, and Science" (Science and Religion in the Western Tradition, 45-52), and William A. Wallace, O.P., who wrote on "Thomas Aquinas and Thomism" (ibid., 137-49). Among Catholic laymen the most notable from Catholic institutions are Richard J. Blackwell, who authored the article on "Galileo Galilei" (ibid., 85-89), and Michael J. Crowe, who wrote on "The Plurality of Worlds and Extraterrestrial Life" (ibid., 342-43).

7. This theme has gained importance for Catholics from the promulgation of Pope John Paul II's encyclical Fides et Ratio in September 1998. On that encyclical in the present context, see William A. Wallace, O.P., "Fides et Ratio: The Compatibility of Science and Religion," forthcoming in the Proceedings of the National Catholic Bioethics Center's Eighteenth Workshop for Bishops, Dallas, Texas, 5 February 2001.

8. "Justification" is usually understood by such philosophers in terms of hypothetico-deductive methodology, which may be capable of arriving at some degree of probability but is incapable of attaining certitude. Then truth is taken for the "truth value" of a formal deductive system, or in terms of a coherence theory of truth, as opposed to a correspondence theory--in the sense of an adaequatio rei et intellectus, which is required for knowing epistemically or in a strictly scientific way.

9. On faith as a theological virtue see Aquinas, Summa Theologiae II-II, qq. 1-7.

10. STh II-II, q. 2, a. 1.

11. STh II-II, q. 81.

12. Residing as it does in the will, religion is a moral virtue, not an intellectual virtue, and thus it is not directly concerned with knowing, but rather with how people should act to be virtuous.

13. STh I-II, q. 57, a. 2. Like faith, science is an intellectual virtue, and so, if there is any opposition between the two, it should be resolved in the intellect. Consequently, the relationship that should be examined critically is that between science and faith, not that between science and religion. For a historical account of the former relationship, see William A. Wallace, O.P., "A History of Science and Faith," in Transfiguration: Elements of Science and Christian Faith, ed. S. M. Postiglione (St. Louis: ITEST Faith/Science Press, 1993), 1-44.

14. Aristotle, Posterior Analytics 1.2; see also Aquinas, I Post. Anal., lect. 4-6, for his exposition of this teaching. For a clear exposition of the sense of the term "demonstration" in this context, see Melvin A. Glutz, C.P.,"Demonstration," in New Catholic Encyclopedia, ed. J. P. MacDonald, 15 vols. (New York: McGraw-Hill, 1967), 4:757-60.

15. For a fuller account of the various schools, see William A. Wallace, O.P., "Aristotle in the Middle Ages," in Dictionary of the Middle Ages, ed. J. R. Strayer, 13 vols. (New York: Charles Scribner's Sons, 1982), 1:456-69. The same divisions continued throughout the Renaissance; for details, see William A. Wallace, O.P., "Aristotle and Aristotelianism," in Encyclopedia of the Renaissance, ed. Paul Grendler, 6 vols. (New York: Charles Scribner's Sons, 1999), 1:107-13. See also "Scholasticism" in this encyclopedia by the same author, 5:422-25.

16. For a sketch of these scientific contributions, see William A. Wallace, O.P., "Thomas Aquinas," in the Dictionary of Scientific Biography, ed. C. C. Gillispie, 16 vols. (New York: Charles Scribner's Sons, 1970-1980), 1:196-200. A similar treatment of the scientific work of Aquinas's teacher, St. Albert the Great, will be found in the entry on "Albertus Magnus" by the same author in ibid., 1:99-103.

17. For details, see Frederick J. Roensch, Early Thomistic School (Dubuque, Iowa: Priory Press, 1964). There are also entries on many of these authors in the New Catholic Encyclopedia. For an overview, see the entry in that encyclopedia on "Thomism" by James A. Weisheipl; see also William A. Wallace, O.P., "Thomism and Its Opponents," Dictionary of the Middle Ages, 12:38-45. Also relevant is William A. Wallace, O.P., "Thomism and Modern Science: Relationships Past, Present, and Future," The Thomist 32 (1968): 67-83.

18. For an overview of Theodoric's life and works, see William A. Wallace, O.P., "Theodoric (Dietrich) of Freiberg," New Catholic Encyclopedia, 14:22-24; for a synoptic account of his contributions to science, see "Dietrich von Freiberg," Dictionary of Scientific Biography, 4:92-95, by the same author.

19. For a detailed account see William A. Wallace, O.P., The Scientific Methodology of Theodoric of Freiberg: A Case Study of the Relationship Between Science and Philosophy, Studia Friburgensia n.s. 26 (Fribourg: University Press, 1959). Excerpts from Theodoric's explanation of the rainbow, translated into English by the author, may be found in Edward Grant, ed., A Source Book in Medieval Science (Cambridge, Mass.: Harvard University Press, 1974), 435-41.

20. For details of Soto's research on falling motion, see William A. Wallace, O.P., "The Enigma of Domingo de Soto: Uniformiter difformis and Falling Motion in Late Medieval Physics," Isis 59 (1968): 384-401; and William A. Wallace, O.P., "Domingo de Soto's 'Laws' of Motion: Text and Context," in Texts and Contexts in Ancient and Medieval Science, ed. Edith Sylla and Michael McVaugh (Leiden: E. J. Brill, 1997), 271-304.

21. See William A. Wallace, O.P., "Domingo de Soto and the Iberian Roots of Galileo's Science," in Hispanic Philosophy in the Age of Discovery, ed. Kevin White, Studies in Philosophy and the History of Philosophy 29 (Washington, D.C.: The Catholic University of America Press, 1997), 113-29.

22. For a general account of Toledo's life and works, see William A. Wallace, O.P., "Franciscus Toletus," Encyclopedia of the Renaissance, 6:148-49.

23. These discoveries are described in summary fashion in William A. Wallace, O.P., "Galileo's Pisan Studies in Science and Philosophy," in The Cambridge Companion to Galileo, ed. Peter Machamer (Cambridge: Cambridge University Press, 1998), 27-52. For more details see William A. Wallace, O.P., Galileo and His Sources: The Heritage of the Collegio Romano in Galileo's Science (Princeton: Princeton University Press, 1984).

24. For an English translation of the physical questions, see William A. Wallace, O.P., Galileo's Early Notebooks: The Physical Questions. A Translation from the Latin, with Historical and Paleographical Commentary (Notre Dame: University of Notre Dame Press, 1977).

25. An English translation of the logical questions is now also available. See William A. Wallace, O.P., Galileo's Logical Treatises: A Translation, with Notes and Commentary, of His Appropriated Latin Questions on Aristotle's "Posterior Analytics," Boston Studies in the Philosophy of Science 138 (Dordrecht-Boston-London: Kluwer Academic Publishers, 1992). A companion volume explaining Galileo's use of these questions in his scientific work is William A. Wallace, O.P., Galileo's Logic of Discovery and Proof: The Background, Content, and Use of His Appropriated Questions on Aristotle's "Posterior Analytics," Boston Studies in the Philosophy of Science 137 (Dordrecht-Boston-London: Kluwer Academic Publishers, 1992).

26. For an account of the trial and the bearing of demonstration on its outcome, see William A. Wallace, O.P., "Galileo's Science and the Trial of 1633," The Wilson Quarterly 7 (1983): 154-64. On Galileo's science, see William A. Wallace, O.P., "Galileo's Concept of Science: Recent Manuscript Evidence, in The Galileo Affair: A Meeting of Faith and Science, ed. G. V. Coyne, M. Heller, and J. Zycinski (Vatican City: The Vatican Observatory, 1985), 15-35.

27. For details, see Walter Brandmüller and Johannes Greipl, Copernico, Galilei, e la Chiesa: Fine della controversia (1820), gli atti del Sant'Ufficio (Florence: Leo S. Olschki Editore, 1992). See note 29 below.

28. The views of Duhem, Maritain, and DeKoninck are sketched in William A. Wallace, O.P., "Toward a Definition of the Philosophy of Science," in Mélanges à la memoire de Charles de Koninck (Quebec: Les Presses de l'Université Laval, 1968), 465-485. This essay has been reprinted as "Defining the Philosophy of Science" in William A. Wallace, O.P., From a Realist Point of View: Essays on the Philosophy of Science (Washington, D.C. and Lanham, Md.: University Press of America, 1979, 1983); see the first essay in both, titled "Defining the Philosophy of Science." Vincent Edward Smith explains his position in his Philosophical Physics (New York: Harpers, 1950).

29. What follows is a synopsis of material contained in William A. Wallace, O.P., "Galileo's Trial and Proof of the Earth's Motion," Catholic Dossier 1.2 (1995): 7-13. This in turn relies heavily on the discoveries recounted in Brandmüller and Greipl, Copernico, Galilei, e la Chiesa.

30. Details are given in William A. Wallace, O.P., "Randall Redivivus: Galileo and the Paduan Aristotelians," Journal of the History of Ideas 49 (1988): 133-49.

31. See William A. Wallace, O.P., "Galileo's Early Arguments for Geocentrism and His Later Rejection of Them," in Novità Celesti e Crisi del Sapere, ed. Paolo Galluzzi (Florence: Istituto e Museo di Storia della Scienza, 1983), 31-40.

32. A full account is given in Wallace, Galileo's Logic of Discovery and Proof, 194-211.

33. An English translation of Bellarmine's letter is in Maurice A. Finocchiaro, The Galileo Affair: A Documentary History (Berkeley and Los Angeles: University of California Press, 1989), 67-69.

34. See Richard J. Blackwell, Galileo, Bellarmine, and the Bible (Notre Dame.: University of Notre Dame Press, 1991).

35. On various uses of the term suppositio, see William A. Wallace, O.P., "Aristotle and Galileo: The Uses of Hupothesis (Suppositio) in Scientific Reasoning," in Studies in Aristotle, ed. D. J. O'Meara, Studies in Philosophy and the History of Philosophy 9 (Washington, D.C.: The Catholic University of America Press, 1981), 47-77. The ways in which the demonstrative regress is used in Galileo's two formulations of the argument from the tides are given in Wallace, Galileo's Logic of Discovery and Proof, 212-16 and 228-32.

36. The main discovery here was that of Brandmüller and Greipl, Copernico, Galilei, e la Chiesa.

37. I have made this point more strongly in William A. Wallace, O.P., "Dialectics, Experiments, and Mathematics in Galileo," in Scientific Controversies: Philosophical and Historical Perspectives, ed. Peter Machamer, Marcello Pera, and Aristides Baltas (New York and Oxford: Oxford University Press, 2000), 100-124.

38. William A. Wallace, O.P., The Modeling of Nature: Philosophy of Science and Philosophy of Nature in Synthesis (Washington, D.C.: The Catholic University of America Press, 1996). See Benedict M. Ashley and Eric A. Reitan, "On William A. Wallace, The Modeling of Nature," The Thomist 61 (1997): 625-40.

39. How this is done is explained in William A. Wallace, O.P., "A Place for Form in Science: The Modeling of Nature," Proceedings of the American Catholic Philosophical Association 69 (1995): 35-46.