International Catholic University


Galileo: Science and Religion

Galileo and the Inquisition II

William E. Carroll

"The Sun's going down. Or the Earth's coming up, as the fashionable theory has it. -- Not that it makes any difference." Rosencrantz in Rosencrantz and Guildenstern are Dead by Tom Stoppard

Galileo's telescopic observations, described in The Starry Messenger and the Letters on Sunspots, provided the occasion for a renewed consideration of Copernican astronomy. At the very least, certain conclusions of traditional geocentric astronomy could no longer be maintained. Christopher Clavius, the famous Jesuit mathematician at the Collegio Romano, had written as early as 1611 that as a result of what Galileo had discovered and what he himself had seen through the telescope, astronomers will now have "to consider how the celestial orbs may be arranged in order to save these phenomena."

As we have seen, an understanding of the encounter between Galileo and the Inquisition requires that we keep in mind the question of the scientific status of the claim that the Earth revolves about the Sun. I have already indicated that Galileo and Cardinal Bellarmino understood science in the Aristotelian sense, as sure and certain knowledge of what is so: knowledge, the certainty of which is guaranteed by a causal nexus. As the discussion of Copernican astronomy moved increasingly into the arena of theology -- and, in particular, into the realm of what the Bible was said to reveal on the subject -- Galileo was concerned that the Church might be persuaded (or persuade itself) to condemn the new astronomy.

We know that, by 1615, Galileo was convinced that he was on the verge of achieving a demonstration for the motion of the Earth, but he needed time. He sought to prevent the Church from making a foolish mistake: condemning as heretical the claim that the Earth moves, when he was about to demonstrate that in fact the Earth does move. Galileo expected that an argument from the phenomenon of the tides would provide the necessary demonstration. He circulated a manuscript on this subject in late 1615 and early 1616, and the argument appears in the final section of his Dialogue Concerning the Two Chief World Systems, published in 1632. But in 1615 and 1616, Galileo did not think that he yet had the requisite demonstration. There is some debate among Galileo scholars as to whether he eventually thought that he was able to demonstrate the motion of the Earth from the fact of the ocean tides; I think that Galileo came reluctantly to the conclusion, by the 1620's, that he didn't have such a demonstration, although he found the argument ingenious and included it in the Dialogue.

In any event, in 1615 and 1616 neither Galileo nor the Inquisition thought there was a demonstration for the motion of the Earth: Galileo expected, indeed anticipated, one; the Inquisition did not. In the absence of a demonstration for the motion of the Earth, Cardinal Bellarmino had urged prudence: do not challenge the traditionally accepted readings of those biblical passages which have been interpreted as affirming the immobility of the Earth. The cardinal was acutely aware of the Protestant challenges to the Catholic Church's claim to be the sole, legitimate interpreter of God's word. In many ways we see the Inquisition especially concerned with maintaining the authority of the Church against all who seemed to threaten it. Bellarmino, veteran of theological controversies with Protestants, was always alert to point out that the principal theological issue of the day with respect to the Bible was not so much what Scripture meant as who had the authority authentically to interpret it. For the cardinal "the protection of the Church's interpretive authority was a separate and more basic issue than the specific question of whether the motion of the Sun and the stability of the Earth should be taken as simply literal or figurative. . . . The individual judge of Scripture (e.g., Galileo or Foscarini) faced a double jeopardy; one relating to the content of the interpretation, the other to assuming the role of interpreter." [Blackwell, pp. 36-7] No matter what the merits of the interpretation offered, the individual was always subject to the suspicion that he was usurping the Church's divinely established role as the guardian of God's word.

During the momentous years of 1615 and 1616, as the discussion about the relationship between the new astronomy and the Bible reached into the highest circles of the Catholic Church, Galileo was increasingly concerned at the authorities in the Church might act foolishly and conclude that there was an incompatibility between heliocentric astronomy and the Bible.

We can see the general outline of Galileo's position in the notes he wrote to himself as he sketched his response to Bellarmino's letter to Foscarini:

The motion of the earth and the stability of the sun could never be against Faith or Holy Scripture, if this proposition were correctly proved to be physically true by philosophers, astronomers, and mathematicians, with the help of sense experience, accurate observations, and necessary demonstrations. However, in this case, if some passages of Scripture were to sound contrary, we would have to say that this is due to the weakness of our mind, which is unable to grasp the true meaning of Scripture in this particular case. This is the common doctrine, and it is entirely right, since one truth cannot contradict another truth. On the other hand, whoever wants to condemn it judicially must first demonstrate it to be physically false by collecting the reasons against it. . . . If the earth de facto moves, we cannot change nature and arrange for it not to move. But we can rather easily remove the opposition [la repugnanza] of Scripture with the mere admission that we do not grasp its true meaning [il suo vero senso]. Therefore the way to be sure not to err is to begin with astronomical and physical investigations, and not with scriptural ones. [Finocchiaro, pp. 80-2]

Galileo addresses the question of the relationship between science and the Bible in his most extensive and systematic way in his famous "Letter to the Grand Duchess Christina." Galileo is the chief scientist in the employ of the Medici family and Christina of Lorraine is the mother of the reigning Grand Duke. The letter contains Galileo's account of the recent controversy over the claims of Copernican astronomy. He composes it in 1615, after having read Bellarmino's response to Foscarini, and, as I mentioned, in the midst of the debate concerning the relationship between traditional interpretations of the Bible and the view that the Earth moves.

By addressing the letter to the Grand Duchess, rather than to theologians in Rome, Galileo is able to write to an educated lay audience, even though his primary audience are the authorities of the Inquisition in Rome. Galileo is neither a bishop nor a theologian, and theologians in Rome might well dismiss a theological treatise addressed to them by Galileo the mathematician and physicist.

Galileo is well-trained in Renaissance techniques of rhetoric and a failure to recognize Galileo's rhetorical techniques has resulted in uncritical reading of the letter. For example, many modern history texts accept without question Galileo's own account of the history of the controversy, which he presents in the first few paragraphs of the letter. We must remember when we read his account that, first of all it is his interpretation of the events, and, second, that he has chosen his facts carefully in order to achieve his end: to persuade the authorities of the Catholic Church not to act foolishly and condemn Copernican astronomy.

He identifies his enemies as being unable to refute him in science, and as a result, they "try to shield the fallacies of their arguments with the cloak of simulated religiousness and with the authority of Holy Scripture, unintelligently using the latter [the Bible] for the confutation of arguments they neither understand nor have heard." The story he tells of Copernicus is also interesting. He misidentifies him as a priest, argues that his investigations were undertaken at the request of the Pope, and, noting that Copernicus' book was dedicated to the Pope, Galileo claims: "Once printed this book was accepted by the Holy Church, and it was read and studied all over the world without anyone's ever having the least scruple about its doctrine." Galileo concludes his historical observations with the following remark:

Finally, now that one is discovering how well founded upon clear observations and necessary demonstrations [quanto ella sia ben fondata sopra manifeste esperienze e necessarie dimostrazioni] this doctrine is, some persons come along who, without having seen the book, give its author the reward of so much work by trying to have him declared a heretic; this they do only in order to satisfy their special animosity, groundlessly conceived against someone else [Galileo, himself] who has no greater connection with Copernicus than the endorsement of his doctrine.

Note what Galileo claims and what he does not claim. His comments, at first glance, suggest that Copernican astronomy has been demonstrated to be true, or perhaps has been shown to be true on the basis of "clear observations" [manifeste esperienze], no doubt Galileo's telescopic discoveries. But on closer inspection, we see that all Galileo is claiming is that Copernican astronomy is "well founded upon clear observations and necessary demonstrations." To show that a position is "well founded" is not necessarily to show that it has been demonstrated to be true. Galileo is aware of the importance of necessary demonstrations; he has in mind Bellarmino's distinctions in the Cardinal's letter to Foscarini. In fact, throughout the "Letter to the Grand Duchess," Galileo uses the phrase "necessary demonstrations" frequently, without once offering such a demonstration for the motion of the earth. Remember the rhetorical nature of the Letter; Galileo seeks to persuade the officers of the Inquisition not to condemn Copernican astronomy. Galileo knows that theologians in Rome accept the position that the truths of science and the truths of faith cannot contradict one another, and that, if there is a scientific demonstration on a particular subject, it would not be possible for the Bible to be authentically interpreted in a way which contradicts what science demonstrates. Remember, in addition, that both Galileo and the officers of the Inquisition share the same Aristotelian ideal of scientific knowledge; both sides understand what a demonstration is. If Galileo, in fact, had a demonstration for the motion of the earth, he surely would have presented it, for he knew that a demonstration would prevent the Church's condemnation of Copernican astronomy. We see here another reason for ostensibly addressing the letter to the Grand Duchess, for she would not be expected to follow a complex scientific demonstration; it would be sufficient for her chief scientist simply to suggest that one existed. Throughout the "Letter to the Grand Duchess," Galileo reaffirms traditional Catholic teaching on the relationship between science and scripture. God is the author of both the book of nature and the book of scripture. Therefore, the truths of nature and scripture cannot contradict one another. [verum cum vero congruit] Accordingly, Galileo writes:

I think that in disputes about natural phenomena one must begin not with the authority of scriptural passages, but with sensory experiences and necessary demonstrations. For the Holy Scripture and nature derive equally from the Godhead, the former as the dictation of the Holy Spirit and the latter as the obedient executrix of God's orders; moreover, to accommodate the understanding of the common people it is appropriate for Scripture to say many things that are different in appearance and in regard to the surface meaning of the words from the absolute truth . . . and so it seems that natural phenomena which are placed before our eyes by sensory experience or proved by necessary demonstrations should not be called into question, let alone condemned, on account of scriptural passages whose words appear to have a different meaning.

One must know how to discover the true meaning of Scripture since this does not always correspond to the surface meaning of the words (il nudo significato delle parole). Furthermore, we must remember that the primary purpose of the Bible is not to reveal how the heavens go, but how to go to heaven. In his attempt to persuade the Inquisition not to condemn Copernican astronomy, Galileo asks rhetorically: "can an opinion be both heretical and irrelevant to the salvation of souls?" Cardinal Bellarmino might well respond that there are different senses of "irrelevant." It may well be that, from the point of view of the subject matter, an astronomical claim is irrelevant to salvation, but if this issue is discussed in the Bible then the question is relevant to salvation in that it is a matter of faith that the Bible is true from beginning to end. We have seen, however, that Cardinal Bellarmino understands that the true meaning of the Bible may be difficult to discern in a particular instance; the Cardinal is well aware that the true meaning of the text may be expressed in metaphors and similes. For example, when the Bible refers to God's stretching out His hand, the true meaning of the text concerns God's power since God does not have a body.

Galileo does recognize the authority of the Church to determine the true meaning of the Bible, but he urges those in Rome to beware of the mischievous advice and that the Church should not "flash the sword [simply because she] . . . has the power to do it, without considering that it is not always right to do all that one can do." Galileo argues that it is contrary to Catholic practice "to use scriptural passages to establish conclusions about nature, when by means of observation and necessary demonstrations one could at some point demonstrate the contrary of what the surface meaning of the words affirm."

Galileo quotes famous Catholic theologians, most notably, St. Augustine, and he leaves these quotations in the authoritative, original Latin. He finds support for the continuity of his views with Catholic orthodoxy in passages from Augustine's On the Literal Meaning of Genesis such as this one: "In obscure subjects very far removed from our eyes, it may happen that even in the divine writings we read things that can be interpreted in different ways by different people, all consistent with the faith we have; in such a case, let us not rush into any one of these interpretations with such precipitous commitment that we are ruined if it is rightly undermined by a more diligent and truthful investigation." [I.18]

Another passage from Augustine serves Galileo's purposes well: "There should be no doubt about the following: whenever experts of this world can truly demonstrate something about natural phenomena, we should show it not to be contrary to our Scripture; but whenever in their books they teach something contrary to the Holy Writ, we should without any doubt hold it to be most false and also show this by any means we can. . . ." [On the Literal Meaning of Genesis I.21] After citing this text from Augustine, Galileo employs a particularly deft argument: the words of St. Augustine imply

. . . the following doctrine: in the learned books of worldly authors are contained some propositions about nature which are truly demonstrated and others which are simply taught; in regard to the former [those truly demonstrated], the task of wise theologians is to show that they are not contrary to Holy Scripture; as for the latter (which are taught but not demonstrated with necessity), if they contain anything contrary to the Holy Writ, then they should be considered indubitably false and must be demonstrated such by every possible means.

In which of these two categories would one put the argument for the motion of the Earth in 1615? Galileo is so certain that he is about to have a demonstration for the motion of the Earth that he grants to the Bible an authority on scientific matters that both Augustine and Aquinas would deny. Perhaps he thought that such obeisance to biblical authority on his part might ingratiate him to the Inquisition in Rome. In fact, in a rather clever move, Galileo seems to turn the tables on the Inquisition: "therefore, before condemning a physical proposition, one must show that it is not conclusively demonstrated. Furthermore, it is much more reasonable and natural that this be done not by those who hold it to be true, but by those who regard it to be false . . . ."

You might imagine how a theologian in Rome would evaluate Galileo's argument. Despite all the rhetoric of necessary demonstrations, one searches the letter in vain to find one. Rather than providing a scientific demonstration, Galileo expects theologians to enter the arena of science to show that a particular proposition is not "conclusively demonstrated."

In the eighth and final lecture, on Galileo as theologian, I will return to the arguments Galileo set forth in this letter and will examine the widely accepted view that he embraces a modern distinction between science and religion. For now I wish to ask, in the light of so many shared views about the nature of scientific demonstration, the absence of such a demonstration for the motion of the Earth, the ancient Catholic commitment that the truths of science and the truths of faith cannot contradict one another, how it is that what was for Cardinal Bellarmino prudential advice, to consider Copernican astronomy purely as an hypothesis, was transformed in 1616 to an explicit injunction to Galileo not to hold, teach, or discuss Copernican astronomy?

In early 1616 the cardinals of the Inquisition instruct their theological consultants formally to consider the status of the new astronomy in the light of biblical revelation. In February 1616 the consultants reach the conclusion that the propositions of Copernican astronomy concerning the mobility of the Earth and the immobility of the Sun are false and heretical. We will return to examine again the conclusions of the theological experts in the final lecture on Galileo as theologian, but for now we should note that a report of theological consultants does not constitute Church doctrine. Furthermore, the theologians first conclude that the claims that the Sun is immobile and the Earth moves are false scientifically, and then they conclude that these propositions are heretical in that they contradict the literal sense of the Bible. As I mentioned in my initial lecture, the theologians do not conclude that these scientific claims are false because they contradict the Bible: that is, they do not subordinate scientific claims to biblical authority. Rather, they come to understand what they consider to be the true sense of the Bible after they have concluded that the new astronomy is false on scientific grounds. On the basis of these findings, the Inquisition orders Galileo not to hold, teach, or defend such propositions, and the text of Copernicus must no longer be published until it is corrected. The corrections eventually ordered by the Index of Forbidden Books involve changing those passages in which Copernicus claims that in fact the Earth moves to read that he simply supposes or hypothesizes that the Earth moves. The order for the correction of Copernicus' text is instructive: "If certain of Copernicus' passages on the motion of the Earth are not hypothetical, make them hypothetical; then they will not be against either the truth or the holy writ. On the contrary, in a certain sense, they will be in agreement with them, on account of the false nature of suppositions, which the study of astronomy is accustomed to use as its special right." The distinction between speaking hypothetically and speaking absolutely, which Bellarmine had urged upon Galileo in April 1615, as prudential advice, now serves as the basis for the disciplinary decrees of the Inquisition and the Index of Forbidden Books. The theologians of the Inquisition, committed as they were to the complementarity between science and scripture, accepted as obviously true a particular geocentric cosmology, and, on the basis of such a commitment, insisted that the Bible must be read in a certain way. Furthermore, just as some philosophers mistakenly concluded that Aristotelian physics and metaphysics depended on a geocentric cosmology, so some theologians feared that, a rejection of Aristotle's view that the Earth does not move, would call into question all of Aristotelian philosophy, a philosophy upon which important elements of Catholic theology depended. Catholic theologians, for example, had long employed Aristotelian physics in their exposition of the doctrine of transubstantiation. The role of Eucharistic theology in the Galileo Affair has been the subject of considerable interest since the publication of Pietro Redondi's book, Galileo eretico, in 1983. Redondi's thesis concerns theological objections to atomistic physics found in Galileo's Assayer, which was published in 1623. In some respects, Redondi is reiterating a claim made by Thomas Campanella in 1622: "The first argument against Galileo is that it seems that theological doctrines would be completely overthrown by anyone who tries to introduce new ideas which are contrary to the physics and metaphysics of Aristotle, on which St. Thomas and all the Scholastics based their theological writings." [A Defense of Galileo (trans. by Richard Blackwell, U. of Notre Dame Pres, 1994), p. 43] We will consider Redondi's thesis in some detail in the next lecture.

What is clear in the actions of 1616 is that the theologians of the Inquisition thought that the Bible contained scientific truths. Since it was obvious, from science, that the Earth does not move, and since certain passages in the Bible seemed clearly to say or to imply the same thing, it must be the case that the Bible proclaims that the Earth does not move. Furthermore, in the face of the Protestant Reformation, the Catholic Church was particularly alert to threats, real or imagined, to traditional interpretations of the Bible and to the authority of the Church to determine the true meaning of the Bible.

The Inquisition did not think that it was requiring Galileo to choose between faith and science. Nor, in the absence of scientific knowledge for the motion of the Earth, would Galileo have thought that he was asked to make such a choice. One week after learning of the 1616 decision of the Inquisition, Galileo wrote to the Secretary of State to the Grand Duke of Tuscany to inform him as to what had transpired. Galileo had been in Rome since December 1615, hoping to use his influence to prevent the condemnation of Copernican astronomy. He was acutely aware that some Florentine theologians had accused him of affirming a position that was "heretical and against the faith." Galileo observed that his opponents "tried orally and in writing to make this idea prevail, but events have shown that [this] . . . effort did not find approval with the Holy Church. She [the Church] has only decided that the opinion does not agree with Holy Scripture, and thus only those books are prohibited which have explicitly maintained that it does not conflict with Scripture." [6 March 1616] Although Galileo did not mention in this letter the specific injunction communicated to him, it seems that he did not view what transpired to be as serious as it has since been interpreted. In May 1616 Galileo obtained a formal statement from Cardinal Bellarmino concerning what had happened when the Cardinal had informed Galileo of the Inquisition's orders to him in March of that year. According to Bellarmino, Galileo had not been required to recant any views he held; "he [Galileo] has only been notified of the declaration made by the Holy Father and published by the Sacred Congregation of the Index, whose content is that the doctrine attributed to Copernicus (that the earth moves around the sun and the sun stands at the center of the world without moving from east to west) is contrary to Holy Scripture and therefore cannot be defended or held." [Finocchiaro, p. 153]

The famous trial of Galileo in 1633, after the publication of his Dialogue Concerning the Two Chief World System, depends on the decisions reached 17 years earlier. The theological, philosophical, and scientific questions which constitute the heart of the controversy are clear by 1616. The Inquisition expected Galileo to obey their orders not to hold, teach, or defend Copernican astronomy. The cardinals who sat in judgment of Galileo in 1633 were convinced that he had violated that injunction and they demanded that he formally renounce the views proscribed seventeen years before.

Texts Cited

Blackwell, Richard J. Galileo, Bellarmine, and the Bible. University of Notre Dame Press, 1991.

Fantoli, Annibale. Galileo: for Copernicanism and for the Church. (translated by George Coyne), second edition. Vatican Observatory Publications, 1996.

Finocchiaro, Maurice A. (ed.) The Galileo Affair: A Documentary History. The University of California Press, 1989.

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