Science Against Copernicus in the Age of Galileo

Tycho Brahe’s objections to the Copernican system retained currency in the world system debate in the period between the advent of the telescope and Riccioli’s New Almagest. The “star size objection” can be found in writings from this period by Johann Georg Locher, Francesco Ingoli, and Philips Lansbergen. Locher and Ingoli were both anti-Copernicans whose ideas Galileo criticized in some detail in his writings. Both referenced Tycho when arguing for Earth’s immobility. Lansbergen, on the other hand, was a prominent Copernican who adapted Tycho’s star size objection into a religious argument for the superiority of the Copernican system. Locher, Ingoli, and Lansbergen illustrate not only that Tycho’s objections remained part of the debate, but they also illustrate a surprising aspect of that debate: anti-Copernican reliance on “scientific” arguments to support their views, and Copernican reliance on “religious” arguments to support theirs.

Johann Georg Locher (1592–1633) was a student of Christopher Scheiner, who in turn was a Jesuit and professor of mathematics at Ingolstadt. In 1614 Locher published a book entitled Mathematical Disquisitions on Controversial and Novel Astronomical Topics. Galileo in his Dialogue discusses Locher’s book extensively. William Donahue describes Locher and Scheiner as influential Jesuit scientists who sought to renovate astronomical ideas rather than build them anew, and who accepted telescopic discoveries and applied their own explanations to them. Indeed, in the Disquisitions, Locher discusses and elaborately illustrates various telescopic discoveries, such as the rugged lunar surface and spots on the Sun. He includes a fold-out illustration of how the telescopically discovered phases of Venus indicate that it circles the Sun. But he does not accept the Copernican system.

Locher provides six key arguments against Copernicus. The first of these makes a partial reference to matters of religion, namely, that the Copernican system requires that many passages of sacred scripture, and many astronomers’ common ways of speaking, be twisted in a preposterous sense. He elaborates on this colorfully:

Because of the arrangement of the parts of the Universe and the imagined motion of Earth in this hypothesis, the Sun, Mercury, and Venus are below, and Earth is above. Heavy bodies absolutely and naturally ascend—light bodies descend. Christ the Lord ascended to hell, and descended to the heavens, at which time he approached the Sun. When Joshua commanded the Sun to stand still, actually the Earth stood still, or the Sun moved contrarily to earth. When the Sun dwells in Cancer, the Earth runs through Capricorn, and generally the winter zodiac signs bring about the summer, and the summer the winter. The stars do not rise and set to Earth, but Earth to the stars—the stars’ rising becomes the Earth’s setting, the stars’ setting becomes the Earth’s rising. In short, the whole course of the World, as it were, is inverted.

Yet, acknowledges Locher, “The Copernicans may answer arguments like these adequately but convolutedly.” In other words, arguments about how the Copernicans invert the meaning of astronomical or scriptural texts carry little weight. Copernicans can answer them, even if the answers seem convoluted. However, says Locher, “they will not be able to satisfy so well the arguments that follow.” He has other arguments he says the Copernican cannot answer.

And what is the next key argument Locher provides? The star size argument. Locher says that the Copernican motion of the Earth makes any first-magnitude star well larger than the whole orbit of the Earth, and makes any small star just as large. Locher cites Tycho, providing books and page numbers, in his discussion of this argument. The remaining four key arguments consist of one argument about the inelegance of the Copernican system (the vast distance of the stars serves no purpose, other than to explain the lack of parallax) and three about the Copernican system being in conflict with the Aristotelian physics of motion. Thus to Locher, the question of scripture makes up but half of a lightweight argument against Copernicus. The weighty anti-Copernican arguments are questions of science: star sizes, star distances, and physics. Yet, in light of the telescopic discoveries of Galileo, says Locher, a system is needed that can accommodate Venus circling the Sun—a hybrid geocentric system like that of Tycho Brahe.

Just two years after Locher’s Disquisitions, in January of 1616, Monsignor Francesco Ingoli (1578–1649) addressed Galileo with an essay entitled “Disputation Concerning the Location and Rest of Earth against the System of Copernicus,” which echoed Locher to some extent. In this essay Ingoli presents a greater number and wider variety of arguments against the Copernican hypothesis than Locher does in Disquisitions. Ingoli describes the arguments as mathematical, physical, and theological. But, like Locher, he puts emphasis on the questions of science: mathematical (i.e., astronomical) and physical arguments.

In his closing paragraph, Ingoli suggests that Galileo focus on those arguments, rather than on the theological arguments, and then only on the “more weighty” among them. Like Locher, Ingoli also relies on the work of Tycho Brahe. Many of the essay’s mathematical and physical arguments reference Tycho’s book Astronomical Letters, often including page numbers.

Galileo believed Ingoli’s essay to have been influential in the infamous condemnation of the Copernican hypothesis by a committee of consultants for the Roman Inquisition in February 1616. Thus Ingoli’s emphasis on weighty mathematical and physical arguments (that is, “scientific” arguments) rather than on theological arguments, his reliance on the work of Tycho, and even his inclusion of theological arguments, which he then deemphasizes, all suggest an overlooked aspect of the Inquisition’s opposition to Copernicus. Unsurprisingly, among those arguments of Tycho that Ingoli cites are the cannon at the equator and poles argument, and of course, the star size objection.

Ingoli was a well-connected clergyman who had engaged Galileo in debates at the home of Lorenzo Magalotti (1584–1637). After one of their oral debates, the two agreed to put their arguments into writing, with Ingoli doing so first and Galileo responding. Thus, Ingoli produced the essay. Maurice Finocchiaro writes that this essay was “one of the most complete, intellectually ambitious, and historically significant” of the anti-Copernican critiques produced at the time of Galileo’s telescopic discoveries. It was not published, but it was circulated widely.

Finocchiaro continues that Ingoli “had probably been commissioned by the Inquisition to write an expert opinion on the controversy” and that this opinion “provided the chief direct basis for the recommendation by its committee of consultants that Copernicanism was philosophically untenable and theologically heretical.” Galileo was of the opinion that the essay played an important role in in the rejection of the Copernican hypothesis by church authorities in Rome.

In a reply to the essay that he wrote to Ingoli in 1624, he notes that Ingoli’s arguments “were not lightly regarded by persons of authority who may have spurred the rejection of the Copernican opinion.” He worries about Ingoli’s essay having “circulated in various foreign nations” and about people thinking “that the rejection of Copernicus’s opinion was based on a belief that you [Ingoli] were right.” While the essay may have circulated, it was not published until the end of the nineteenth century, in Antonio Favaro’s Opere di Galileo. Translations into English are scarce.  

Ingoli’s essay may indeed have been important in the rejection of the Copernican hypothesis by Church authorities, but at the time he wrote the essay, that rejection was yet to occur. The Dominican friar Niccolò Lorini (1544– ca. 1617) had filed a complaint against Galileo with the Inquisition in Rome in February 1615. That complaint was investigated by the Inquisition during 1615, and Galileo had gone to Rome in December 1615 in hopes of clearing his name and preventing the condemnation of the Copernican hypothesis. It was in the month following Ingoli’s essay, on 24 February 1616, that the Inquisition’s committee of consultants issued their opinion condemning the Copernican hypothesis as “foolish and absurd in philosophy.”

This was promptly followed by a meeting on 26 February between Galileo and Cardinal Robert Bellarmine (1542–1621) in which Bellarmine purportedly warned Galileo that “the doctrine attributed to Copernicus . . . is contrary to Holy Scripture and therefore cannot be defended or held.” Then on 5 March the Congregation of the Index (the department within the Vatican in charge of book censorship) issued a decree rejecting the Copernican hypothesis as “false” and “altogether contrary to Holy Scripture". Thus Ingoli’s essay just preceded the rejection.

Ingoli opens the essay with a “preface” in which he makes reference to the discussions before Magalotti regarding the Copernican hypothesis, noting that Galileo has been the defender of Copernicus, while he (Ingoli) has been given the role of defending the other side—bringing forth arguments to support the hypothesis of the “old mathematicians” and to tear down the Copernican assumption. He says he has agreed to his role willingly, because he is grateful and honored to be debating with and learning from educated men such as Galileo.

The body of Ingoli’s essay consists of anti-Copernican arguments, which we will discuss presently. However, Ingoli closes the essay with a short paragraph that is a particularly interesting feature of the essay and that illuminates the arguments. Thus it needs to be presented in its entirety here first:

These [arguments] complete this disputation. Let it be your choice to respond to this either entirely or in part—clearly at least to the mathematical and physical arguments, and not to all even of these, but to the more weighty ones. For I have written this not toward attacking your erudition and doctrine (most notable to me and to all men both inside the Roman Curia and outside), but for the investigation of the truth, which you profess yourself always to search for by all strength, and in fact so suits a mathematical talent.

Indeed, when Galileo wrote his response to Ingoli in 1624, he only responded to Ingoli’s mathematical and physical arguments. He did, however, respond to every one of those, in great detail. Galileo’s reply, despite the absence of responses to the theological arguments, is over twenty thousand words in length; Ingoli’s essay has a length of approximately three thousand words.

Ingoli presents Galileo with five physical arguments against Copernicus, most of which deal with the fact that the Copernican hypothesis conflicts with the Aristotelian physics of motion. He presents Galileo with thirteen mathematical anti-Copernican arguments. These cover a wide range of subjects, and are of uneven quality, but it is here that we find Tycho’s arguments about the cannon at the poles and equator, and about star sizes.

The star size argument features prominently in Ingoli’s essay, yet he does not put it forth as one of the thirteen mathematical arguments per se. Rather, he puts it into a special discussion that follows the second and third mathematical arguments, both of which have to do with matters related to parallax. These two arguments cite two different noticeable effects that would be visible in the fixed stars were the Earth not in the center of the universe (as it would not be, were it orbiting the Sun). The Copernican answer to such arguments is that the orbit of Earth is of negligible size compared to the distance to the stars. At this point Ingoli brings in the star size question, saying,

Nor does the solution [to the two parallax arguments] entirely satisfy by which is said: the diameter of the circle of the orbit of Earth in comparison to the vast distance of the eighth orb from us to be made so small [as to yield an effect too small to measure].

He then cites a page of Tycho’s Astronomical Letters as well as his calculations showing how distant the stars would have to be in the Copernican system for annual parallax to be too small to detect. Here is the very first time that Ingoli mentions Tycho Brahe in the essay—when he brings out Tycho’s toughest anti-Copernican argument. Ingoli continues:

Such a truly great distance not only shows the universe to be asymmetrical, but also clearly proves . . . the fixed stars to be of such size, as they may surpass or equal the size of the orbit circle of the Earth itself.

For these reasons, Ingoli says, the parallax arguments cannot be dismissed by the Copernican assertion that the stars are so distant. And neither, we may presume, can the other arguments that involve the effects of Earth’s motion seen in the stars (the seventh and eighth mathematical arguments are such arguments).

In his 1624 reply, Galileo answered that the telescope showed stars to measure much smaller in diameter than Tycho had measured with non-telescopic instruments: seen with a telescope, the stars were revealed to be less than a tenth the size Tycho had measured. But in 1614 Simon Marius had stated in his book The World of Jupiter that telescopic observations of the stars argued for a Tychonic world system, and by 1624 Galileo’s own (unpublished) telescopic observations of stars had apparently shown Tycho’s star size objection to be valid still.

Remarkably, Ingoli actually suggests to Galileo the solution to Tycho’s argument. Ingoli suggests, in essence, that the apparent sizes of the stars are spurious. In the “such a truly great distance” quote above, Ingoli says that the great distance either proves the fixed stars to be of enormous size, or, he says (at the point of the ellipses between “clearly proves” and “the fixed stars”), it proves that the fixed stars, on account of their great distance, do not function like other celestial bodies seen from Earth.

He offers as an analogy that the Sun has less effect the further it is from the zenith (in winter versus in summer). In his 1624 reply, Galileo interprets this statement as Ingoli saying that if the stars were vastly distant it would destroy their ability to affect things on Earth (perhaps in an astrological sense), but Ingoli is clearly speaking in regards to the apparent sizes of stars:

Such a truly great distance not only shows the universe to be asymmetrical, but also clearly proves, either the fixed stars to be unable to operate in these lower regions, on account of the excessive distance of them; or the fixed stars to be of such size, as they may surpass or equal the size of the orbit circle of the Earth itself.

A loose paraphrase might read, “either the stars must be huge, or something doesn’t work like we think it does.” Ingoli was right—as regards stars, something indeed did not work like they thought it did. Ingoli devoted less space to Tycho’s cannon at the equator and poles argument. Citing the appropriate pages from the Astronomical Letters, Ingoli notes Tycho’s argument

. . . concerning the bombards discharged from the east into the west and from the north into the south, particularly concerning those discharged near the poles, where the movement of Earth is slowest. For, given the diurnal motion of Earth, the most apparent differences would be observed, whereas nevertheless no differences are observed.

This is Ingoli’s sixth mathematical argument. Almost all the mathematical arguments cite Tycho in some way. Ingoli also includes four theological arguments in his essay, although, as seen earlier, he suggests Galileo bypass them in favor of the mathematical and physical ones, which Galileo does in his 1624 reply. These arguments concern how the words in scripture describe a geocentric structure to the heavens, how hell (in the center of the Earth) should be at the farthest point from heaven, how Joshua commanded the sun to stand still, and how geocentric language is used in certain prayers.

Interestingly, Riccioli would include within his 1651 New Almagest a discussion of 126 pro- and anti-Copernican arguments much lengthier than Ingoli’s. Only two of the 126 would be of a religious or scriptural or theological nature. One of those two would be the same argument about the placement of heaven and hell that Ingoli presents to Galileo. Riccioli would dismiss this argument because, he would say, hell is a place defined in comparison to God’s heaven and the world of men; whether the Earth has motion or not is irrelevant. The theological arguments also feature Cardinal Robert Bellarmine prominently. Ingoli specifically mentions him in conjunction with the second and fourth theological arguments.

But theological arguments in the essay about hell or scriptural language are outnumbered more than four to one by mathematical and physical arguments—by “scientific” arguments (in Locher’s Disquisitions they are outnumbered five and one-half to one-half). These scientific arguments, and in particular the more weighty ones, are those Ingoli suggests Galileo focus on. They are not all equally weighty. At least one is easily dismissed. But the others are better, some are much better, and those taken from Tycho Brahe’s book Astronomical Letters would carry a significant weight owing simply to the authority of their illustrious author.

Ingoli cites Tycho repeatedly in the essay—far more frequently than he cites older sources such as Aristotle or Ptolemy. Despite Ingoli’s remark in the preface about his defending the “old mathematicians,” it is not the ancient works of Aristotle and Ptolemy that Ingoli brings to bear against Copernicus, but the recent works of Tycho, the leading astronomer of the time. It is Tycho, not Aristotle and Ptolemy, that Ingoli sees as being the competition for Copernicus.

Tycho’s arguments not only carried the weight of the authority of the leading astronomer of the time, but they were also—in light of the knowledge of the time—strong, valid arguments. Tycho’s challenging cannon-at-the-equator-and-poles argument, for example, was one that Galileo failed to adequately answer in his 1624 reply to Ingoli, and presumably Galileo could not have answered it in 1616 either. And, of course, Ingoli included in his essay a special discussion of Tycho’s strongest argument: star sizes. Ingoli recognized what was the weightiest argument in the essay, probably because Tycho had recognized it as such.

Riccioli, in his New Almagest analysis of 126 pro- and anti-Copernican arguments, dismissed the vast majority of the arguments on either side as being inconclusive (and sometimes even fatuous)— with the exception of two classes of arguments. First and foremost of these two were arguments involving the apparent sizes of stars. And then, secondarily, were arguments related to the matter of the cannon at the equator and poles. These arguments could not be answered (at the time), and the inability to answer them would be explicitly recognized by Riccioli.

In light of these strong scientific arguments, the purpose of the theological arguments (downplayed by Ingoli and bypassed by Galileo) seems twofold. One purpose seems to be to convey a sense of Cardinal Robert Bellarmine’s views on the matter, as two of the theological arguments mention him. The other seems to be to emphasize how the words of scripture fit a geocentric universe. Ingoli notes in discussing the third theological argument that, “in explaining Sacred Writings the rule is to always save the literal sense, when it can be done,” echoing Augustine and Aquinas. Bellarmine had emphasized this point some months earlier in April 1615, stating in a letter that if solid evidence for the Copernican system were found, then the literal sense of scripture would have to give way to a different interpretation:

I say that if there were a true demonstration that the sun is at the center of the world and the earth in the third heaven, and that the sun does not circle the earth but the earth circles the sun, then one would have to proceed with great care in explaining the Scriptures that appear contrary, and say rather that we do not understand them than that what is demonstrated is false. But I will not believe that there is such a demonstration, until it is shown me.

He continues:

Nor is it the same to demonstrate that by supposing the sun to be at the center and the earth in heaven one can save the appearances, and to demonstrate that in truth the sun is at the center and the earth in heaven; for I believe the first demonstration may be available, but I have very great doubts about the second, and in the case of doubt one must not abandon the Holy Scripture as interpreted by the Holy Fathers.

Bellarmine had apparently held this sort of view about scripture and astronomy for decades. It seems to have been common in Jesuit circles, but the French Jesuit Honoré Fabri (1607–1688) was apparently the first to publish it, writing in 1661 that:

Nothing hinders that the Church may understand those Scriptural passages that speak of this matter in a literal sense, and declare that they should be so understood as long as the contrary is not evinced by any demonstration.

And he continued on to say that if some demonstration of the validity of the Copernican hypothesis were found, the Church would not scruple to declare that those passages are to be understood in a figurative sense.

Thus Ingoli seems to be stating that the theological arguments only come into play if the science allows—that is, “when it can be done.” If the science is clearly against scripture, then the interpretation that “Scripture may speak following our manner of understanding” must be invoked. It is understood that scripture does not assert that the value of pi is three when it describes a round pool of water whose circumference is three times its diameter. Nor does scripture make the scientific assertions that the world is flat with four corners or that no seeds are smaller than mustard seeds. Ingoli can suggest that Galileo pass over the theological arguments and focus on the more weighty of the scientific arguments, because the crux of the matter is scientific.

But science in 1616 is not clearly against scripture: according to Tycho Brahe, the top expert in the field, the science does not support the Copernican system. Indeed, Tycho believed it to be absurd. Thus, the literal sense of scripture can still be retained, and the Copernican system, in contradicting that literal sense, is “heretical.”

Ingoli’s reliance on Tycho Brahe, and Ingoli’s suggestion that Galileo ignore his theological arguments, as well as Locher’s use of Tycho’s ideas and his minimal focus on scriptural arguments, again raise a question regarding the manner in which opposition to the Copernican system is often depicted. Namely, such opposition is typically portrayed as a matter of adherence to Aristotle or to religion, as Albert Einstein put it, “anthropocentric and mythical thinking.” It is not often depicted as a matter of valid scientific arguments, supported by detailed references to works by a leading scientist.

EDITORIAL NOTE: This essay is an excerpt from Setting Aside All Authority: Giovanni Battista Riccioli and the Science against Copernicus in the Age of Galileo. It is part of an ongoing collaboration with the University of Notre Dame Press. You can read our excerpts from this collaboration here. ALL RIGHTS RESERVED.

Featured Image: Jan Matejko, Copernicus's Conversation with God, 1872; Source: Wikimedia Commons, PD-Old-100. 


Christopher Graney

Christopher Graney is an adjunct scholar at the Vatican Observatory. His most recent book is Mathematical Disquisitions: The Booklet of Theses Immortalized by Galileo.

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