When Galileo mentions “necessary demonstrations,” he’s using a medieval and early modern category of knowledge that has no exact modern equivalent. If I may be allowed to fudge things a bit, we could perhaps substitute the words “mathematical proofs” for his term. In his view, consistent with his early Aristotelian education (the standard model then), “science” or genuine knowledge consisted of what could actually be known with certainty, not speculative claims or mere opinions. In his view, natural philosophy could actually achieve such certain knowledge–a view that would have been held also by Kepler, Melanchthon, and many others at the time. Only later on, after his encounter with Bellermino and the Vatican, did Galileo come somewhat to appreciate the hypothetico-deductive nature of scientific knowledge, such that absolute certainty was not a realistic goal for natural philosophy. Even then, in his heart of hearts he believed that natural philosophy ought to aim for the certainty of mathematics: readers of his final great work, The Discourses on Two New Sciences, will see him aiming at that goal often, with his mathematical idealizations of nature that enable him to make demonstrative arguments about the physical world.
Necessary demonstrations for Galileo aren’t ordinary observations. Quite the contrary. Often they contradict ordinary observations. For example, his abstract demonstration that, in the absence of friction, two bodies of unequal weight will fall evenly to Earth. He admired “those who have done such violence to their senses,” as to accept the truth of the Copernican theory–which is flatly contradicted by common sense and ordinary observations.
Yes–if science proves it by “necessary demonstrations,” then it’s a fact to which the interpretation of Scripture must conform. However–and this is a crucial “however”–Galileo did not believe this applied to many biblical claims, including the Resurrection and eternal life and the Trinity. Such things were revealed to us by Scripture and could not be known in any other way (in his opinion). Reason and observation were insufficient to give us knowledge of such things; the Bible’s purpose was to do exactly that.
But, the Bible’s purpose was not (in his opinion, and mine) to tell us true scientific facts about how nature works. I’ve already explained this above. In that limited context, then, we start with nature, not with the Bible, and we need to keep in mind the purpose of Scripture, its intended audience (the “rude and unlearned”), and the fact that its language is necessarily accommodated to that audience. So, indeed, we must prioritize scientific conclusions about nature over biblical statements about nature, which absolutely aren’t intended to explain how nature works down deep.
This is indeed why Galileo ultimately got into trouble with Rome: he was elevating the status of science from that of a mere obedient “handmaiden” to an independent source of truth that was, in its limited sphere, clearer and more reliable than the literal sense of Scripture. That was scary to many people, but in time it became the standard “concordist” model. In that model, scientific conclusions about many things (the age of the earth, the age of the universe, the structure of the universe) are fully accepted as more reliable than the literal sense of Scripture–except biological evolution, which is not seen as a reliable conclusion of science.
Incidentally, some historians believe that Galileo’s reference to the ordinary person as “rude and unlearned” implies that from time to time he had been within earshot of a rock concert. Unquestionably he preferred Giovanni Gabrielli to heavy metal, hands down. After all, his father was a major music theorist (without whom we probably don’t get Bach’s “Well Tempered Clavier”) and lutenist; one of his father’s pieces found its way into Respighi’s “Ancient Airs and Dances.”
About 18 months ago I gave a lecture, “Galileo and the Garden of Eden,” to an early modern study group at the U of MN. The video is embedded on this page: https://cla.umn.edu/early-modern/news-events/news/galileo-and-garden-eden-lecture-ted-davis. Anyone interested in Galileo’s arguments and their uses by subsequent Christian scientists and theologians is invited to drop in and listen–and raise questions here.
Recently I had someone familiar with the topic of Galileo and his house arrest explain to me that Galileo caused a lot of his own troubles. I found that to be a pretty odd way to address the general issues embraced by Galileo’s experiences.
Naturally, we can all say that “Times were different then.” But is this really a well-tempered approach? Socrates was expected to die because of what he taught his students. And Socrates would, no doubt, have to pay the same price in most Islamic nations of the medieval period - - if not even a few countries right now in 2018!
We can all look to the circumstances of the past and understand how it is that things were different. But nevertheless, we still have to come to a judgment on these matters. If we don’t, then how are we to address issues like Slavery? Do we say: “things were different then” - - and not also conclude that slavery needed to end?
In the case of Galileo, “House Arrest for maintaining a provocative tone with authorities regarding science” is really not “okay”. Sure, we know things were different then. But it was not OKAY for Galileo to be placed under house arrest for what he did.
And while the notorious Bruno wasn’t actually advancing science in the way we understand science today, his being literally burned alive for religious heresy is also not okay.
And the Vatican maintaining a list of banned books - - including scientific works - - 74 years prior to Galileo being condemned in 1633, and sustained for 380+ years, was also not okay - - and represents a rather sustained effort of “not okay-ness” that, fortunately, is no longer an ongoing mark of shame for the esteemed Roman Catholic Church.
[From 1559 to 1948, and formally abolished in 1966]
The Pauline Index [an early version of the banned book index] "… was promulgated by Pope Paul IV in 1559, which Paul F. Grendler believed marked “the turning-point for the freedom of inquiry in the Catholic world.” It was “… then replaced by what was called the Tridentine Index (because it was authorized at the Council of Trent), which relaxed aspects of the Pauline Index that had been criticized and had prevented its acceptance. The 20th and final edition appeared in 1948, and the Index was formally abolished on 14 June 1966 by Pope Paul VI.”
Footnotes:
[1] Grendler, Paul F. “Printing and censorship” in The Cambridge History of Renaissance Philosophy, Charles B. Schmitt, ed. (Cambridge University Press, 1988, ISBN 978-0-52139748-3) pp. 45–46.
[2] Lenard, M (2007). “On the Origin, Development and Demise of the Index Librorum Prohibitorum”.
Journal of Access Services. 3 (4).
[3] The Church in the Modern Age, (Volume 10) by Hubert Jedin, John Dolan, Gabriel Adriányi 1981;
ISBN 082450013X, page 168.
Thank you @TedDavis, been processing your posts, which are much appreciated. It is possible some of this may make it into my book, so your correction and calibration here is very helpful.
Perhaps, but I’m not sure Galileo was correct.
Yup, a fairly memorable passage, that undercuts @Patrick earlier claim.
But whoever is too stupid to understand astronomical science, or too weak to believe Copernicus without affecting his faith, I would advise him that, having dismissed astronomical studies and having damned whatever philosophical opinions he pleases, he mind his own business and betake himself home to scratch in his own dirt patch, abandoning this wandering about the world. He should raise his eyes (his only means of vision) to this visible heaven and with his whole heart burst forth in giving thanks and praising God the Creator. He can be sure that he worships God no less than the astronomer, to whom God has granted the more penetrating vision of the mind’s eye, and an ability and desire to celebrate his God above those things he has discovered. A short treatise of biblical exegesis in "Astronomia Nova" | Inters.org
Not exactly “civil.” Though, I still see more care in Kepler’s exegesis than Galileo’s.
I suppose this is making my point. It still seems like Galileo is making the opposite argument (to the same end) as Kepler, and I hope you can show me where I am missing it.
Galileo seems to be arguing that Scripture says the sun stood still (implying that it usually moves), but we know from clear demonstration that this is false. Geocentrism may be what Scripture seems to indicate, but we need to rework our interpretation in light of the demonstration it is false. Ironically (for those who point to him), he uses the word “concord.” He also does not appear to have to the same sensitivity to language as Kepler.
Kepler seem to be arguing that Scripture says that the sun stood still in the sky and remains entirely correct in the language of ordinary perception. Even Copernicans speak of sunrise and sunset, after all. It is not that the interpretation must change, in merely need to be correctly contextually bounded to ordinary perception. Kepler here is making a much more (in my view) grounded and gentle corrective, arguing for what had to be the original meaning of the passage, with high sensitivity to language.
So what am I missing here @TedDavis? I’ve read both Letter to the Duchess and Introduction fully through. I also admit that I’m describing their views to accentuate the difference. Reading the text, it is more subtle. That also might be because of different translators too. So I’m not 100% sure here, and could use your help. Perhaps it is a style or personality difference I am picking up on? Though it does seem like a difference in approach to Scripture. Can you help me figure that out? (maybe @rcohlers can help too)
Which will feed in nicely to the upcoming conversation on @rcohlers…
I suppose I’m not entirely comfortable with that deal. For all its flaws, I see wisdom in the Chicago Statements, which appear to draw heavily (though probably unknowingly) on Kepler. Essentially, we can’t a prior keep Bible out of the scientific domain (like NOMA), but we can make careful hermeneutical moves to make sense of science and scripture together.
Except that is not what Kepler seems to be saying. He is arguing for a more literal interpretation, that has no problem with literalism, as long as it is in the context of ordinary perception, rather than extrapolated into non-ordinary context.
You certainly might be right. Any everyone should trust your instinct over my crazy ideas here. Though I’m still seeing a gap between Galileo and Kepler’s argument on ordinary perception. In Kepler, I see a model of engaging Scripture with careful questions. In Galileo, I see him playing a science trump card. What am I missing?
@TedDavis thank you so much for engaging here and helping me make sense of this. Looking forward to ASA too, and perhaps there you’ll set me straight. Peace.
Galileo did not have the scientific high ground in his assertion that heliocentrism is correct. Here is my analysis as an astrophysicists (not as a historian, so might get some things wrong):
The orbital data that was available cannot distinguish between heliocentrism and geocentrism. This is exacerbated by Galileo’s insistence that the planetary orbits are circular instead of elliptical.
If indeed the Earth moves, then parallax from distance stars should be observable. This measurement was only made a couple of centuries after Galileo’s death. Back then, it was thought that stars are much closer than they were (Galileo computed the distance to Mizar to be 300 AU, while modern measurements give a number that is ~17000 times further). If the stars were that close, parallax should be readily observable. Galileo had no answer to this missing parallax problem.
So, imagine yourself as a scientist in Galileo’s time. You were given two theories, where
The current observation cannot distinguish between them.
One of the theories have an observational hole in them.
And ask whether Galileo’s insistence that heliocentrism is definitely the correct theory is scientific or not.
Interestingly, Galileo dismissed Kepler’s ellipses because he considered circular orbits to be perfect (shades of Aristotelian aesthetics!), and also dismissed Kepler’s correct idea that the Moon was at least partially the cause of tides. In general, Galileo frequently engaged in heated polemics against those with contrary ideas, which probably contributed significantlyto his later difficulties with the Catholic church. https://www.astro.umd.edu/~miller/teaching/honr229Xs11/lecture03.pdf
Kepler wrote to Galileo in 1597 admiring his work, and Galileo replied in kind. In 1610, Galileo wrote to solicit an endorsement for The Sidereal Messenger - slightly tricky as Kepler could not confirm his telescopic observations (he was a mathematician more than a practical man like Galileo), but he complied, with a letter he later published. This included what seems like a hint:
I can only ask Galileo insistently that he will continue his observations and as soon as possible inform us of the results. I’m looking forward to the moment when I will try Galileo’s telescope. However, I would change some things: I will increase the number of lenses with perfectly spherical surfaces on both sides. (Reply to Galileo’s request for endorsement of “The Sidereal Messenger”, April 1610).
He subsequently revised the letter and published it, with more hints at the desrirability of collaboration thus:
Such assertions about the body of the moon are made by others on the basis of mutually self-supporting evidence. Their conclusions agree with the highly illuminating observations which you report on the same subject. Consequently I have no basis for questioning the rest of your book and the four satellites of Jupiter. I should rather wish that I now had a telescope at hand, with which I might anticipate you in discovering two satellites of Mars (as the relationship seems to me to require) and six or eight satellites of Saturn, with one each perhaps for Venus and Mercury.
And later in the same:
Would you like me to express my feelings? I want your instrument for the study of lunar eclipses, in the hope that it may furnish the most extraordinary aid in improving and where necessary in recasting, the whole of my “Hipparchus” or demonstration of the sizes and distances of the three bodies, sun, moon, and earth. For the variations in the solar and lunar diameters, and the portion of the moon that is eclipsed, will be measured with precision only by the man who is equipped with your telescope and acquires skill in observing.
Therefore let Galileo take his stand by Kepler’s side. Let the former observe the moon with his face turned skyward, while the latter studies the sun by looking down at a screen (lest the lens injure his eye). Let each employ his own device, and from this partnership may there some day arise an absolutely perfect theory of the distances.
Later that year, in reponse to an unauthorised print of this reply, Kepler wrote again to Galileo, including this:
Yet if I won a lawsuit against the publisher, I would sentence him to the following punishment. He should pay for your work on a good wide convex lens, which would be a part of a sphere twelve feet in radius or its equivalent. For here at Prague I could readily find someone to make a concave lens for me. The difficulty is only in the convex lenses. For with their own equipment they accomplish little, and they pretend to despise my instructions. This, I understand, is their way of eliciting advice. I don’t have the money to build a machine at home, and I am not handy, being given
to speculation only
(Letter to Galileo 1611)
But as far as I know, Galileo never responded to any of these. And that sems to be in keeping with his jealpous guarding of his own reputation - and his own instrumentation.