460. Trial and Error: Galileo and the Inquisition
The philosophical issues at the heart of the notorious condemnation of Galileo and Copernican astronomy.
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Themes:
• M.A. Finocchiaro (trans.), The Galileo Affair: a Documentary History (Berkeley: 1989).
• M.A. Finocchiaro (trans.), The Essential Galileo (Indianapolis: 2008).
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• R.J. Blackwell, Behind the Scenes at Galileo’s Trial (Notre Dame: 2006).
• R.E. Butts and J.C. Pitt (eds), New Perspectives on Galileo (Dordrecht: 1978).
• H.D. Rutkin, “Galileo Astrologer: Astrology and Mathematical Practice in the Late Sixteenth and Early Seventeenth Centuries,” Galilaeana 2 (2005), 107-43.
• S. Drake, Galileo at Work: His Scientific Biography (Chicago: 1978).
• S. Drake, Galileo: a Very Short Introduction (Oxford: 2001).
• R. Feldhay, Galileo and the Church: Political Inquisition or Critical Dialogue? (Cambridge: 1995).
• M.A. Finocchiaro, Galileo and the Art of Reasoning: Rhetorical Foundations of Logic and Scientific Method (Dordrecht: 1980).
• M.A. Finocchiaro (trans.), The Galileo Affair: A Documentary History (Berkeley: 1989).
• M.A. Finocchiaro, Defending Copernicus and Galileo: Critical Reasoning in the Two Affairs (Dordrecht: 2010).
• M.A. Finocchiaro (ed.), The Routledge Guidebook to Galileo’s Dialogue (London: 2014).
• M.A. Finocchiaro, On Trial for Reason: Science, Religion, and Culture in the Galileo Affair (Oxford: 2019).
• H. Gatti, “Giordano Bruno’s Ash Wednesday Supper and Galileo’s Dialogue of the Two Major Systems,” Bruniana e Campanelliana 3 (1997), 283-300.
• O. Gingerich, “Galileo, the Impact of the Telescope, and the Birth of Modern Astronomy,” Proceedings of the American Philosophical Society 155 (2011), 134-41.
• J. Heilbron, Galileo (Oxford: 2010).
• N. Jardine, “Galileo’s Road to Truth and the Demonstrative Regress,” Studies in the History and Philosophy of Science 7 (1976), 277-318.
• P. Machamer (ed.), The Cambridge Companion to Galileo (Cambridge: 1998).
• T.F. Mayer, The Roman Inquisition: Trying Galileo (Philadelphia: 2015).
• M. Piccolino and N.J. Wade, “Galileo’s Eye: a New Vision of the Senses in the Work of Galileo Galilei,” Perception 37 (2008), 1312-40.
• J. Renn (ed.), Galileo in Context (Cambridge: 2002).
• M. Sharratt, Galilei: Decisive Innovator (Cambridge: 1999).
• W.R. Shea, Galileo’s Intellectual Revolution (New York: 1977).
• W.R. Shea, “Galileo and the Church,” in C. Lindberg and R.L. Numbers (eds), God and Nature: Historical Essays on the Encounter between Christianity and Science (Berkeley: 1987), 114-35.
• W.R. Shea and M. Artigas, Galileo in Rome: the Rise and Fall of a Troublesome Genius (Oxford: 2003).
• R.S. Westfall, Essays on the Trial of Galileo (Notre Dame: 1989).
Comments
Galileo
Good episode. It is, historically, a remarkably complex case. Ultimately it comes back to Pope Urban VIII. The argument of Pope Urban VIII (Simplicio) had to be included. There was no way Galileo could get around it; and there is no way that Pope Urban VIII could be satisfied in doing so short of Galileo abandoning his real beliefs. Galileo was caught between the rock and the hard place, and no amount of finesse could save him though he believed it could.
Modern scientific method
I don't think your description of the modern scientific method you were using to compare against Galileo is entirely accurate. Coming up with a hypothesis that you later falsify with evidence is certainly a part of science, but it's not all of science by any means. You can for instance draw conclusions from new data without going through a pre existing hypothesis.
In reply to Modern scientific method by Joshua Hillerup
Scientific method
That's definitely right, nonetheless we philosophers and historians of science use the term of art "scientific method" to refer not to everything that scientists do, but to a specific methodology that is often traced back to Francis Bacon, and has this hypothesis-test structure. We'll see more about this when we get to Bacon and other 17th century philosophers of science!
In reply to Scientific method by Peter Adamson
Ah, ok. It sometimes comes…
Ah, ok. It sometimes comes up as criticism of scientists if something they do doesn't fall under that particular method, and it can get pretty infuriating at times.
backward and ignorant
"routinely considered to be backward and ignorant"
Hmm, that's a rather broad generalization. I'd accept "routinely considered to be wrong." But, to consider a phrenologist, for example, or a proponent of phlogiston theory to be "backward and ignorant" is the sort of attitude I'd expect you, of all people, to consider, if not "backward and ignorant," then at least "wrong." So I think you are making a sweeping criticism of unspecified thinkers, something I criticize as not up to your usual standard. If you had specific individuals in mind, then I'm sure you'd examine their views with sympathy and nuance, in historical context, as you always do, not least in this episode (which was excellent, as usual).
In reply to backward and ignorant by Scott
Backward and ignorant
Oh I'm surprised you got that out of the opening of the episode: this was one of those classic "this is how people all too often think about the situation but in fact it is much more complicated" openings. So I certainly didn't mean to be endorsing the judgment that outdated scientific theories were backward and ignorant, I would have thought this was clear from the context.
Theory of the tides.
Galileo's theory of the tides was even more wrong than you indicate; it was totally disproved by the empirical evidence. His theory would have produced one tide a day, always at the same time. In reality, of course, there are two tides a day that travel round the clock by a given interval per day, in sync with the phases of the moon. Instead of rejecting the well established theory of the link between the tides and the phases of the moon, because it cause wasn't known; tables of the phases of the moon and tide tables were even published together in nautical almanacs. A real scientists should seek to find that cause.
In reply to Theory of the tides. by Thony Christie
Tides
Yikes, that's pretty damning! Didn't Galileo try to answer this kind of objection by arguing that the overall effect of the tides he described is then modified by local conditions?
In reply to Tides by Peter Adamson
Yes, it's called arm waving!
Yes, it's called arm waving!
Tides
When it was pointed out to Galileo that there were two tides a day in the Mediterranean, (a sea he lived next to nearly all of his life and it had to be pointed out!) he did indeed try to explain it away by the shape of the sea. It’s a known philosophical method known as as hand waving.
In reply to Tides by Thony Christie
Tides
With emphasis on the "waving" in this case!
Physics Critique
Hi Peter -
While I have not looked into Galileo's tidal theory like the previous commenter, you say in the episode that Galileo was wrong about the tides because "the water of the oceans is simply carried along with the rest of the earth. " This is an inaccurate statement, as the surface of the earth is not actually an inertial reference frame - Galilean invariance does not apply. In fact, a very precise description of the oceans from our reference frame really does need the centripetal and Coriolis components of the apparent force included, even if the presence of the tidal effect is not dependent on these terms. This is consistent with Galileo's rotating water bowl comparison, he must have expected apparent forces like this to show up somewhere. If only he could have seen an aerial picture of a hurricane!
P.S. I can't believe I'm almost caught up after years of listening. This podcast has been a source of much joy and I hope my wife is not too sick of hearing about it...
In reply to Physics Critique by Brandon Freudenstein
Galileo on the tides
Oh thanks, that’s very helpful - and well timed as I am just about to submit the final manuscript of the book version. So how would you phrase what Galileo got wrong here, then?
In reply to Galileo on the tides by Peter Adamson
Galileo and the tides
I have not looked into Galileo's writing directly, but trying to dig into this a bit, it sounds like Galileo's theory is that the accelerations experienced on the surface of the earth causes the water to slosh back and forth. My comment above was just referencing the rotation of the Earth, but his specific theory depends on the combined rotation and revolution around the sun to induce this sloshing. The far side of the Earth from the sun is moving faster than the near side of the Earth given these two components of its motion, so the water should be induced to move relative to the Earth's surface.
As the other commenter pointed out, this theory on its own suggests one high tide a day and therefore is not supported by empirical evidence. To me the charitable interpretation is that Galileo just did not have the physical theory or mathematical machinery to see that gravitational forces are the correct explanation for the tides. He knew that we live in an accelerating frame of reference and that this could induce motion as in the bowl of water. He also saw that the tides were a periodic unexplained motion, and so he assumed these had to be related. He then tried his best to explain the details.
The introduction to P. Palmieri, "Re-examining Galileo's Theory of Tides", Arch. Hist. Exact Sci. 53 (1998) seems convincing to me, and makes the point near the end that to prove that the kinematics he was considering do not influence the tides requires Newtonian physics to work out.
Hopefully this is helpful.
In reply to Galileo on the tides by Peter Adamson
Clarification
To clarify, I believe to show that the rotation of the Earth does not lead to oscillating tidal forces just requires Newtonian vector mechanics, since the acceleration points to the center of the Earth and has no tangential component. The Coriolis effect I mentioned would not point in the right direction either, I am not sure if Galileo knew about this effect.
The paper I linked then mentions that the effect of the revolution of the earth around the sun only doesn't contribute an annual surface-tangent force because of the actual form of Newtonian gravity. So Galileo did not need to know about gravity to see why his theory of daily tides did not work, he just needed a properly Newtonian formulation of circular motion.
In reply to Galileo on the tides by Peter Adamson
More Galileo Thoughts
Apologies for all of the comments, but after chewing on this issue your original description is closer to the truth than I gave it credit. Galileo specifically claimed that whether or not the movement of a point on the surface of the earth aligned with or moved against the Earth’s orbital motion was the cause of the water sloshing. This explanation would seem to suggest that even linear motion of a rotating earth would cause sloshing. This then can be disproved by Galilean relativity - add to the hold of his imaginary ship a rotating globe with an ant on it. That ant can figure out he’s rotating with a local experiment (centripetal and coriolis forces) but he cannot tell that he’s on a moving ship. If the ship begins to turn, the ant should be able to tell it’s turning with a local experiment, but it would not be due to forces in the direction of the ship’s tangent motion, which seems to be what Galileo had in mind with the orbiting and rotating earth.
I still want to give Galileo more credit, since that last point about the ship turning really needs an idea of vectors to get right and is not just a straightforward inconsistency in his theory. Thanks for your patience and good luck with finalizing the book.
Tides caused by gravity
"Galileo just did not have the physical theory or mathematical machinery to see that gravitational forces are the correct explanation for the tides."
The strong correlation between the phases of the moon and the tides had been well documented since antiquity. It was well known to mariners, who used it whilst planning voyages. Already in the 16th century nautical almanacs had the tables for the phases of the moon and the tide tables printed opposite each other. Johannes Kepler, who made the first attempts to define a force of attraction between the Sun and the planets had already hypothesised that forces emanating from the Moon were the cause of the tides. Galileo highhandedly dismissed this, ridiculing Kepler for believing in occult rubbish.
If Galileo was half the scientist people claim him to have been, he should have searched for a scientific explanation of the correlation between the phases of the moon and the tides not simply ridiculed it and dismissed it out of hand.
Time and Tide wait for no man
A brief note: not only would Galileo's theory of the tides mean that there only be one tide a day, it was also always take place at the same. However, as is very easy to observe the time of the tides moves around the clock with the time of the moon phases. Apparently, irrelevant according to Galileo.
In reply to Time and Tide wait for no man by Thony Christie
Apparently I’m a Galileo Apologist
Thony - Everything you’ve said here is a reasonable point. I would argue though that this is a bit of a question of scientific method. Sometimes a scientist can be convinced of a theory on some kind of rational grounds and assume the observations are misleading. A Copernican had to think this way when parallax was not observed after all. In fact, in the present day, particle physicists and astrophysicists definitely follow theories that aren’t cleanly supported by observation with the hope of making progress. Science is messier than making observations and then trying to explain them. But yes, it does still seem like a major blunder on his part, I was not aware of that historical context.
Galileo’s biggest problem…
Galileo’s biggest problem was that he was obsessed with the idea that he would be the man who proved the truth of Copernicus’ heliocentric hypothesis. You have to remember that in the first half of the 17th century nobody had succeeded in detecting stellar parallax, let alone stellar aberration, which nobody even knew existed, also there existed absolutely no empirical evidence of diurnal rotation.
Galileo’s obsession led him to make a series of major scientific blunders. His theory of the tides was the biggest. He had convinced himself that it was proof of diurnal rotation and simply ignored all of the empirical evidence that refuted it. He even originally wanted to title the Dialogo, The Theory of the Tides, but the Church censor, aware that Galileo regarded his theory as proof of heliocentricity blocked it.
He steadfastly ignored all the very solid, empirical evidence that comets were supralunar, arguing instead that they were a sublunar optical phenomenon. This was because Tycho thought that comets orbited the Sun and considered this support for his geoheliocentric theory.
Even worse he rejected/ignored Kepler’s three laws of planetary motion, although they were solidly empirical. He insisted that the planetary orbits were circular not elliptical. He completely ignored Kepler’s third law, which was by far and away the most convincing evidence available at the time for heliocentricity.
There is a popular myth that the Dialogo played a major role in the debate on the correct system of the world in the 17th century. It didn’t , because it was so wrong on so many major scientific points it was largely ignored. Its fundamental premise was even wrong. In 1630, The Two Chief World Systems were not, as Galileo claimed, Ptolemaic geocentricity and Copernican heliocentricity, but rather Tychonic geoheliocentricity, either with or without diurnal rotation, and Keplerian heliocentricity.
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