On Galileo

Yesterday's post on Rick Perry's Galileo gaffe has gotten a lot of attention, much supportive, but some critical. On twitter, historians of science Rebekah Higgit and Thony Christie have helped me sort out some of the threads. I don't think this alters any of the basic results, but it's worth teasing out some of the history, both for its own sake, and for whatever relevance it may actually have to contemporary politics.

The contentious lines argued that Perry's "opening passage, like his comments on evolution, seem to forthrightly endorse the legitimacy of letting religious and political authority suppress ('outvote,' in his words) scientific results. By the time Galileo was publishing on heliocentrism, the idea was already circulating and widely accepted in scientific circles, including Jesuits. He wasn't outvoted by scientists, he was outvoted by the political and religious leadership of his country."

i-e968eda6721ecaac081c085f768900b1-GalileoHolyOffice.jpgHiggit responded first, writing: "Be careful here: Perry's right. *Geocentrism* was the scientific consensus in 1610," and linking to an excellent post by Thony Christie on why everyone didn't become a Copernican in the 16th century. I noted that I hadn't asserted a consensus, and asked if I'd overstepped by saying it was "widely accepted." Christie said I had, because "Amongst scientists heliocentric supporters were a minority till 1650 at the very earliest." Of course, something could have wide, but minority, support, but it was pointed out that "Between 1543 [when Copernicus published De revolutionibus] and 1600 [before Galileo and Kepler started publishing on these issues] there were 10 Copernicans in the world." And "On astronomical issues Galileo did not enjoy the support of the majority of astronomers. His views were respected but not accepted."

I asked if it was fair to say that Galileo lived in a period between consensuses, and Christie agreed: "In a stage between consensuses is a good description," and linked to this very helpful post on that interregnum, which notes: "As Galileo and the other early telescopic astronomers first made their discoveries at the end of the first decade of the 17th century there were not two competitors in the ring but a whole handful weighing in for the honour of explaining the mysteries of the universe."

Thony Christie wound up the discussion thus:

Despite all that Perry is still talking through his arse, The first half of the 17th C was a scientific debate in astronomy between informed parties not an opinion poll. Perry's stand on climate change in no way equates with Galileo's situation no matter which way you turn it.

To summarize, then, the grand point still holds. I suppose "wide support" may have stretched things, though by the 1630s (when Galileo was sentenced to house arrest) and 1640s (when he died), I think it's a justifiable claim, as it wasn't meant to suggest majority support, let alone consensus. When Galileo's heliocentrism was first taken up by church authorities in 1610, heliocentrism didn't have wide support, but I don't think I claimed it did. As for whether Galileo was outvoted by other astronomers or by the political and religious leadership, I feel at ease. It took time, and his views weren't instantly accepted by all, but his downfall was not because of his science, it was because he pissed off the wrong people. Certainly, in the long run he wasn't voted down by scientists, and in his own day, the story is more complicated than the Galileo gambit would imply.

Galileo's ideas had some support from Jesuit astronomers and from Cardinal Barberini (who later became Pope Urban VII). Pope Urban even urged Galileo to publish his views on heliocentrism since the two had been disputing the issue privately for years. But when he did so in his Dialogue Concerning the Two Chief World Systems, he took a few too many swipes at the Jesuits, and put the Pope's arguments in the mouth of Simplicio (Italian for "simpleton"). By then, the Pope was fending off his own political rivals, and this apparent attack (which historians seem to agree was unintended) could not be allowed to stand. So Galileo was tried for heresy and punished with house arrest in his villa.

In that instance, then, the issue was not the views of other astronomers - the claim Perry was advancing - but the political/religious leadership in Rome.

Similarly with his earlier brush with the Holy See. The gist of heliocentrism had existed publicly since 1543, when Copernicus published De revolutionibus. That document and an abstract of its argument had circulated privately for some years previously, but knowing it might cause trouble, Copernicus continued to gather data in order to refine his argument, ultimately publishing shortly before his death. Copernicus didn't offer his system as a model for how the universe was organized, either, he just wanted a more accurate and simpler system for calculating astronomical phenomena. True heliocentrism took longer, and as Christie notes, faced various competitors through that transitional period between the geocentric and heliocentric ages.

In many ways, this parallels the way modern evolutionary theory rose. Like Copernicus, Darwin sat on his major work on evolution for decades, refining and hoping to overwhelm religious opposition by dint of evidence and effort. After their publications, both went through a period of (in historian Peter Bowler's phrasing) "eclipse," ultimately rescued by mechanistic refinements. In Darwin's case, the rediscovery of Mendelian genetics fixed a gaping hole, while for Copernicus, it was Kepler's addition of elliptical orbits which allowed heliocentric models to improve markedly on the accuracy of geocentric models. After those discoveries, the respective scientific worlds were relatively quick in coalescing around the new model, with 20-30 years of battle between Darwinists and various forms of Lamarckians and saltationists in the early 20th century, and 40 years between Kepler and Galileo's work in the 1610s and the dominance of heliocentrism in the 1650s.

That period was surely extended by Galileo's persecution in the 1610s. He published Sidereus Nuncius in 1610, which challenged heliocentrism and Platonic models of the solar system in various ways, not least by reporting Venus's phases, as well as Jupiter's moons and flaws on the surface of the Moon and the Sun. By 1615, he had been denounced to the Roman Inquisition. The matter was referred to Cardinal Bellarmine, a theologian. He resolved that Copernican models could be used as mathematical abstractions, to the extent that they better predicted astronomical events, but that it went too far to interpret that success as evidence that the Sun, not the Earth, was fixed in space:

there is no danger in saying that, by assuming the Earth moves and the sun stands still, one saves all of the appearances [make accurate predictions] better than by postulating eccentrics and epicycles; and that is sufficient for the mathematician. However, it is different to want to affirm that in reality the sun is at the center of the world and only turns on itself, without moving from east to west, and the earth is in the third heaven and revolves with great speed around the sun; this is a very dangerous thing, likely not only to irritate all scholastic philosophers and theologians, but also to harm the Holy Faith by rendering Holy Scripture false.

It must be emphasized, this was hardly a scientific judgment, but a theological one. The views of scholastic philosophers and theologians are cited, but not the views of natural philosophers or mathematicians (terms that would encompass what we think of as scientists today).

Bellarmine does mention scientific evidence, but sets such a high bar that no one could have cleared it, and set that bar based on theology, not anything empirical.

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. 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 [predict accurately], and to demonstrate that in truth the sun is at the center and the earth in the heaven; for I believe the first demonstration may be available, but I have very great doubts about the second, and in case of doubt one must not abandon the Holy Scripture as interpreted by the Holy Fathers.

Again, this is not a question of being outvoted by scientists, but of holding scientific claims up to theological standards, and to absurd ones at that. Bellarmine never suggests a way to demonstrate heliocentrism, nor is it clear why the burden should be on Galileo to supply both the empirical findings and a theological justification for them.

To be clear, I grant freely that the simple story of the Galileo affair as a conflict between science and religion is too simple. Science didn't exist yet as an entity, and religion was inseparably entwined with the state, and with philosophy, and thus with what we now regard as science. Because of Thomas Aquinas's endorsement, Aristotle was known simply as The Philosopher, and the temporal power of the Catholic Church was used to enforce such philosophical standards. What we would think of as science was then included as part of philosophy, such that it was far more relevant to cite scholastic philosophers against Galileo, and far more appropriate that philosophers and theologians sit in judgment over his work.

Still, Galileo rightly chafed at these restrictions, and the 1616 ruling of a jury of theologians who declared heliocentrism "foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture" further constrained him. He got assurances from various people that he could continue publishing as long as he treated heliocentrism either as a mere calculating tool, or only presented it as one of various options, without advocating for it. By 1633, he had crossed too many friends, and crossed those lines, and was punished. It is no small quibble to note that his house arrest in 1633 was less about heliocentrism than about his violation of that previous ruling.

This is cold comfort in general, and no comfort at all for Perry. After all, the only prominent votes on Galileo's work were panels of theologians organized by the state to protect the orthodoxy. As historian Thomas Mayer told the New York Times: "If Perry means to say that at some point some body of scientists said Galileo was wrong, that didn't happen." Individual scientists certainly disputed with Galileo, but Mayer explains, "His notions about science were not that far out there. There were a lot of other scientists, especially in Rome, who more or less agreed with his scientific observations."

Mayer's take is a bit stronger than what Higgitt and Christie told me, but it's not hard to align the three historians' views with one another, nor with what I said yesterday. And again, none give Perry any comfort.

Which brings us to Martin Cothran. Regular readers will recall him as a writer for the Kentucky affiliate of hate group Focus on the Family, a blogger for the creationist Discovery Institute, and a frequent defender of Holocaust deniers, antisemites, the Confederacy, and any anti-woman or anti-gay policy he can find. Now he's rushing to the defense not only of Perry, but of the Roman Inquisition which prosecuted Galileo and sought to suppress heliocentrism.

He argues, implausibly: "Not only did Perry not get it wrong, he got it more right that Rosenau."

To justify that, he first insists that when Perry said Galileo was "outvoted," "it isn't clear" Perry was "necessarily saying that the majority rules in science." What other plausible interpretation is there? Perry was asked to name any scientist who backs his own view, and the only scientist he named was Galileo, who he claims was outvoted!

Then Cothran repeats a whiggish tale of the Catholic Church and heliocentrism, in which Galileo's trials revolved around "the epistemological status of the theory--whether it was a legitimate hypothesis or a proven fact. At the time of the controversy, it was not a proven fact and there were a number of unanswered problems with it--a fact acknowledged by both scientists (such as they were) and Church officials."

I've linked to Cardinal Bellarmine's letter on heliocentrism, and quoted the relevant bits above. I defy anyone to read that and tell me that Galileo's books were censored and he was sentenced to a lifetime of house arrest because of a dispute about scientific terminology. Yes, Bellarmine offers the possibility that heliocentrism might be acceptable, but only if it clears theological hurdles. And the objections offered by the Qualifiers in 1616, and the Inquisition in 1633 are principally theological as well.

Furthermore, Cothran's discussion of the relationship between theory, fact, and hypothesis is simply wrong, not to mention anachronistic. A theory is not an idea that hovers somewhere between a fact and a hypothesis. Theories are overarching explanatory frameworks. They integrate facts, hypotheses, laws, predictions, and tests. They give facts and hypotheses meaning, and help generate new hypotheses, which generate new research, which helps produce newly discovered facts. The question, properly stated, would not have been whether the heliocentric theory was a fact or a hypothesis, but whether it was a good enough theory. Thony Christie's post linked above gives a good sense of why people in the early 17th century would have found heliocentrism an imperfect theory, and what sort of evidence helped move them past those objections. I don't know what language an early 17th century Italian would have used for any of these distinctions, but I'm fairly sure that the language Cothran is using isn't right. Cothran's phrasing here is the sort of cod-Baconism that abounds in evangelical subcultures, a perversion of a long-abandoned scientific philosophy.

Finally, Cothran's account of the case is contradicted by Pope John Paul II, who wrote:

like most of his adversaries, Galileo made no distinction between the scientific approach to natural phenomena and a reflection on nature, of the philosophical order, which that approach generally calls for. That is why he rejected the suggestion made to him to present the Copernican system as a hypothesis, inasmuch as it had not been confirmed by irrefutable proof. Such therefore, was an exigency of the experimental method of which he was the inspired founder....

the new science, with its methods and the freedom of research which they implied, obliged theologians to examine their own criteria of scriptural interpretation. Most of them did not know how to do so. Galileo, a sincere believer, showed himself to be more perceptive in this regard than the theologians who opposed him. "If Scripture cannot err", he wrote to Benedetto Castelli, "certain of its interpreters and commentators can and do so in many ways."

Cothran then abandons history altogether, pretending that Galileo was convicted of heresy and imprisoned because he was "a reckless and arrogant controversialist" who "demanded that others accept his theories before he had adequately documented them," and then "demanded that his theological views be acknowledged as legitimate despite his demonstrable lack of expertise in the field." "In fact," Cothran says, "he was so reckless and arrogant, he managed even to alienate his friends." Even if this is true, it was not what Galileo was charged and convicted of, and if anything it undermines whatever point Rick Perry might have been making. Indeed, if this were a just basis for a life sentence to house arrest, Cothran and Rick Perry would be among the many, many people who would have cause to live in fear.

Finally, Cothran makes this absurd set of claims:

In reality most of the scientists of the time opposed [heliocentrism], since most of the university scholars working in what was then natural philosophy ... believed in a version of Aristotelian teaching that precluded Copernicanism. Church officials of the time largely accepted Copernicus' theory as better fitting the data than the Ptolemaic theory, but were content to let the scholars duke it out. And a number of high Church officials not only didn't oppose Galileo's heliocentrism, but encouraged his writings on the issue, include a future pope.

I think I addressed that above. Church theologians were the ones who dedicated themselves to Aristotle above the evidence. Galileo's books built on solid observational science to argue that not only was heliocentric math easier, it better described the shape of the solar system. That realization, which a growing number of astronomers shared, was publicly rejected by the church on explicitly theological grounds, though certainly some within the church were willing to discuss the issue. Church officials accepted the Copernican system as a mathematical trick, but explicitly rejected the notion that the solar system really was heliocentric. In the end, that same "future pope" who encouraged Galileo to write on the issue was the pope who threw him to the Inquisition. Cothran implies that Urban urged Galileo to write because he agreed with him, but this is false. Simplicio, the geocentrist in Dialogue is making Urban's arguments, and it is partly because Galileo put Urban's words in such a bad light that Galileo was punished.

Finally, when the Pope is ready to concede that the Church erred in the Galileo case, it's probably a bit late to be charging to defend that piece of history. Pope John Paul II noted: "The error of the theologians of the time, when they maintained the centrality of the earth, was to think that our understanding of the physical world's structure was, in some way, imposed by the literal sense of Sacred Scripture." This, of course, is the same error Cothran makes when he seeks to advance creationist policies, but that's a topic for another day.

There are certainly exaggerations of the Galileo affair out there. He wasn't tortured, wasn't burned at the stake, and his house arrest was pleasant enough to give him time to pursue major research and writing project, and to pursue medical care. He could surely have been treated worse, but this hardly means he was treated well, let alone that, as Cothran claims, "the Church was defending was proper scientific methodology." It's hard to imagine that heliocentrism was anything but held back by the Church's prosecution of Galileo, its editing of Copernicus's books, its absolute censoring of Copernican books by Foscarini and others, and its execution of Giordano Bruno (who advocated an even more extreme version of heliocentrism, but whose heresy charges had more to do with his belief in many worlds, each with their own Adam and Eve, their own Eden, their own Messiah, etc.). There were plenty of legitimate reasons why people might have delayed joining the heliocentric bandwagon, but the possibility of censorship or execution can hardly be omitted.


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What's wrong with this comment by JP2? It sounds like he's saying literal interpretations such as geocentrism -- and by extension, creationism -- are not the way to go. Isn't that what a leader should be saying?

I think you are being unfair toRoberto Bellarmino and misinterpreting his letter. Yes he was a theologian but he also had a solid grounding in astronomy like any Jesuit and had even lectured on the subject in his youth.

He does not specify what was necessary to confirm the heliocentric hypothesis because in 1615 when he wrote his letter it was well known amongst astronomers what would confirm the movement of the earth. In fact it was the failure of Galileo and other supporters of heliocentricity to provide that proof that left the majority of astronomers still doubting the hypothesis.

In 1616 Galileo himself always avoided claiming the truth of the heliocentric hypothesis because he knew that if he did so he would be on a very sticky wicket scientifically. Probably as a scientist his biggest mistake in life was in believing that his theory of the tides, which to put it mildly was a complete balls up, actually proved the movement of the earth.

[picking myself up off floor after laughter-generated fall]

Okay, now back to reality . . .

The LATimes has a good editorial today. The money quote:

"At this point, the empirical evidence for warming, like the evidence for a heliocentric solar system or for evolution, is so strong that denial reflects a faith-based approach to public policy."

By Cheryl Shepher… (not verified) on 10 Sep 2011 #permalink

Parenthetically, Galileo's theory of the tides may be seen as less than a complete balls-up, in that it originated in a theory of the seiche, which in fact accounts for a great deal of the behavior of tides in the real world. This was, AFAIK, the first time anyone applied this idea, or even thought about a seiche -- or made any attempt to explain actual tides. (Any simple model of tides is, of course, so inaccurate in much of the world as to be useless in predicting anything.) This is not an unworthy work in science, particularly when his specific application of the idea to the problem of the tides in the Adriatic Sea was entirely right.

Galileo's theory of the dynamics that drive the tides was, of course, wrong.

Back to Perry. I have yet to see anyone notice that any virtual "vote" you take among the duly qualified experts of the time must exclude the best of them, the Jesuit astronomers. Why? Because, from 1616 on, they were strictly forbidden to "hold or defend" heliocentrism, just as all Catholics were. And they damn well knew it. Which makes any of their publicly expressed opinions of no value in assessing the scientific status of heliocentrism at the time.

BTW, 1616 appears to be when Tycho's theory caught on big-time, having previously been scorned (as being, in effect, not even wrong) not only by Galileo and Kepler but by Clavius, the dean of the Jesuit astronomers until his death in 1612.

Another matter that a person would never guess from these recent debates: by that time it was hardly possible to accept the standard Aristotle-Ptolemy model, which was contradicted by too many observations that everyone could replicate. That's why the Jesuits and others wanted to grab some theory that would at least, as they say, preserve the appearances.

By Porlock Junior (not verified) on 18 Sep 2011 #permalink