Galileo Gambit

Galileo Gambit July 27, 2013

Open Parachute has a great post about the Galileo gambit or Galileo fallacy, the notion that having one's ideas opposed somehow demonstrates that they are correct.

Here is a takeaway quote:

The real lesson from Galileo is not to oppose the “establishment” or current scientific consensus – but to rely on evidence. It was this argument of his, which today most of us accept and see as almost self-evident, that describes Galileo’s real contribution to the progress of science.His argument for the heliocentric solar system, and against a geocentric solar system, was really an argument of evidence against dogma, prevailing philosophy and the Church’s use of scripture.

And here is another:

Of course, none of what I have said means that new ideas in science are never in the minority. obviously they often are – and must be fought for. But new ideas don’t win credibility by using the Galileo gambit, by arguing that just because they oppose the scientific consensus they must be right. They win credibility because their proponents gather the evidence that supports them, and evidence which conflicts with the prevailing ideas.A minority viewpoint can and does win credibility because its proponents provide evidential support. The Galileo gambit is for losers.

Click through to read more. The point relates directly to recent discussions of science standards in Kentucky, but also to how even Christians who accept that the Bible is not a science textbook can respond dismissively to science. See also Tyler Francke's blog post about the propaganda film Dispelled, the removal of the Loch Ness Monster from one anti-science “educational” resource, and Ray Comfort's continued effort to make Christianity look foolish, this time by saying that there is more evidence for God than for the sun. For some of the evidence for evolution, take a look at Dennis Vennema's series on the genome as ancient text – and see also another BioLogos article on why sometimes we need to deal with other issues before a presentation of evidence will persuade someone. And finally, see Formerly Fundie on real vs. fake persecution claims.


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  • arcseconds

    The business with Galileo is more complex than most people realise. At the time there were strong scientific reasons to reject geocentricism (e.g. lack of observed stellar parallax; if the earth is moving so fast why don’t things not attached to the surface fly off it). These objections were eventually answered, but not until later, and Galileo’s attempts (e.g. circular inertia) weren’t correct.

    There were certainly high-ranking people in the Church who were sympathetic to heliocentric models. Cardinal Bellarmine is a good example, who was open to re-interpret scripture if heliocentricism could be proved, although while he saw advantages to the heliocentricism he didn’t think it had been proven (correctly, given the information of the time, in my opinion).

    Galileo wasn’t initially instructed to steer clear of heliocentricism altogether, but rather to refrain from advancing it as the truth (as opposed to a hypothesis). He was also encouraged to give geocentricism a fair go, which he did so in an ironic fashion by putting it into the mouth of Simplicio in his Dialogue concerning the Two Chief World Systems. Also in Simplicio’s mouth, a sceptical criticism of Galileo’s (incorrect) account of the tides advanced by Pope Urban.

    So while of course the Church has no right to give orders about what can be written, much of what they wanted from Galileo was actually pretty reasonable.

    Instead, he decided to be an arse about it.

    • Yes you could say that Galileo got in trouble for insulting the Pope. You could also say that the Pope was a man who, when insulted, used the inquisition to threaten Galileo with torture unless he recanted his scientific findings, then placed him in house arrest for the rest of his life. Who was more of an arse?

      • arcseconds

        Yes, we could say either of those things I suppose, but neither is anything more than a crude caricature of the least interesting point I made in my post, so I’m not sure why we would.

        I know it’s all very exciting to reduce history down to good guys and bad guys and cheer for the good guys and boo for the bad guys, but by doing so we mythologize it.

        • I agree that that we shouldn’t mythologize it. Which is why I responded to your reductive comment that Galileo “decided to be an arse about it”.

          Talk about “crude caricatures”!

      • Ignorantia Nescia

        It is an interesting question, but we must take care not to get bogged down in whiggery when passing moral judgment’s about history. However, at the time censorship was really standard fare, see this post by a historian of science: I do not know to what degree the Pope’s own arsity is a factor.

        It is safe to say that such threats with torture and censorship should be considered blatantly unethical today and rightfully so, but we must accept that our views had zero causative power in the seventeenth century. As for who was the bigger arse, I think the answer is not as clear-cut as you might want it to be. Galileo was brilliant at making enemies and that was not achieved by gentleness, sociability and debate ethics.

        • arcseconds

          It does seem that the ‘affair’ was as much about Galileo defying direct instructions as anything he actually said.

          There was also the fact that he, a layman, had taken upon himself to interpret the Bible in favour of heliocentrism, a touchy subject given the Reformation (a point made in the post you link to).

          It seems to me that a more interesting question than ‘who is the biggest arse’ is ‘who had more autonomy in this situation’, and the answer seems to me to be Galileo. He could have chosen to express himself in a concillitory rather than pugnacious tone in the same sense that any of us has a choice in how we express ourselves, and it would have been better if he had done so. Urban, on the other hand, was a ruler in a somewhat precarious position (he was massively unpopular amongst both the public and the Cardinals, some of whom were planning to assassinate him). It would take an unusual person indeed to tolerate Galileo’s defiance under such circumstances.

          I think our host’s treatment of cdbren makes for an
          interesting comparison.

          cdbren had been given several warnings about his stubborn sophistry and disrespectful behaviour in support of YEC, and so McGrath eventually banned him, in part for our ‘protection’ (so we don’t waste any more time in fruitless, roundabout arguments).

          (cdbren thinks he can interpret science better than scientists, so he’s also refusing to accept the appropriate authority here).

          I guess we could say the Pope took (and his successors seem to continue to take) the whole world as their blog.

          • Ignorantia Nescia

            Thanks, I didn’t know about Urban’s predicament at the time. It would indeed odd for him to let Galileo off lightly in those circumstances. Your point about the ball being in Galileo’s court is fair. His confrontational behaviour was typical (often backed by the Accademia dei Lincei), but also unstrategical.

          • David Evans

            I agree, “who was the greater arse” is seldom a good question to ask of history.

            A better question might be “is it a good idea for a church to have authority over the expression of ideas?”

          • Perhaps we should have refrained from calling anyone an “arse” in the first place.

            Whatever one thinks of Galileo’s social ability, he was brilliant scientist, and promoted a rational view of the relation between science and scripture:

            “For that reason it appears that nothing physical which sense ­experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called in question (much less condemned) upon the testimony of biblical passages which may have some different meaning beneath their words.”


    • Ignorantia Nescia

      To add a few details to the description in arcseconds’s superb post, first Galileo’s circular inertia was also inconsistent with his argument that the rotation of the Earth causes the tides. It is also worth adding that Galileo depended on mediaeval natural philosopher, which is carefully argued in James Hannam’s book God’s Philosophers (UK)/The Genesis of Science (US).

      Perrott’s take-away quote is quite off the mark here: “His argument for the heliocentric solar system, and against a geocentric solar system, was really an argument of evidence against dogma, prevailing philosophy and the Church’s use of scripture.” As arcseconds pointed out, evidence was quite against Galileo’s views. The lack of an observed stellar parallax was a strong argument against heliocentrism at the time and for that reason it was a minority view. The Tychonic model (the sun and the moon rotating around the completely stationary Earth and the other planets rotating around the sun) and the semi-Tychonic model (now with an Earth having axial rotation) were more accepted for the reason it did not require a stellar parallax, though ‘interestingly’ it was omitted by Galileo in The Dialogue, where he only put the increasingly obsolete Aristotelian worldview against his Copernican version of heliocentrism.

      Yes, “Copernican version” because Kepler’s heliocentrism, which is the correct picture in classical mechanics, was quite distinct from Copernicanism. It got rid of circular orbits and epicycles, unlike Copernicus’s model. So there was actually a large variety of theories at the time: the Copernican, the Aristotelian, the Tychonic, the semi-Tychonic and the Keplerian model. The reason the Keplerian model became accepted was not because empirical evidence weighed in its favour, but due to the acceptance of Netwon’s theory of gravitation, which provided a theoretical framework in which Kepler’s laws could be derived. A stellar parallax was only observed for the first time in the nineteenth century. Given that, it is hard to call Galileo’s “argument for the heliocentric solar system, and against a geocentric solar system” “really an argument of evidence” against whatever.

      Here is a much more detailed account of the affair by Tim O’Neill:

      • arcseconds

        I still find it fascinating that it was actually Newton’s theory (and not a piece of ‘evidence’), decades later, that provided the solution for the heliocentric vs. geocentric debate. And only a dynamical theory could provide such an answer.

        That speaks against any simple-minded empiricism, where facts are just there for the observing.

        And the answer, of course, was they were both wrong.

        • Ignorantia Nescia

          Yes, it is ironic that some people uphold it as some triumph of evidence while the eventual justification was not empirical.

          About simple-minded empiricism, you might find Hume’s description of the validation of the heliocentric model intriguing. He (as Philo in the Dialogues) gets the reason why this worldview was accepted completely wrong, because he only accepts the empirical:

          “Yes! cried PHILO, interrupting him, we have other earths. Is not the moon another earth, which we see to turn round its centre? Is not Venus another earth, where we observe the same phenomenon? Are not the revolutions of the sun also a confirmation, from analogy, of the same theory? All the planets, are they not earths, which revolve about the sun? Are not the satellites moons, which move round Jupiter and Saturn, and along with these primary planets round the sun? These analogies and resemblances, with others which I have not mentioned, are the sole proofs of the COPERNICAN system; and to you it belongs to consider, whether you have any analogies of the same kind to support your theory.”

    • “At the time there were strong scientific reasons to reject geocentricism (e.g. lack of observed stellar parallax; if the earth is moving so fast why don’t things not attached to the surface fly off it). These objections were eventually answered, but not until later, and Galileo’s attempts (e.g. circular inertia) weren’t correct.”

      Actually, Galileo was quite correct in his answer to stellar parallax, and his illustration of a ship’s cabin to demonstrate that bodies in motion together share inertia was the correct answer to the problem of objects flying off the surface of the earth. To say that his notion of “circular inertia” was incorrect is about as useful as saying that Newton’s laws of gravity were incorrect. To be precise, Newton’s laws were incomplete, but they were necessary precursors to Einstein’s Relativity. just as Galileo’s circular inertia was an incomplete but necessary precursor to Newton’s rectilinear inertia. And Galileo’s contributions didn’t end (or begin) with the Dialogue. As Stephen Hawking has noted, Galileo’s Discourse on Two New Sciences anticipated Newton’s laws of motion.

      • arcseconds

        Ah, good, you’ve finally moved on from the last sentence of my comment.

        Galileo, of course, recognised that no observable stellar parallax and things not flying off the face of the earth were problems for heliocentrism, so he made two assumptions to cover them.

        One was that the distance of the stars was so great that no parallax could be observed. Actually, he didn’t originate this suggestion: Copernicus had suggested it decades earlier.

        The other was that planetary bodies naturally move in circles.

        These were both speculations, albeit both clever and plausible given the science of the day (although Galileo can’t get too much credit for the first, as it wasn’t his idea), with no real evidence to support either.

        They were hypotheses necessary to save the phenomena. In terms of their relationship to empirical evidence, they were no more than that.

        The first one happens to be correct. The second one is dead wrong.

        It’s not even approximately correct. Bodies just don’t move in circles or anything like circles on their own, they need (in Newtonian terms) a force to make them do that.

        So the comparison to Newton’s theory is inapt. At the time, Newton’s laws of motion had a fair amount of experimental proof behind them (and Newton did further experiments to support them) and his universal gravitation was deduced with great rigour from those laws and various phenomena. So they had far greater empirical justification than the stellar parallax or circular inertia.

        In terms of how we understand things today, Newton’s laws of motion and universal gravitation are correct as an approximation at low velocities and weak fields.

        Now, the circular inertia was a bold idea, and it turns out that there was a useful concept in there: the idea of inertia and natural motions apart from rest (although Galileo wasn’t the first to propose such notions). Galileo’s work in this area did influence Newton, so it was indeed a precursor to the ‘correct’ theory, but I don’t think there’s anything necessary about that. I can’t see why circular inertia had to be proposed before rectilinear inertia could be discovered — it seems to me rectilinear inertia could have easily have come first.

        There’s nothing wrong about any of this. Indeed, it’s good for scientists to propose bold-but-plausible ideas, especially in times when there’s enough data with enough structure to suggest theories, but no-one’s gotten one that works yet. But we need to be clear about what the relationship to the known phenomena was at the time.

        At the time, there weren’t any very good reasons to believe Galileo’s heliocentric theory above any of the other theories of the solar system. So for his work on the solar system, why do we exalt him, rather than Tycho or Wittich? It seems to me it gives a distorted and unhelpful view of the history of science if we always focus on the winners, especially if they won due to chance more than anything else.

        The single most important idea Galileo had, in my view, was his discovery that talking about motion or rest makes no sense without a reference point — in other words, his discovery of relativity.

        • arcseconds

          Actually, I suppose I’ll have to amend my statement about bodies traveling in circles. The motions of the planets are their ‘natural’ inertial motions according to general relativity, where there is no ‘gravitational force’, just distortions of spacetime. However, I’m still not inclined to give much credit to Galileo for happening upon a description that looks a bit like the 20th century one: to the extent that it’s correct, it’s a lucky guess (and the role the primary body plays is still critical).

          • Ah, Galileo did cite a role for the primary body in his descriptions – the earth, the sun, and Jupiter in his examples.

            You make Galileo sound like an armchair theorist making stabs in the dark and “lucky guesses”. He crafted telescopes that (for the first time in history) made possible the observations of Jovian moons, Venusian phases, sunspots, and clusters of newly-sighted stars in the Milky Way.

            Of course, when Galileo usually referenced the inertia of bodies, he was speaking of bodies on earth, such as the projectiles he worked with in his treatise “Two New Sciences”.

            As I’ve said, that you’re “not inclined to give much credit to Galileo”, really doesn’t make much difference when the world’s greatest physicists are so inclined.

          • arcseconds

            We were discussing specifically the cases of the stellar parallax and circular inertia, and in both of those cases, given the observable phenomena of the time, the proposals were speculative. Again, the problem here seems to be not so much that you disagree with me, but that you’d like to see more eulogic verses about how great Galileo’s telescopes were.

            (They’re not entirely irrelevant, of course, but they’re not so relevant that they absolutely must be mentioned in a handful of paragraphs on geocentricity and heliocentricity.)

            I’m not inclined to give Galileo much credit in the specific case of getting circular inertia right by modern standards. You’re the only person I’ve ever read who’s inclined to defend him on circular inertia, but even you don’t credit him with amazingly intuiting the modern position.

            I’ve already credited the circular inertia as a bold and influential idea.

          • You’ll find that most science historians give Galileo a great deal of credit for advancing scientific understandings about inertia. He never used the term “circular inertia”; it’s a term used by current historians to point out just one aspect of inertia that he didn’t have quite right (no one did at the time).

            In any case, (correct me if I’m wrong) I thought we were discussing Galileo’s case for a heliocentric model, for which his astronomical observations were not only relevant, but critical. As far as the lack of parallax goes, using it as an argument against heliocentrism was equally speculative, since noone had the capability of measuring distances to the stars. Copernicus and Galileo simply pointed out that parallax doesn’t work as an objection to heliocentrism because it makes assumptions about unknown stellar distance. At best, lack of parallax was neutral to the question of heliocentrism vs geocentrism.

            I don’t really feel the need to eulogize Galileo any more than history already does. But I’m not sure what your point is?

          • arcseconds

            Well, McGrath’s post was about using Galileo as a paradigmantic example of someone who was opposed and persecuted for his ideas, but it turns out he was right all along.

            My main point is that the ‘Galileo Affair’ was not a clear-cut example of that. Galileo didn’t have a watertight case for heliocentrism. The Church wasn’t opposed to heliocentrism on principle, they just wanted Galileo to advance it as a hypothesis rather than truth, and to give geocentrism a fair go. Regardless of whether they had the right to demand this, it was a reasonable enough position to take on the matter. By the standards of the time, this was actually quite an enlightened approach. And he was punished more for disobeying orders (and insulting the Pope) than he was for giving arguments for heliocentrism.

            Plus, the whole thing was rife with politics, of which Galileo was by no means independent. He had powerful supporters in the Church hierarchy (which included Pope Urban himself at one point) and probably thought that was sufficient to protect him. I even recall reading somewhere that it was rival scientists who pushed the issue into the limelight in the first place.

            The whole thing is a complicated, messy business which can’t really serve as a sterling example of anything much, except maybe how real life seldom lives up to mythology.

            This isn’t terribly different from my first comment on this post, so I’m not sure if that clarifies anything for you, but I’m not sure how to make it any clearer. The point wasn’t to denigrate Galileo as a scientist.

          • I don’t think that “McGrath’s post was about using Galileo as a paradigmantic example of someone who was opposed and persecuted for his ideas, but it turns out he was right all along.” Maybe this is why your original comment confused me, and made me think that you were simply denigrating Galileo’s contributions.

            The main point of the post is about those who use the Galileo affair to promote the idea that bucking the establishment or having the minority opinion somehow makes one right or correct. This is what Rational Wiki, as cited by Open Parachute, is calling the “Galileo Gambit” or the “Galileo Fallacy”, and this central point is not at all an attempt mythologize the Galileo affair – if anything it is the opposite.

            In fact, that is the opening statement of the Open Parachute post that James is referencing: “It’s one mark of the significance of Galileo to scientific progress that many myths about him exist even today.”

            Open Parachute discusses the same Galilean errors that you do, but his real point lands in a quotation from Galileo’s Letter to the Grand Duchess Christina:

            ““I think that in disputes about natural phenomena one must begin not with the authority of scriptural passages, but with sense experiences and necessary demonstrations. . . . and so it seems that a natural phenomenon which is placed before our eyes by sense 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.”

            This is the point of the post. Not that Galileo had an “airtight” case for heliocentrism, but that he argued for scientific disputes to be decided by evidence rather than by adherence to biblical interpretations.

          • arcseconds

            McGrath’s post is about people ‘who use the Galileo affair to promote the idea that bucking the establishment or having the minority opinion makes one somehow right or correct’, yes, we agree on that.

            Why do they use it? Well, I think it’s because it’s commonly accepted as a paradigmatic example of someone who was persecuted for their ideas, but who was right all along!

            (I’m supposing you don’t disagree with that?)

            So McGrath’s post is indeed about using the Galileo affair as a paradigmatic example of someone who was persecuted for their ideas and who was right all along. I didn’t say McGrath was using it as such an example.

            McGrath and OpenParachute maintain that it’s silly to compare yourself with Galileo, basically because to do so you have to have the evidence on your side, which is exactly what is in question when the scientific community ‘marginalizes’ you. I certainly agree with that.

            However, neither McGrath nor OpenParachute actually challenge the myth (that Galileo was persecuted for being right) itself. The fact that the affair was not actually a clear-cut example of someone having compelling evidence but being persecuted for it is another reason why they shouldn’t use Galileo as such an example.

            ( OpenParachute actually perpetuates the myth by saying the issue was evidence. )

          • I don’t see how OpenParachute perpetuates the myth that Galileo was persecuted for being right by saying the issue was evidence. OpenParachute makes the point that evidence was important to Galileo, not that it was important to those who were persecuting him.

            The heresy trial was not about evidence but about authority, which is exactly why the points about evidence in Galileo’s letter to the Duchess Christina (also suppressed by the Inquisition along with his heliocentric writings) are important.

            I don’t believe that Galileo’s only intent was to defy authority (however much of an “arse” he might have been). He clearly believed that evidence such as the clear support that the phases of Venus provide for heliocentrism were compelling enough to rethink the distance of the stars. Consider how well Newtonian physics describes most astronomical observations – but one measurement of starlight bending around the eclipse of the sun was enough to propel physicists around the world to rethink everything Newton gave us in terms of General Relativity.

            You are right that Galileo was defying instructions, and certainly put the Pope in an awkward position. I don’t quite see why this gave Galileo more “autonomy”; whatever “autonomy” he might have had, he was soon to lose! He might have treated both cosmological models with equal support in the Dialogue, as instructed, but he clearly didn’t think they warranted equal support.

            More importantly, his writings on the preeminence of evidence were a step away from a system in which scientific writings must follow Ecclesiastic commands.

          • arcseconds

            You say that the heresy trial was not about evidence, but about authority. I think that glosses over the politics of the situation, and it also glosses over the part the evidence did play in the affair (see below). But if we’re going to reduce the whole thing down to a slogan, I’m much happier with ‘authority’ rather than ‘evidence’.

            Note that this is not what OpenParachute is saying. They’re saying it’s about the evidence, as you say in the opening of the post I’m replying to.

            As far as the evidence goes, the Church (or at least, the high-ranking members of the Church that interacted with Galileo in the events leading up to his trial, notably Pope Urban and Cardinal Bellarmine) had a better attitude to the evidence than Galileo did. The evidence wasn’t conclusive, and they weren’t going to go against what the Bible suggested unless it was — but there were distinct signs that they were prepared to do this (Bellarmine stated this very openly).

            Yes, Galileo thought he had proved heliocentrism beyond reasonable doubt. But he was wrong about that — that’s not just my opinion, but the opinion of his peers (geocentric models remained in vogue (alongside heliocentric ones) until Newton) and the opinion of contemporary historians and philosophers of science.

            It’s not uncommon for scientists to have more enthusiasm for their theories than the evidence really suggests.

            By ‘autonomy’, I mean that of all the people involved, the person who could most have avoided the whole affair was Galileo himself, by merely toning down his rhetoric and being more diplomatic. To expect that of him is only to attribute the kind of autonomy we attribute to any author: that the tone and the presentation of their writing is within their control, and they are answerable for it.

            To expect anything differently of the Pope, we would have to attribute an ability to rise above the situation which is extremely rare in people who seek positions of authority, particularly when their position is precarious, and their authority has been challenged. Along with other things that surely couldn’t have been the case, such as sharing our values of free enquiry, speech and opinion.

          • arcseconds

            As far as the parallax goes, given the information at the time it does support geocentrism more than heliocentrism, in my opinion.

            Geocentrism is compatible with the stars being any distance away from the Earth and displaying no parallax. Heliocentrism, on the other hand, is committed to the assumption that the stars are an extremely long way away. So heliocentrism has to make an additional assumption over geocentrism, which already lowers its probability.

            Someone (I can’t remember who. Kepler, maybe? ) calculated that the stars would have to be many times the distance of Saturn away to not have an observable annual parallax. This was regarded as improbable by many people at the time, and I’m inclined to agree with this assessment. All other bodies are either Saturn or closer than Saturn, so the information available points to a universe of the order of the size of the orbit of Saturn. Positing a very much larger universe than this is going against the direct information you have of the size of the universe.

            That’s not to say that the parallax argument demolishes heliocentrism. I think the rational position at this point in time (when nothing was known about why the planets move as they do) would be scepticism leaning towards geocentrism, but with heliocentrism as a viable option, worth pursuing.

            (Galileo’s discovery of the phases of Venus kind of disproves the Aristotelean / Ptolemaic system, but it doesn’t decide among Tychonian, heliocentric, or Capellan systems. The discovery of moons of Jupiter certainly shows that bodies can orbit things other than the Earth, but again this supplies evidence for Tychonian and Capellan models as much as it does for the heliocentric one. )

          • What point are you trying to make, arcseconds?

          • arcseconds

            That at the time, the lack of observed parallax supported geocentrism. I said this in the opening sentence of the comment you are replying to.

            I noted this in my initial comment, and my comment beginning ‘as far as the parallax goes’ was in reply to your comment saying the parallax doesn’t support either side. I think it supported geocentrism given the information available at the time, and I was stating my reasons for thinking that.

            I can’t really see anything especially opaque about my remark, so I’m not sure why my point is eluding you. Again, I feel I’m repeating myself, and I don’t know how to make this any clearer to you. Maybe you’re continuing to attribute an agenda to me I don’t have?

          • Yes, I got your point about parallax (that was clear enough). Galileo did answer the objection, of course, by proposing the great distance of the stars – an idea supported by his telescopic observations of further unseen individual stars within the Milky Way, suggesting a vaster universe than had been considered before. He also had corroborating evidence, including his observations of the phases of Venus.

            I agree with you that the dispute between cosmological models was not resolved at the time, but I don’t think that undercuts the point of the original post. Galileo’s writings about the precedence of evidence over ecclesiastical authority in his letter to the Grand Duchess Christina was circulated and became quite influential before it’s suppression by the Inquisition.

            And the suppression of his writings speaks to the dogmatic authority of the church at the time.

        • Well, your last sentence is on the money. Einstein himself credits Galileo with this basic principle of relativity.

          That’s right. Copernicus had already offered the solution to parallax. Funny, you didn’t mention that when you stated that “lack of observed stellar parallax” was an objection to heliocentricism that was “eventually answered, but not until later”.

          You mischaracterize and oversimplify what historians’ later called Galileo’s notion of circular inertia. He wasn’t simply stating that bodies “move in circles”. He was describing inertia, in a way that was correct for earth-bound bodies moving in relation to a spherical planet, just as Newton’s laws are correct for bodies moving at a fraction of the speed of light. In other words, Galileo was describing inertia combined with gravity. Did he see the entire picture? Of course not. And Newton never dreamed that the gravity he described as a force was actually caused by the curvature of space-time.

          You are right that Galileo’s propositions were often built upon the work of earlier scientists. The same is true of Newton.

          You are free to think that Galileo’s work on inertia, planetary motion, falling bodies and parabolic forces had no influence on Isaac Newton’s laws of motions. You are also free to believe that Galileo was a completely “speculative” scientist, notwithstanding the unprecedented telescopic observations he made of the Jovian moons, the phases of Venus, the craters of the moon, and the revolution of sunspots, as well as his documented experimentation with projectiles.

          I tend to side with the physicists, such as Einstein and Hawking, who disagree with you.

          • arcseconds

            Well, apparently you’re free to insinuate all sorts of things I didn’t actually do, too. I may have the freedom to do those things, but I didn’t exercise it.

            I never said Galileo had no influence on Newton. I never said he was a completely speculative scientist, either. Where are you getting this stuff from?

            And you’ve started to indulge in irrelevant nick-picking as though they were actual criticisms. What does it matter I never mentioned Copernicus? It doesn’t materially change anything I did write, and I don’t think I have to cover the entire history of every idea in astronomy in my already rather long posts.

            As far as I can work out, we don’t actually disagree about any of the facts (except maybe how on the money Galileo’s inertia was, but even there the difference seems to more be you think it’s cooler than I do). The problem seems to be that I’m not cheerleading sufficiently enthusiastically for Captain Galileo and Team Science, which has got you all upset, which is leading you to overgeneralize from specific things I’ve said (some of Galileo’s ideas were speculative, sometimes Galileo behaved like an arse) to an inaccurate picture of how I’m characterising Galileo (Galileo was merely speculative and always an arse).

            This isn’t like what I’m used to from you. Normally you’re calm, rational, and fair. I suggest you go and have a cup of tea, and think about something else for a couple of days.

          • How funny – I was thinking of suggesting a cup of tea for you. You seemed to take great exception to my “Who was more of an arse” comment, which was no more than a playful retort to your “he decided to be an arse about it” comment.

            Actually, I’d agree that Galileo was being a “bit of an arse” in the Dialogue. A very clever arse, humorously bucking his instructions not to promote heliocentrism over geocentrism.

            So maybe I’ve overstated your denigration of Galileo. What point are you trying to make?

          • Ignorantia Nescia

            “I tend to side with the physicists, such as Einstein and Hawking, who disagree with you.”

            What is the relevance of their views? Neither of them was/is a historian of science and judging from the history chapters in Hawking’s The Grand Design, it was a good career choice that he did not become one.

          • Hi Ignorantia

            As it turns out, in this conversation, arcseconds doesn’t believe that we disagree very much anyway (I’ve overstated our differences), so the point is moot.

            Are you a professor of science history? If so, what history do you think Hawking get wrong in the The Grand Design?

        • PorlockJunior

          Too much of that long comment is just simply wrong to be dealt with. (Somebody is wrong on the Internet!)

          An egregious example: Galileo explained away the parallax problem by assuming that the stars are far away? For FSM’s sake man, people were PROVING that heliocentrism is wrong because no stellar parallax, and he argues that that does *not* prove it, and so he’s just *assuming* the opposite?

          No, he is refuting a claimed proof. Logic, you know.

          He’s also invoking elementary geometry, which his adversaries seemed (*) content to ignore. And BTW the matter that the stars might be too far away is not the invention or discovery of Copernicus. Try Archimedes. The Sand Reckoner. A true sceintist there, who attempted to compute the magnitude required for this effect, and then applied it in his estimate of how much sand it would take to fill the universe. The sort of thing that Galileo did, which was not popular because *mathematics*!

          (*) Seemed, I say, because the parallax argument was not quite so weak as his modern friends’ version is. It was still wrong, because their estimate of the stars’ apparent size was wrong; but not hopelessly bad. Just not anything like a conclusive argument. BTW, you do know that G proposed a couple of methods by which one could try to observe the parallax? It’s not an issue he tried to duck, or anything. But no one could imagine then just how big the universe really is.

          “The other was that planetary bodies naturally move in circles.”

          That’s Galileo’s assumption? More like the conventional idea of the “natural motion” of that type of body (in contrast to the elements that naturally move to the center of the world/universe).

          Or is the point that everyone else knew that the planets moved that way becuase of the crystalline spheres? But Tycho, as his many fans like to mention, debunked those — incompatible with his scheme as with heliocentrism.

          Actually, as you say, exalting Galileo for his work on planetary mechanics would be not a very good idea; the brilliant work there was Kepler’s. Galileo made a number of observations that showed that the old system could not be true, and made no secret about them. (BTW, he was not the only one to consider Tycho’s attempt at a fix to be useless, in effect a kludge; two others were Kepler and Clavius.)

          The reason he comes up, and the reason he appeared in the actual blog posting before it got derailed into side issues and personalities is the fight with the church (duh), not the perfection of his arguments.

          But equating his system to *any* of the others runs into some famous problems, like phases of Venus, and blemishes on the Sun and Moon (the perfection of heavenly bodies being an intrinsic part of the beloved older systems), and the actual motion of sunspots in a pattern extraordinarily hard to reproduce with spots on a stationary Sun.

          Trying to wrap up: The whole idea that Galileo relied on an idea of “circular inertia” is a long matter of controversy, far too large for the space in this margin at this time of night, but it’s worthvmentioning that it’s not a simple matter of established fact.

          But we can agree on his insight into relativity of motion. It’s striking how Einstein moved away from the dynamics of Newton right back into a kinematic theory with, you might say, a non-Euclidean twist.

          • arcseconds

            Too much of that long comment is just simply wrong to be dealt with. (Somebody is wrong on the Internet!)

            The feeling is entirely mutual, I assure you 🙂

            An egregious example: Galileo explained away the parallax problem by assuming that the stars are far away? For FSM’s sake man, people were PROVING that heliocentrism is wrong because no stellar parallax, and he argues that that does *not* prove it, and so he’s just *assuming* the opposite?

            I’m not really sure of what your point is here. It would make some sense if Galileo was claiming only that heliocentrism was a conceptual possibility, and that its opponents didn’t have a completely convincing argument that it wasn’t. But he wasn’t claiming that, he was making a far more stronger claim for heliocentricity than that. For that he needed an explanation of why there was no observed parallax, and this is the one he gave.

            So, yes, he needed to make this assumption. Which is not an assumption that affects geocentrism one way or another, which means that so far as this point goes, heliocentrism is the weaker theory.

            There were attempts made to measure the parallax. They all failed until the 1800s. This is not a point that supports Galileo.

            I’ll look in to the Sand Reckoner business. I’ll confess I don’t know much about Archimedes. It’s hardly an important point, though — either way, the great distance idea is not Galileo’s.

            I must admit I misphrased this:

            “The other was that planetary bodies naturally move in circles.”

            I shouldn’t have said ‘planetary’, and I see now I was a bit confused at that point, and said some irrelevant things to beau_quilter. Thanks for pointing this out.

            I stated this better a couple of comments before.

            He proposed circular inertia to avoid the objection that if the Earth is moving so fast, why don’t things fly off it? So it’s not so much he assumed that the planets’ natural motion was circular (none of the models we’re discussing had an explanation for their motion), but rather he assumed that stuff on the surface of planets also naturally moved in circles. Again, he needed some argument against this point, this is the one he made, and again it’s an assumption that geocentrism doesn’t need to make.

            I don’t object to him making this assumption: it was an interesting idea, and his work on inertia contributed to Newton’s work. But it was nevertheless an assumption he made to support heliocentrism, that he had very little evidence for, and (in this case) wasn’t really correct.

            You seem to be aware that the competitor to heliocentrism at this time wasn’t the old ptolemaic/aristotlean model, but rather the Tychonian system and various Capellan models. Could you explain why you think the phases of Venus are a problem for them?

          • arcseconds

            Again, a bit like beau_quilter, except moreso, you sound like there’s some huge disagreement here. You start off with a dramatic statement about how wrong I am.

            But I’m left in confusion about where we actually differ.

  • I still think the best assessment of this episode in scientific history is Albert Einstein’s forward to the “Dialogue Concerning the Two Chief World Systems.”

    “The leitmotif which I recognize in Galileo’s work is the passionate fight against any kind of dogma based on authority. Only experience and careful reflection are accepted by him as criteria of truth. Nowadays it is hard for us to grasp how sinister and revolutionary such an attitude appeared at Galileo’s time, when merely to doubt the truth of opinions which had no basis but authority was considered a capital crime and punished accordingly.”

    The current popular apologetic argues that Galileo didn’t have the evidence to back up heliocentrism at the time, and picks on his errors concerning tides and “circular inertia” (which was not so much an error as an incomplete predecessor to Newtonian rectilinear inertia). In any case, these were hardly the only evidences he offered for heliocentrism. His astronomical observations of sunspots, the moon, and the Jovian system all supported his view of the solar system, and he derived the correct answer to the problem of parallax in citing the remoteness of the stars.

    The humor of Galileo’s Dialogue wasn’t lost on Einstein:

    “Apart from its revolutionary factual content the Dialogue represents a down-right roguish attempt to comply with this order in appearance and yet in fact to disregard it. Unfortunately, it turned out that the Holy Inquisition was unable to appreciate adequately such subtle humor.”

    We can credit Isaac Newton for describing the forces of gravity and inertia that make sense of planetary motions, but Newton’s starting point was Galileo’s work on the parabolic motions of projectiles.

    Newton and Galileo both give enormous credit to Galileo’s work, and they were well aware of every error and insight he made. The current apologetic penchant for minimizing Galileo’s contributions to science is selective in it’s history, biased in its conclusions, and hardly worth consideration.

    • Ignorantia Nescia

      Einstein was a brilliant physicist, but not a historian of science. How probable is it that he has given the best assessment? As for its contents, it’s full of not completely untrue but overall overstated claims. However you look at it, Galileo was a devout Roman Catholic and did not oppose dogma in religion. As for possible claims “dogma in science”, the heliocentrism controversy was an exception in the relation between the Roman Catholic Church and “science” (an anachronistic term) and the degree of ecclesial interference is often exaggerated, as had already been addressed by several commenters.

      • What is your beef with Albert Einstein? What has he “overstated”?

        Are you saying that the Inquisition did not impose “dogma based on authority”?

        I’m sorry, Ignorantia (great handle btw), but after reading a few anonymous blog commenters spouting their takes on science history, the reply that Albert Einstein’s and Stephen Hawking’s views are not relevant because they are not “science historians”, just makes me laugh a little.

        • arcseconds

          History of science is a specialist discipline in its own right. Like any historical discipline, primary research requires pouring over primary source material, as well as staying up to date with other experts in the field, and being aware of historical methodology, etc.

          As far as I know, neither Einstein nor Hawking devoted much time to this, so their work in this area should not be preferred to that of actual experts, and, to put it bluntly, is more likely to reflect the mythology of the science community than it is a nuanced historical understanding.

          This sort of consideration is more or less the same issue that McGrath has with mythicists.

          • The problem with your mythicist analogy is that James’ opinion on the historicity of Jesus actually carries some authority; he’s a biblical historian.

            But who are you and Ignorantia? Are you expert science historians?

            Now if you had been citing expert historians to support your assessment of Galileo from the beginning – then maybe you might have a point about my references to Einstein and Hawking. As it stands, all I see here are two anonymous Internet handles claiming that Albert Einstein and Stephen Hawking don’t have the expertise to disagree with you (whoever you are) – which is frankly silly.

            At any rate, I don’t see anything in their writing that would disagree with you (much more a consensus of historians), if all that you’re saying is that it was a complex affair, Galileo’s case for heliocentrism wasn’t “airtight”, and politics were involved.

            I think you may be missing the central point of the post and the Open Parachute post that James is referencing.

    • PorlockJunior

      “Newton and Galileo both give enormous credit to Galileo’s work”

      Where are the French? Someone ought to show up with a complaint about ignoring Descartes. Then a postmodernist could carry us further afield by attacking Newton’s dishonesty in not using calculus in the Principia. (Not making this up.)

      BTW, beau, apologies for having jumped in to say mostly what you had said aleady and more clearly.