Sunday, January 2, 2011

Hume (and Popper) should take experience more seriously

It is truly remarkable that Hume (and before him al-Ghazali) was able to convince so many that there was something profoundly and systematically wrong (or, at least, seriously problematic) with our knowledge of causation, for there is surely nothing we have more intimate, varied and continuous experience of than cause-and-effect. It pervades our existence, from acts of breathing to the most elaborate projects.

How does Hume do so? By the same means al-Ghazali does. By putting the threshold of reason-to-believe very high and by putting the strength of the evidence of causation very low, both the experiential and what might be called the “metaphysical” evidence.

Regarding reason-to-believe, both Hume and al-Ghazali require proof in the sense of deductive validity. That is, they deny we can infer from cases to generalities, they deny the power of probabilistic reasoning. That all observed swans are white demonstrably does not prove that all swans are white: witness the black swans of Australia. All fine, but Hume and al-Ghazali go further, they claim that all observed swans have been white gives no reason to believe that the next observed swan will be white. For if one accepts that there are reasons to believe which are not proof, but nevertheless rational bases for belief, then Hume and al-Ghazali’s argument fails.

This is the key premise on which the entire argument sits. But, in order to make their case more plausible, both Hume and al-Ghazali recast our experience of causation into passive observance. That all we are doing is observing coincidental occurrence of cause and effect.

But that is not even remotely a full description of our experience of causation – or, indeed, our experience of experience. Experience is primarily not passive, but active. We actively – indeed interactively – experience pattern, structure and causation. Our prime experience of causation is not observing, but doing. We act, and by acting build up great experience of causation, of what does or does not happen when we do various acts. We are “inside” causation, and experience it thus. This is rather more than passive observance of coincidental cause and effect. It is only by making us think of causation as something “out there” – as something of removed, passive observation – that Hume and al-Ghazali make the characterisation of causation as mere coincidental occurrence remotely plausible and so seem as not having sufficient proof to constitute knowledge.

In his response to al-Ghazali’s argument, ibn Rushd (“Averroes”, known to medieval Scholastics as The Commentator, just as Aristotle was The Philosopher) appealed – alas, in a somewhat roundabout way – to the rationality of our belief in, and the depth of our experience of, causation when he stated that:
To deny the existence of efficient causes which are observed in sensible things is sophistry, and he who defends this doctrine either denies with his tongue what is present in his mind or is carried away by a sophistical doubt which occurs to him concerning this question. For he who denies this can no longer acknowledge that every act must have an agent. The question whether these causes by themselves are sufficient to perform the acts which proceed from them, or need an external cause for the perfection of their act, whether separate or not, is not self-evident and requires much investigation and research. And if the theologians had doubts about the efficient causes which are perceived to cause each other, because there are also effects whose cause is not perceived, this is illogical. Those things whose causes are not perceived are still unknown and must be investigated, precisely because their causes are not perceived; and since everything whose causes are not perceived is still unknown by nature and must be investigated, it follows necessarily that what is not unknown has causes which are perceived. ‘ The man who reasons like the theologians does not distinguish between what is self-evident and what is unknown, z and everything Ghazali says in this passage is sophistical.
Ibn Rushd then continues on to re-state the Aristotelian analysis of causes.

Hume and al-Ghazali are both correct to say we lack deductive proof of causation. As it is never certain that we have perceived and understood every aspect of some event, we never have more than probabilistic reasoning available to us about specific causal sequences. (So the notion that a “disproving” observation partakes of some deductive power that a “confirming” one does not is false: my old teacher David Stove used to make this point, but it took me years to fully understand what he was getting at.) Yet probabilistic reasoning can still be good reasoning, well up to the task of providing a rational basis for belief (and our systematic understanding of probabilistic reasoning has advanced quite a lot since Ibn Rushd’s day). Hume and al-Ghazali are wrong to insist that only deductive proof will do.
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While I do not find Ibn Rushd’s restatement of the Aristotelian analysis of causation in his response to al-Ghazali a satisfactory one, he is correct to take a metaphysical, which is to say a “structural” turn, for Hume and al-Ghazali’s “flattening” of experience is intimately connected to the way they discount considerations of pattern and structure. Our understanding of causation is very much built up on the basis of pattern and structure: that, for example, you can do things with a fork that you cannot do with a bat, and vice versa.

Both Hume and al-Ghazali are reacting against Aristotelian Forms, deemed to be direct apprehensible by the human mind from which causation can be deduced from our knowledge of said defining forms. But, in the way of human thought, their reaction turned into over-reaction. The belittling of the role of pattern and structure went rather too far. Hume was, for example, quite wrong to claim all knowledge of the world comes from mere experience, treated as a mass of sense-impressions, because without pattern and structure there is no basis for connecting one experience with another. We come into the world primed to identify pattern and structure: we have to be, to be able to learn, to be able to connect one experience to another. In the words of a early childhood educator, babies:
… apply limited Action Schemes to everything they come across, which is part of learning about the world. The earliest action schemes are things like grab and suck. Babies are born knowing how to do this—or at least they can do it within hours of being born. Later there is grasp & shake, which is why we give babies rattles. There's also banging, dumping (around 9 months) and turning things over to see the other side. As babies develop they get to combine these basic action schemes into more complicated patterns. So younger babies are kind of looking at the world of objects as: is this something I bang, something I shake or something I ignore? Babies & toddlers put everything in their mouths too, just like animals do. Touch it, to feel its texture, grasp and shake and turn it over, taste it. Watch a gorilla do the same thing to an unknown item the next time you're at the zoo.
Anyone who has to deal with a complex and crowded intersection for the first time will testify how different that confusing experience is to later experiences of the same intersection when one becomes familiar with its patterns and structures. Pattern and structure is basic to, and pervades, both our experience and our learning from experience, for without pattern and structure there could be no learning to speak of at all. (Nor, for that matter, any existing things at all.)

Which is not to say this priming to perceive pattern and structure is itself definitive. As a brain scientist Gary Marcus says:
The initial organization of the brain does not rely that much on experience … Nature provides a first draft, which experience then revises … ‘Built-in” does not mean unmalleable; it means organised in advance of experience” (Gary Marcus, 2004).
The priming is malleable and interactive with experience. We are not compelled to wander off into Kant’s world of phenomena and unknowable things-in-themselves noumena.

What is even more surprising about the intellectual success of scepticism about our knowledge of causation is that no one actually believes we have no understanding of causation: indeed, all of us continue to act on the basis of our built-up understanding causation based on our experience of (and inferences from) pattern and structure. (Which is then expanded by information transferred to us by language from others.) Hume’s monetary economics, for example, is all about generalised causation.

Al-Ghazali’s success is marginally less surprising than Hume’s, however, since al-Ghazali achieved extra plausibility by appealing to God: his take on causation becomes another manifestation of the submission to God that is the essence of Islam.

Aristotle was not wrong to be so concerned with pattern and structure: it is necessary for things to exist, including for thought to happen, and for any learning to be possible at all, for one experience to have any implication or connection to another. Since pattern and structure are necessary for things to exist, the universe can therefore be described using mathematics, the science of pattern and structure. The trouble was being too Platonic about pattern and structure: to put too much confidence in ideas, in the human capacity to directly categorise accurately and definitively.

But we need to be wary of the opposite problem, of being too dismissive to human perception and reason. To be sure, that mathematics has the “gold standard” of deductive proof available to it is a seductive example. But our logical and cognitive apparatus is not so impoverished that only deductive proof is good enough. This cannot be so, since so little is available to us to connect on the basis of deductive reason from what is known with certainty. We live in a world of uncertainty and so of probabilities.

And of reasoning perception based on a capacity to categorise which is far from perfect and definitive but demonstrably good enough to get by. And good enough due to reasons beyond mere happenstance. That something is not certain is not a reason not to believe it. Mere possibility is certainly not a superior reason to believe than experience. Indeed, it is not even as good a reason to believe.

Which is why the cool rationality of Hume’s scepticism about our knowledge of causation is, in fact, deeply irrational since it elevates mere possibility (which is what uncertainty is) as more defining of experience than experience itself, in the sense that mere possibility trumps inferring from experience.

Hence Hume, and those whose philosophy descends from him, such as that of Karl Popper, should take experience, including of pattern and structure, as a basis for inference more seriously in their philosophy. Indeed, as seriously as they did every waking moment of their lives.

So, Ibn Rushd has a point, the reasoning is sophistical, as long as we grant that the first deceived were the reasoners themselves.

16 comments:

  1. Back in the day I wrote a uni paper on The Incoherence of the Philosophers. Surprisingly for the sometime Islamophobe that I was, I concluded that this time Islam had been given a bum rap. After reading - all in English translation - Al-Ghazali, Ibn Sina (Avicenna), and Ibn Rushd's (Averroes) The Incoherence of the Incoherence, I concluded that any stagnation that might have occurred in Science in the Islamic world could not logically be connected to Al-Ghazali. In fact his writings are full of praise for what he called the “exact sciences”.

    He just rejected the notion that the exact sciences – mathematics, medicine, astronomy – had anything to say on the higher knowledge of religion; in this instance he was following Aristotle’s hierarchy of knowledge, with metaphysics at the top followed by mathematics, and then natural philosophy (physics). But as you note, he was no fan of Aristotle’s peculiar metaphysics. al-Ghazali was scornful, seeing Aristotle as some ante-deluvian rube, whom the Muslims should not deign to stoop to. He rubbished Avicenna’s “proof” of God’s existence, as it consisted entirely of – erroneous metaphysical claims, not once resorting the falsafa’s toolbox.


    In non religious areas, however, al-Ghazali happily acknowledges that human’s can discern causation. Al-Ghazali’s attack on the Islamic followers of Greek natural philosophy (falsafa) – in particular Al Kinda, Al Farida, and Ibn Sina (Avicenna) – was largely because they – in his opinion – were not Aristotelian enough. He in fact says that Greek national philosophy is the best way to understand the physical/natural world. But the tools of natural philosophy – mathematics, logic, and demonstration – were useless as tools to understand other types of knowledge, namely religion.

    On Mathematics:

    A grievous crime indeed against religion has been committed by the man who imagines that Islam is defended by the denial of the mathematical sciences, seeing that there is nothing in revealed truth opposed to these sciences by way of either negation or affirmation, and nothing in these sciences opposed to the truth of religion.

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  2. In fact he chastised the faithful who deny scientific proofs, which do not contradict religious (metaphysical) principles.

    On Astronomy:

    “ In the second place, there are those things in which the philosopher believe, and which do not come into conflict with any religious principle. And, therefore, disagreement with the philosophers with respect to those things is not a necessary condition for the faith in all the prophets and the apostles (May God bless them all).

    An example is their theory that the lunar eclipse occurs when the light of the moon disappears as a consequence of the interposition of the Earth between the Moon and the Sun. For the moon derives its light from the Sun, and the Earth is a round body surrounded by Heaven on all sides. Therefore, when the Moon falls under the shadow of the Earth, the light of the Sun is cut off from it. Another example is their theory that the solar eclipse means the interposition of the body of the Moon between the Sun and the observer, which occurs when the Sun and Moon are stationed at the intersection of their nodes at the same degree.

    We are not interested in refuting such theories either; for the refutation will serve no purpose. He who thinks that it is his religious duty to disbelieve such things is really unjust to his religion, and weakens its cause. For these things have been established by astronomical and mathematical evidence which leaves no room for doubt.

    If you tell a man, who has studied these things – so that he has sifted all the data relating to them, and is, therefore, in a position to forecast when a lunar or solar eclipse will take place: whether it is total or partial; and how long it will last – that these things are contrary to religion, your assertion will shake his faith in religion, not in these things. Greater harm is done to religion by an immethodical helper than by an enemy whose actions, however hostile, are yet regular.

    For as the proverb goes, a wise enemy is better than an ignorant friend”.

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  3. The resemblance to the Galileo affair is stunning. Both the Inquisition and al-Ghazali rejected any scientific theory that presumed natural philosophy could inform metaphysics (religion). As religion and scripture are not material/physical in nature, neither Mathematics (including astronomy) nor Physics has anything to say on them. Remember, Galileo’s crime was not asserting heliocentrism, per se. He only got into trouble when he wrote a letter to the Grand Duchess Christina claiming that in his Sunspot Letter he rejects the biblical story about Joshua stopping the sun, and replace it with his own allegorical meaning.

    Like al-Ghazali’s “incoherent philosophers”, Galileo has moved beyond the natural philosopher’s expertise by passing judgment on the higher – metaphysical truths of scripture. He arrogantly ignored Lord Cardinal Bellamine’s warning that he could use his heliocentric model suppositionally - as Copernicus’ initially purported to – but Galileo was forbidden to say its truth was greater than the biblical Joshua story. The whole Galileo Affair was so much more nuanced that is commonly understood.

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  4. Aaaaaarrrrgghhhh...It didn't publish the first hald of the first post



    Back in the day I wrote a uni paper on The Incoherence of the Philosophers. Surprisingly for the sometime Islamophobe that I was, I concluded that this time Islam had been given a bum rap. After reading - all in English translation - Al-Ghazali, Ibn Sina (Avicenna), and Ibn Rushd's (Averroes) The Incoherence of the Incoherence, I concluded that any stagnation that might have occurred in Science in the Islamic world could not logically be connected to Al-Ghazali. In fact his writings are full of praise for what he called the “exact sciences”.

    He just rejected the notion that the exact sciences – mathematics, medicine, astronomy – had anything to say on the higher knowledge of religion; in this instance he was following Aristotle’s hierarchy of knowledge, with metaphysics at the top followed by mathematics, and then natural philosophy (physics). But as you note, he was no fan of Aristotle’s peculiar metaphysics. al-Ghazali was scornful, seeing Aristotle as some ante-deluvian rube, whom the Muslims should not deign to stoop to. He rubbished Avicenna’s “proof” of God’s existence, as it consisted entirely of – erroneous metaphysical claims, not once resorting the falsafa’s toolbox.


    In non religious areas, however, al-Ghazali happily acknowledges that human’s can discern causation. Al-Ghazali’s attack on the Islamic followers of Greek natural philosophy (falsafa) – in particular Al Kinda, Al Farida, and Ibn Sina (Avicenna) – was largely because they – in his opinion – were not Aristotelian enough. He in fact says that Greek national philosophy is the best way to understand the physical/natural world. But the tools of natural philosophy – mathematics, logic, and demonstration – were useless as tools to understand other types of knowledge, namely religion.

    On Mathematics:

    A grievous crime indeed against religion has been committed by the man who imagines that Islam is defended by the denial of the mathematical sciences, seeing that there is nothing in revealed truth opposed to these sciences by way of either negation or affirmation, and nothing in these sciences opposed to the truth of religion.

    ReplyDelete
  5. Damned if I know why it ate the first half of that first post.
    Back in the day I wrote a uni paper on The Incoherence of the Philosophers. Surprisingly for the sometime Islamophobe that I was, I concluded that this time Islam had been given a bum rap. After reading - all in English translation - Al-Ghazali, Ibn Sina (Avicenna), and Ibn Rushd's (Averroes) The Incoherence of the Incoherence, I concluded that any stagnation that might have occurred in Science in the Islamic world could not logically be connected to Al-Ghazali. In fact his writings are full of praise for what he called the “exact sciences”.

    He just rejected the notion that the exact sciences – mathematics, medicine, astronomy – had anything to say on the higher knowledge of religion; in this instance he was following Aristotle’s hierarchy of knowledge, with metaphysics at the top followed by mathematics, and then natural philosophy (physics). But as you note, he was no fan of Aristotle’s peculiar metaphysics. al-Ghazali was scornful, seeing Aristotle as some ante-deluvian rube, whom the Muslims should not deign to stoop to. He rubbished Avicenna’s “proof” of God’s existence, as it consisted entirely of – erroneous metaphysical claims, not once resorting the falsafa’s toolbox.


    In non religious areas, however, al-Ghazali happily acknowledges that human’s can discern causation. Al-Ghazali’s attack on the Islamic followers of Greek natural philosophy (falsafa) – in particular Al Kinda, Al Farida, and Ibn Sina (Avicenna) – was largely because they – in his opinion – were not Aristotelian enough. He in fact says that Greek national philosophy is the best way to understand the physical/natural world. But the tools of natural philosophy – mathematics, logic, and demonstration – were useless as tools to understand other types of knowledge, namely religion.

    On Mathematics:

    A grievous crime indeed against religion has been committed by the man who imagines that Islam is defended by the denial of the mathematical sciences, seeing that there is nothing in revealed truth opposed to these sciences by way of either negation or affirmation, and nothing in these sciences opposed to the truth of religion.

    ReplyDelete
  6. Peter who is the first quote from? Al-Ghazali? Who ever he is, he is echoing St Augustine (particularly "On Christian Doctrine").

    On Galileo, as I understand his problem, he could not answer objections based on why we do not see parallax motion (the answer: we do, it is just the stars are so far away it was not measurable at the time, not being available to him). So he insisted beyond his capacity to back up his claims.

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  7. I don't know why, but the first part of my first post got eaten.


    Back in the day I wrote a uni paper on The Incoherence of the Philosophers.
    Surprisingly for the sometime Islamophobe that I was, I concluded that this time Islam had been given a bum rap. After reading - all in English translation - Al-Ghazali, Ibn Sina (Avicenna), and Ibn Rushd's (Averroes) The Incoherence of the Incoherence, I concluded that any stagnation that might have occurred in Science in the Islamic world could not logically be connected to Al-Ghazali. In fact his writings are full of praise for what he called the "exact sciences".

    He just rejected the notion that the "exact sciences" – mathematics, medicine, astronomy – had anything to say on the higher knowledge of religion. In this instance, he was following Aristotle’s hierarchy of knowledge, with metaphysics at the top followed by mathematics, and then natural philosophy (physics). But as you note, he was no fan of Aristotle’s particular metaphysics. al-Ghazali was scornful, seeing Aristotle as some ante-deluvian rube, whom the Muslims should not deign to stoop to. He rubbished Avicenna’s "proof" of God’s existence, as it consisted entirely of – erroneous metaphysical claims, not once resorting the falsafa’s toolbox.


    In non religious areas, however, al-Ghazali happily acknowledges that human’s can discern causation. Al-Ghazali’s attack on the Islamic followers of Greek natural philosophy (falsafa) – in particular Al Kinda, Al Farida, and Ibn Sina (Avicenna) – was largely because they – in his opinion – were not Aristotelian enough. He in fact says that Greek natural philosophy is the best way to understand the physical/natural world. But the tools of natural philosophy – mathematics, logic, and demonstration – were useless as tools to understand other types of knowledge, namely religion.

    On Mathematics:

    A grievous crime indeed against religion has been committed by the man who imagines that Islam is defended by the denial of the mathematical sciences, seeing that there is nothing in revealed truth opposed to these sciences by way of either negation or affirmation, and nothing in these sciences opposed to the truth of religion.

    ReplyDelete
  8. There is plenty of praise of science in Hume, Kant, Popper etc too. You can laud science's capacities all you like, but if you take away its core element -- belief in a structured universe that we can apprehend, including its causal processes, and so have positive knowledge of -- then you have gutted the heart of it. To use al-Ghazali's examples, if we cannot know what causes the burning bush to burn, then we cannot do science except in the most peripheral "nice game to play" sense.

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  9. Except that Science flourished after al-Ghazali.

    We need to be careful here using "Science". What we think of as Science today did not emerge until well after Newton. Up to, and including, Newton, study of the physical/material world (Natural Philosophy) was never even imagined to exist independently of metaphysics (by which Aristotle meant origins, causation, religion, and so on). Newton considered his great work was not about Science, but old fashioned natural philosophy, mathematics, and metaphysics, thus its title Philosophiæ Naturalis Principia Mathematica. He sounded remarkably like al-Ghazali


    "Gravity explains the motions of the planets, but it cannot explain who set the planets in motion. God governs all things, and knows all that is or can be done".

    Now, the falsafa's al-Ghazali was criticising, claimed they did know how Allah was working; al-Kindi, Avicenna, al-Farabi, and so on used Neoplatonic notions of emanation/illumination.

    Recall that Newton wrote more works on Theology than Science/natural philosophy. Again, sounding like al-Ghazali

    This most beautiful system of the sun, planets, and comets, could only proceed from the counsel and dominion of an intelligent and powerful Being....This Being governs all things, not as the soul of the world, but as Lord over all; and on account of his dominion he is wont to be called Lord God "pantokrator," or Universal Rule.r


    Now, as you know, I am no fan of Edward Said, and all this mewling about "Orientalism". But one thing that struck me when first reading in this area was the ubiquity of blaming al-Ghazali the decline of Science in Islam after "the Golden Age" and attributing it this al-Ghazali dude. I had already long become suspicious of people who argue about the distant past, using a sentence or a paragraph from some famous figure, and leaving it bare on the page, as though it spoke the wisdom of the ages by itself. I increasingly would respond, "well that’s five minutes of writing from one person". THAT’S ALL.

    Now, that quote from al-Ghazali you use has been used by just about every westerner who has commented on al-Ghazali going back at least to Renan, and probably even Voltaire!

    But Science in the Islamic world most definitely did not cease, let alone go into reverse from the 12th century on. In fact, significant advances in mathematics, optics, astronomy, and medicine were made after al-Ghazali, particularly in the 13th and 14th centuries, but also the 15th.

    The mistakes that Westerners make are a result of ironically swallowing Arab propaganda, and calling it Islamic or Arab Science. Looking at the issue by dividing "Islamic" into Arab, and Persian; and Sunni vs Shia reveals a far richer narrative. In fact, the most advanced astronomy the world had ever seen was carried out by Muslims in the 14th and 15th centuries, which turned up in Copernicus. But it was all done Persian Shia.

    Rather than end scientific research, al-Ghazali’s legacy was to rescue it from metaphysics. That is, Science in Islami became overwhelmingly positivist, with the mathematician, medico, astronomer, and optician relieved of always having to integrate their study of the material/physical world to the metaphysics of God and Revelation. In otherwords, in a way, al-Ghazali rescued them from the Aristotelian prison. Remember, that the Scientific Revolution in Europe was ultimately about confidence in rejecting Aristotelian metaphysics.

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  10. al-Ghazali was a Sunni: so saying that the Shia kept at it is not strong evidence against his having a baleful influence. Moreover, it can take a long time for the consequences of ideas to manifest. One can trace a direct line from Hume's scepticism about our knowledge of causation to post-modernism, but it took a couple of centuries.

    Scholasticism was already in disarray when Galileo, Kepler, etc did their stuff. I agree with the rejection of Aristotelian metaphysics as being part of the Scientific Revolution, but it was more a result of scientific discoveries and advances undermining Aristotelian physics and then its metaphysics than a cause of them.

    I also take the point about natural philosophy preceding what we know call 'science' and the Scientific Revolution being done by monotheist believers. This is why I posted on the debate between God's Will and God's Rationality. Moreover, most disciplines arose out of philosophy, that is not something unique to science.

    Why did Sunni science die off so dramatically? Why did the printing press take 3 centuries to cross from the Christian north of the Mediterranean to the Islamic south? There is a still a story here to tell.

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  11. Because there never really was much Sunni Arab science in the first place. ;)

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  12. but it was more a result of scientific discoveries and advances undermining Aristotelian physics and then its metaphysics than a cause of them.

    This certainly contributed, but I argue what as at least equally potent was the recovery of Plato, and the substitution of Platonic metaphysics for Aristotelian, with Kepler being an exemplar.

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  13. Plato is surely more of a barrier to science than Aristotle. I can see that making metaphysics more contested might provide an advantage, but not Plato as such.

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  14. Lorenzo, it was all about the universe and nature being written by mathematics - fashioned by the Demiurge - and thus its laws and reality conformed to mathematical patterns. This mathematically beautiful universe was planned by the divine craftsman, the Demiurge, which/who emanated energy from the One, which/who which was Xianized to God.

    It was this Neoplatonism that encouraged a lot of Medieval/Renaissance Natural Philosophers and Astronomers (and Mathematicians generally, whose work also included Music and Optics) of the error of Aristotelianism and especially the monstrosity of Ptolemy.

    Thus Kepler's acceptance of Copernicanism/heliocentrism saw the Sun emanating the One's goodness and mathematical perfection, which propelled celestial movements and orbits. However, the change started as far back as Nicolas of Cusa, and even earlier. We also see it in Galileo.

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  15. Which bit of Aristotelianism? Aristotelian physics or Aristotelian metaphysics? Aristotelianism does, after all, believe in an ordered universe.

    Belief in a mathematically elegant universe is clearly a boon to science. But I am not sure that is incompatible with Aristotelian metaphysics.

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