The Griffith Observatory in Los Angeles. Image by Todd Lapin, CC-BY-NC 2.0, here.
One of the things that the Catholic Church gets accused of ad nauseam is the fact that the Inquisition accused and convicted Galileo for teaching that the Earth rotated around the Sun. However, many people who criticize the Church’s alleged hostility to science overlook the fact that Galileo was not able to prove his theory back then, but he insisted on teaching it as fact. Not only that, his theory was actually refuted by the science of his day. In this article, I am providing reasons to be less harsh at Church officials for being against Galileo.
Paul Feyerabend (1924-1994) was an Austrian philosopher specializing in the philosophy of science. He taught philosophy of science at University of California, Berkeley for about 31 years.
In 1975, he published a book with the title “Against Method: Outline of an Anarchistic Theory of Knowledge”. In it, he explained his theory of “epistemological anarchism”.
Epistemology means the branch of philosophy dealing with knowledge, its nature and its limitations. There is a problem known in this field known as the “demarcation problem”. What is the difference between science and pseudoscience? “Epistemological anarchism” is the idea that there are no always valid criteria to judge whether something is science or pseudoscience.
Feyerabend demonstrates this idea on Galileo Galilei (1564-1642): if one applies modern scientific criteria to Galileo, he fails.
We need to keep in mind that the entire issue of Galileo happened in the beginning of the 17th century. People didn’t have the same knowledge of science as people do now. For example, Newton’s three laws of motion were first published in 1686 in his book “Principia Mathematica Philosophiae Naturalis”. Feyerabend demonstrates in his book that according to the understanding of science back then, Galileo’s theory of heliocentrism was falsified (“falsified” is a scientific term meaning “refuted”).
Galileo’s theory was refuted by the science of his day
Galileo’s opponents at the time falsified his theory.
What they did was very simple: go up to a tower, and drop a rock. The rock will fall in a straight line, as expected if the Earth was stationary. If the Earth was moving, the rock should fall further and further from the tower before hitting the ground.
Again, this was before Newton discovered the laws of motion. Now we of course know that the rock is also traveling with the same speed as the earth is rotating, and due to inertia, keeps that speed when it is released. So it falls in a straight line (minus the tiny effect of air resistance).
In the context of the science as it was at the start of the 17th century, Galileo was refuted by a very basic experiment. And how did he reply? He didn’t have much of an answer.
Galileo and his telescope
Galileo was the first person to use the recently invented telescope for astronomical research. He discovered the four largest moons of Jupiter and inferred that the Earth rotates around the Sun just like those moons rotate around Jupiter.
Imagine that you are a physicist and someone comes to you that many things people understood about physics for many centuries is wrong, because he has some kind of new device. But only he and a few other people have that device. That is the situation scientists encountered in the 17th century when Galileo showed them the telescope and claimed that that device changes everything.
As Feyerabend puts it: “However, he offers no theoretical reasons why the telescope should be expected to give a true picture of the sky.” (p. 77)
“A little later Galileo notes that ‘they [the Copernicans] were confident of what their reason told them!’ And he concludes his brief account of the origins of Copernicanism by saying that ‘with reason as his guide he [Copernicus] resolutely continued to affirm what sensible experience seemed to contradict’. ‘I cannot get over my amazement’, Galileo repeats, ‘that he was constantly willing to persist in saying that Venus might go around the sun and might be more than six times as far from us at one time as at another, and still look always equal, when it should have appeared forty times larger.[’] The ‘experiences which overtly contradict the annual movement’, and which ‘are much greater in their apparent force’ than even the dynamical arguments above, consist in the fact that ‘Mars, when it is close to us … would have to look sixty times as large as when it is most distant. Yet no such difference is to be seen. Rather, when it is in opposition to the sun and close to us it shows itself only four or five times as large as when, at conjunction, it becomes hidden behind the rays of the sun.’” (p. 79-80)
The problem of why the apparent size of the planets on the sky doesn’t change much during the course of their orbits around the sun was only solved relatively recently. The angular size of the planets is proportional to their distance, but not with such a higher factor as was thought in the 17th century (see the book for details).
Another problem with using telescopes is that the people at that time didn’t know for certain that it works the same way when looking at space: they weren’t sure it represented planets the same way it did objects on Earth. Yes, a telescope can of course be used on Earth to see far-away objects, like Galileo himself demonstrated in 1611 in Rome (p. 84). However, this did not give enough evidence that it is reliable visualizer of outer space.
Feyerabend summarizes: “His telescope gave surprising results on the earth, and these results were duly praised. Trouble was to be expected in the sky, as we know now. Trouble promptly arose: the telescope produced spurious and contradictory phenomena and some of its results could be refuted by a simple look with the unaided eye. Only a new theory of telescopic vision could bring order into the chaos (which may have been still larger, due to the different phenomena seen at the time even with the naked eye) and could separate appearance from reality. Such a theory was developed by Kepler, first in 1604 and then again in 1611.” (p. 99) The book describes how the calculations of Kepler were refuted by a simple experiment. A description would be out of scope of this article.
In other words, Galileo didn’t have any proof that the telescope was an accurate representation of reality, and the only test was negative.
Feyerabends’ conclusion
Feyerabend observes that “science” is a complicated “historical process which contains vague and incoherent anticipations of future ideologies side by side with highly sophisticated theoretical systems and ancient and petrified forms of thought.” (p. 107)
He suggests that in order for science to progress, one must propose new theories, even if they are contradicted by observations. According to him, sometimes one must use irrational methods “such as propaganda, emotion, ad hoc hypotheses, and appeal to prejudices of all kinds. We need these ‘irrational means’ in order to uphold what is nothing but a blind faith until we have found the auxiliary sciences, the facts, the arguments that turn the faith into sound ‘knowledge’.” (p. 114)
“Moreover, the cosmologists of the 16th and 17th centuries did not have the knowledge we have today, they did not know that Copernicanism was capable of giving rise to a scientific system that is acceptable from the point of view of ‘scientific method’. They did not know which of the many views that existed at their time would lead to future reason when defended in an ‘irrational’ way.” (p. 116)
Feyerabend on the role of the Church
When it comes to the role of the Catholic Church, Feyerabend, who was raised Catholic, thinks that “[t]he Church at the time of Galileo not only kept closer to reason as defined then and, in part, even now; it also considered the ethical and social consequences of Galileo’s views”. (p. 125) (Chapter 13)
“Besides, the Church, and by this I mean its most outstanding spokesmen, was much more modest than that. It did not say: what contradicts the Bible as interpreted by us must go, no matter how strong the scientific reasons in its favour. A truth supported by scientific reasoning was not pushed aside. It was used to revise the interpretation of Bible passages apparently inconsistent with it. There are many Bible passages which seem to suggest a flat earth. Yet Church doctrine accepted the spherical earth as a matter of course. On the other hand the Church was not ready to change just because somebody had produced some vague guesses. It wanted proof – scientific proof in scientific matters. Here it acted no differently from modem scientific institutions: universities, schools and even research institutes in various countries usually wait a long time before they incorporate new ideas into their curricula. (Professor Stanley Goldberg has described the situation in the case of the special theory of relativity.) But there was as yet no convincing proof of the Copernican doctrine. Hence Galileo was advised to teach Copernicus as a hypothesis; he was forbidden to teach it as a truth.
This distinction has survived until today. But while the Church was prepared to admit that some theories might be true and even that Copernicus’ might be true, given sufficient evidence, there are now many scientists, especially in high energy physics, who view all theories as instruments of prediction and reject truth-talk as being metaphysical and speculative.” (p. 132-133)