Conflict Myths: Galileo Galilei

This essay is the first in a series which explores historical encounters which are often presented as conflicts between science and Christianity.


This article has been expanded – the full version can be found here.


“The laws of nature are written by the hand of God in the language of mathematics” – Galileo Galilei (Il Saggiatore, 1623)

Galileo Galilei (1564 – 1642) was a brilliant mathematician, astronomer and physicist. He was appointed to the chair of Mathematics at the University of Pisa in 1589, and spent the next 20 years conducting excellent astronomical observations and making significant discoveries in pure and applied science. He did groundbreaking work in the mechanics of falling bodies under gravity (although, contrary to that other myth, he never dropped anything off the Tower of Pisa), and made significant improvements to the design of telescopes. In 1610 he published his observations of the moons of Jupiter, and it is at this point that our interest in him really starts.

Astronomical understanding in the early 17th century was still rooted in the Aristotelian model, the core of which was that the heavens were composed of concentric circles, with the Earth at the centre. The celestial bodies themselves were perfect circles made of “incorruptible aether” and were eternal – subject neither to generation nor decay.

This was the reigning scientific model which the secular universities were adamant to maintain, but Galileo’s observations of sunspots and lunar craters cast doubt on the “perfect circles”, and his observation in 1604 of a supernova contradicted the immutability of Aristotle’s heavens. Moreover, his observations of Jupiter’s moons challenged the notion that all celestial bodies orbit the Earth. Galileo endorsed the heliocentric system developed by Nicolaus Copernicus, a Catholic priest who published his De revolutionibus orbium coelestium in 1543.

In 1611 Galileo travelled to Rome to present his findings, and was greeted with great acclaim. He demonstrated his observations of Jupiter to Christopher Clavius, a Jesuit at the Collegio Romano and the most respected astronomer in Europe at the time, who confirmed Galileo’s observations and parts of his theses of planetary motion.

The secular university professors were not as accommodating to this activity as the Jesuits had been, however. After several years spent as a public advocate for the Copernican theory, Galileo wrote in his famous Letter to the Grand Duchess Christina in 1615 that his theories had “stirred up against me no small number of professors”, and that these academics had agitated strongly for ecclesiastical support in their cause.

This letter is also an excellent illustration of some personal aspects of Galileo. He was monumentally arrogant, belligerent and abrasive towards any who opposed him. He wrote concerning the professors:

“I should pay no more attention to them than to those who previously contradicted me – at whom I always laugh, being assured of the eventual outcome.”

It was in this letter, also, that Galileo himself defined the astronomical debate as being irrevocably rooted in interpretation of the Bible. Under pressure from both sides of the dispute, the Church was drawn into the fray. Cardinal Maffeo Barberini, the future Pope Urban VIII and a friend of Galileo, cautioned him to drop the matter. Cardinal Roberto Bellarmino, the “Consultor of the Holy Office and Master of Controversial Questions” (don’t you just love that title?), wrote a letter to Galileo in April 1615 outlining the Church’s official position. He pointed out that Copernican theory was perfectly acceptable as a working hypothesis, and if there were proof that the earth circles around the sun, “then we should have to proceed with great circumspection in explaining passages of Scripture which appear to teach the contrary.”

In effect, he challenged Galileo to offer some proof for his theory or stop pestering the Church publicly with it, but that if proof were offered he was open to hearing it.

(Interestingly, the heliocentric model had been considered by Aristotle and rejected – he wrote that under such a system we should see stellar parallaxes. In other words, the change of position of the earth from one side of its orbit to the other should change the relative positions of the stars in different seasons. The scientific strength of this objection is illustrated by the fact that stellar parallax was only observed in 1838 by Friedrich Bessel.)

Galileo had no astronomical proof to offer, partly because his own observations did not align properly with his theory. He insisted that planets move in perfect circles (based on Aristotle’s hypothesis) and rejected the theories of Johannes Kepler, who proposed in his Astronomia nova (1609) that planetary orbits are elliptical. Instead, Galileo proposed as proof a flawed and unconvincing theory that the tides were evidence of the Earth’s rotation (and, incidentally, specifically denying that lunar attraction was involved). In 1616 the Church ordered him to cease and desist his public advocacy of the unproven theory.

For the next seven years, Galileo acquiesced to the Church’s injunction, but in 1623 his friend and supporter Maffeo Barberini ascended to the papacy, and Galileo confidently re-entered the public fray.  In the same year he published Il Saggiatore (“The Assayer”), in which he launched a vicious assault on a treatise on comets by Orazio Grassi, a Jesuit mathematician at the Collegio Romano. Grassi used observations of parallax to argue that comets are further away than the moon; Galileo ridiculed this idea and claimed rather that comets are an optical illusion. His factual error notwithstanding, the harshness of Galileo’s tone permanently soured his relations with the Jesuit order. Pope Urban VIII thoroughly enjoyed the rhetorical flourishes of Galileo’s prose, however, and composed a poem in his honour.

Like Galileo, Urban was a vain and irascible man. After listening to Galileo’s arguments for years, he declared that the possible ways of arranging the universe were so numerous that it was impertinent for mortals to claim that they had discovered the unique truth. He insisted that Galileo include the Aristotelian alternative in his presentations of the universe.

In 1632, Galileo published his response to these arguments:  Dialogue Concerning the Two Chief World Systems. In it, he presented his astronomical theories as a conversation between Salviati, who is referred to as “the Academician” and represents Galileo’s own views; and Simplicio (or “The Fool”), who bumbles about and contradicts himself as he ineptly offers a straw-man version of the Aristotelian / Ptolemaic perspective – and more importantly, represents the Pope’s views.

Not too surprisingly, this didn’t go down very well with the Pope. His hubris and vanity would not tolerate public ridicule, and Galileo was called before the ecclesiastical court. He was condemned by the Catholic Church as “suspected of heresy” – about the strongest charge that could be brought, since Copernicanism had never been declared heretical – and was then whipped tortured killed burned housed with a personal valet in a luxurious apartment overlooking the Vatican gardens. He spent the remainder of his life in comfort (albeit technically under house arrest), working on his final masterpiece, Discourses and Mathematical Demonstrations Relating to Two New Sciences. Published in 1638, this book was the grand summation of much of his work in physics over the preceding thirty years.


Conflicting opinions

So what shall we make of this tale? Although our 21st century perspective makes us indignant that the “truth” was being muzzled and declared heretical, I think there are some important misconceptions in that attitude:

  • First, the obvious: Despite the fact that prominent atheists love to invoke Galileo as an example of the supposed “conflict” between science and religion, Galileo was a Christian. He responded to the secular professors who attacked his theory from a distinctly Christian perspective: in Letter to the Grand Duchess he invokes arguments by St Augustine and Thomas Aquinas regarding Biblical interpretation.
  • Although we view Galileo’s theories as an obvious improvement over the Aristotelian model of a geocentric solar system, it is important to reiterate that this was not provable by Galileo’s own evidence. His observations of the moons of Jupiter and the craters of the moon suggested problems with the pure geocentric model, but he certainly could not prove his case. In fact, an objection could have been made on purely scientific grounds that the heliocentric model offered insufficient improvement in explanatory power to justifiably replace the reigning paradigm.
  • I make no excuses for the Pope’s abuse of his position to silence a critic, but the church’s treatment of Galileo was remarkably restrained by the standards of 17th century Europe. Giorgio de Santillana, Professor of Humanities at MIT, wrote that “We must, if anything, admire the cautiousness and legal scruples of the Roman authorities”. The philosopher Alfred North Whitehead wrote:

“In a generation which saw the Thirty Years’ War and remembered Alva in the Netherlands, the worst that happened to men of science was that Galileo suffered an honourable detention and a mild reproof, before dying peacefully in his bed.”

Consider, in closing, this analogy:

John is a brilliant employee in a major corporation. He is also in charge of producing the company newsletter. The CEO of the company holds a view that John disagrees with. John publishes an article featuring a caricature of the CEO named “Retard Boy”. He gets fired.

The point in that scenario is not whether John’s views will eventually be proved right by later scientific discovery – he still exercised supremely poor judgement.

Conflict Myths: Series Overview

This series explores key historical encounters which are often presented as “conflicts” between science and Christianity.

I believe that the perceived “conflict” is overwhelmingly based on a revisionist presentation of history, as well as fear and misunderstanding on both sides of the discussion. My intention is to explore the actual events and characters involved in each case, and understand them in their proper historical context.

Essays in this series include:

  1. Galileo Galilei
  2. Bishop Ussher
  3. Wilberforce and Huxley

On reading both books

Last night a friend posed an interesting challenge to the question of whether science and religion can be properly reconciled. His issue was not with any particular theory, it was rather a challenge in principle to the notion that the immutable truth of God’s word could ever be fully reconciled with the continual change and adaptation of scientific theory. The Bible doesn’t change, but our understanding of the universe does – how can these be fully compatible? It’s an interesting question and a fresh take on the problem.

Francis Bacon, the founder of the modern Scientific Method, said that to understand the world we needed both books that God has provided: the Bible and the “book of Nature”. I mention this because it seems to me that it is in this duality of revelation that we find our answer.

When we first read a Biblical passage, it may be opaque or it may have immediately obvious meaning. But further study of the surrounding text and the context in which the passage was written will bring a deeper and fuller understanding. It is not dissimilar to science, where study in a particular field advances and builds on previous understanding. The Biblical text does not change, but our understanding of it does. Likewise, the underlying principles and workings of the universe do not (as far as we know) change, but our understanding of them grows with further study.


A multidisciplinary approach

Closely related is the issue of uniform literalism in biblical interpretation, so let’s consider that as well:

The study of the “book of Nature” (or ‘Science’, for short) is not limited to a single discipline. At the most basic level, there are different techniques for experimental science (e.g. chemistry, quantum physics) and for observational / historical sciences (such as palaeontology or cosmology). To even attempt to use the techniques from one discipline in another is often impossible. We understand that there are appropriate ways of assembling and analysing data and of testing hypotheses, and we limit our techniques to those appropriate to our field of study.

Similarly, the Bible is not limited to a single style of writing. But there are clearly sections of history, sections of poetry, and sections of philosophy. Sometimes these overlap: the opening chapters of Genesis in particular are a poetic presentation of some fundamental (and actually very radical) philosophy and theology. They describe the nature of the universe and God’s relation to it, and give a philosophical explanation of the human predicament as an inevitable outworking of free choice. It is not a scientific treatise in itself, but interestingly it does provide a foundation for viewing the world scientifically. It indicates that the universe was created and is ordered by God, who exists outside of the universe but also sustains it. Importantly, it says that the created universe is not divine and is not to be worshipped: instead, it can be studied.

Works like Chronicles, Samuel, etc – and most importantly for Christianity, the Gospels and Acts – are historical. They record literal events in history. Archaeology and literary analysis of various sources (including records of historians ambivalent or hostile towards Christianity) can be applied to the historical statements in these books, and their veracity can be demonstrated. The evidence for these books is relevant to how seriously we take them, and any honest evaluation of the evidence indicates that their historical accuracy is extraordinary.

But to look at a passage in Isaiah such as: “The mountains and hills will burst into song before you, and all the trees of the field will clap their hands”, and say, “Well, that cannot be literally true and thus the resurrection must also be just a fable,” indicates a gross misunderstanding of the material under study.


An unorthodox view

Reflecting on Galileo’s clashes with the scientific and religious establishments of his day (about which read more here), John Lennox observed the following:

“Ironically, it was Galileo, a believer in scripture, who correctly challenged the reigning scientific paradigm in the name of science. One important lesson is that those of us who take the biblical account seriously should be humble enough to distinguish between what the Bible says and our interpretations of it. The biblical text just might be more sophisticated than we first imagined, and we might therefore be in danger of using it to support ideas that it never intended to teach.” (“Challenges from Science” in Beyond Opinion, edited by Ravi Zacharias)



Related posts:

On Spherical Cows and the Search for Truth

Believing and understanding

Seeing the gardener