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Accommodating science: Astronomy

If science and religion do conflict, what are the points of conflict that have occurred? These tend to have arisen in historical contexts as the science evolved. I shall consider five sciences and how religion has responded to them: astronomy, or cosmology, geology, evolutionary biology and biology in general, medicine, and psychology. There are many other fields in which sciences have made claims that some religious traditions have found objectionable, though, so this is not an exhaustive list by any means.

For example, many human sciences have caused religious objections, such as archeology (especially archeology that deals with the Ancient Near East, but also archeological work done on Indian and American pasts, which Hindus and Mormons have found contrary to their sacred texts), history (which is arguably a science) and sociology (which often applies theoretical explanations to religious institutions that contradict the narratives of the religions themselves). However, the human sciences tend to involve both proponents and critics of theoretical views giving differing interpretations of events and even of the gathering of data, so in the interests of clarity, we will leave these aside.

Astronomy and religion

Once upon a time, as the fairytales begin, we believed that the world was flat, and then along came the scientists who showed that it was round. Religion, especially in the Bible, told us the world was flat, and sometime around the beginnings of modern science we learned that religion was wrong. Or so the fairytale goes. But it is, actually, a fairytale.

There is no doubt that ancient near eastern traditions of around 1000 BCE casually described the world as flat, and that these expressions found their way into the biblical sources. But in cosmopolitan societies, this was not what the educated thought. The world was known to be round by the Greeks, one of whom even calculated the circumference to a high degree of accuracy. Through Aristotle, the Arabs and the Europeans knew of the sphericity of the earth, and no sensible religious authority challenged this, apart from Lactantius (tutor to Constantine’s children) around the fourth century CE, Bishop Isidore of Seville, in the late sixth and early seventh century, and Indicopleustes, a monk in the seventh century, and they had little to no influence on later thinkers.

The really influential thinkers were the sphericists, as we might call them. Following Eudoxus, a student of Plato’s, another of Plato’s intellectual progeny, Aristotle wrote of a “two sphere” universe: where the earth was placed in the centre of a space enclosed by the outer sphere that the stars were placed upon. A second century Greek writer in Egypt, Ptolemy, developed a complicated model (a mathematical one, used for calculating the positions of the planets, sun and moon in the sky) which reign supreme in the western world until the sixteenth century, when it was challenged by Copernicus.

Although Aristotle’s model and Ptolemy’s were inconsistent, throughout this period few made much of the lack of consistency between it and Aristotle’s “four element” theory of physics – fire and air, which naturally moved up, and earth and water which naturally moved down, relative to the centre of the universe. The heavens were made of different stuff, which came to be known as the quintessence (fifth element, sometimes called the aither or ether), which was eternal and unchanging, and tended to move in the only motion which could be eternal and unchanging, in circles.

Ptolemy suggested that instead of circular motion around the centre of the universe, as Aristotle required, there had to be circles moving in circles in the heavens. He needed these to explain why planets moved the way they did (which we now know to be caused by irregular elliptical orbits). Ptolemy’s mathematics was widely accepted even as Aristotle’s physics were also, even though the two were not entirely compatible. Ptolemy was treated as a “computational technique” rather than a physical explanation, right up until the beginnings of the renaissance.

Aristotle’s physics was, for its time, relatively well elaborated and made sense of observational data. Its fourfold structure was extended to medicine (the four humours), to alchemy, and to conceptual schemes for recording and recalling information. It became, as it were, the groundwork on which all other science was done.

However, in the twelfth century, some thinkers (theologians like Oresme and Occam) started to challenge Aristotle’s physics. According to Aristotle, nothing moved except in “natural” ways (up and down) unless it was forced to by something acting on it. This raised the problem of the arrow. Arrows move up and down, and horizontally (in what was called “rectilinear motion”). According to Aristotle’s physics, to move up when they should move down, and to move horizontally, there had to be a moving force, and there was none. Aristotle explained this by the air moving behind the arrow to fill up the space left (because vacuums are impossible, according to Aristotle) imparted a force that kept it moving.

This was rather a forced explanation, and few were happy with it. Oresme and Occam (who is famous for his Razor) noted that barges would continue to move in water after being pushed, and came up with the idea of a conserved force they called “impetus” instead. Here is a case of religion and science in conflict. As theologians, Oresme and Occam (and other theologians of the time) felt it was their duty to revise and correct ideas about the natural world, especially those that came from pagan sources. And yet, their correction was more correct than Aristotle’s ideas were; in short, they advanced science.

Later, another theologian and priest, Nicholas Copernicus, proposed the idea that the earth revolved (in our terms, orbited; “rotation” applies to the earth’s daily rotation around the polar axis, while “revolution” applies to the movement of one heavenly body around another) around the sun (heliocentrism). Again, this is a case of a theological conflict with the science. Philosophically, Copernicus was somewhat influenced by neo-Platonic ideas in which physical things reflected a transcendental order, and the sun, being the source of light, must therefore represent the light of knowledge (Kuhn 1959). It is unclear how influenced Copernicus was (Rosen 1983), but that there was some influence is, I think, likely.

So we come to Galileo. The idea of a sun-centred universe is often called, following Kuhn, the “Copernican Revolution” (this being a historian’s double entendre), but as revolutions go, it was as slow as that of Saturn. Copernicus published in 1543, and Galileo in 1632, and by his death in 1642, 99 years after Copernicus’ own death, many but not all astronomers had adopted heliocentrism. Political revolutions that take so long are called reform movements; I suggest we should think that this is also a reform movement in astronomy.

As I noted, Galileo’s error lay in not realising that the usual Catholic theological tradition of reinterpreting scripture to cope with science was something he could not employ. Instead he had to get the Church to employ that. He made the mistake of telling theologians how to interpret scripture. Let me make one thing clear, though; he was not censured because he said the earth went around the sun. He was censured because he taught that the Church was wrong about how to read scripture, at a time when that was the bone of contention between the Church and the Protestants. In short, Galileo fell afoul of internal Church politics in a theological dispute about what the magisterium of the Church was.

However, the heliocentric theory was widely adopted and extended in Catholic as well as Protestant countries, and within another century had taken over, with little to no criticism by the Church.* However, some bemoaned the loss of the old certainties, such as John Donne in his poem “An Anatomy of the World” in 1611:

And new philosophy calls all in doubt,
The element of fire is quite put out,
The sun is lost, and th’earth, and no man’s wit
Can well direct him where to look for it.
And freely men confess that this world’s spent,
When in the planets and the firmament
They seek so many new; they see that this
Is crumbled out again to his atomies.
’Tis all in pieces, all coherence gone,
All just supply, and all relation; [lines 205-214]

All coherence was gone now, with this new science (“philosophy”) that dissected phenomena. This has more to do with the aesthetics of intellectual systems than religion as such. In any case, the conflict between religion (the Church) and science (astronomers) was not greatly effective in halting science here, nor would a lack of opposition made much difference in the advancement of heliocentrism, in my opinion.

Newton, another well-known religious enthusiast, although he was a unitarian or Arian rather than an orthodox Trinitarian, cemented the heliocentric theory – and extended it way beyond what either Copernicus or Galileo might have expected – and established a new physics that would completely replace the old four-elements two-sphere universe of Aristotle. Coherence was achieved again. But notice that it was achieved in 1687, a full 144 years after Copernicus’s death and publication. In each step, and I have left out a good many which can be found in such histories as Koestler’s (1964) or Toulmin and Goodfield’s (1962), religion was not always or even often a scientific inhibitor or barrier.

In subsequent developments, Napoleon famously asked his old teacher, Laplace, where God was in his book on astronomy, to which Laplace famously replied “I have no need of that hypothesis, sire”. The context changes it slightly from the usual interpretation, however. Newton could not explain why the solar system was stable, and he imposed God’s action, possibly via angels, to make sure the system did not collapse over time. Napoleon, who had studied physics and astronomy with Pierre Laplace, knew this, and when Laplace worked out that such a system could be stable without intervention, he dropped God’s intervention. It was this that Napoleon picked up on. Laplace was not rejecting God, so much as pointing out that God was a hypothesis of last resort.

In each of these episodes we see that the issue is not really religion against science, but either religion against other religion or old science against new science. Religions, unlike sciences, however, have a strong conservative aspect, and so once a view has been given a red light by a religious tradition, it can take a very long time for the religion to adapt to the new science it once objected to.

The religious views of the scientists involved do not seem to have had much if any real impact on the science itself. Newton did not present an Arian view of the solar system; Galileo did not contrast his religious beliefs with Protestant astronomy. In fact, quite the opposite: religious differences played almost no role in these debates unless they were religious issues being debated. Science, it seems, has always been secular even in the most contentious periods of religion in the west.


Koestler, A. (1964). The sleepwalkers: a history of man’s changing vision of the universe. Harmondsworth, Penguin by arrangement with Hutchinson.

Kuhn, T. S. (1959). The Copernican revolution: planetary astronomy in the development of Western thought. New York, Vintage Books.

Rosen, E. (1983). “Was Copernicus A Neoplatonist?” Journal of the History of Ideas 44(4): 667-669.

Toulmin, S. and J. Goodfield (1962). The Fabric of the Heavens: the development of astronomy and dynamics. Chicago, University of Chicago Press.

* The Church issued prohibitions until 1664, but by 1758 had dropped heliocentrism from the Index. Rabbinic opposition took about the same delay to abate.


  1. Copernicus was a cannon of the cathedral chapter in Frauenburg but he was never ordained as a priest.

  2. jeb jeb

    “But it is, actually, a fairytale.”

    “I believe that the Irish intelligentsia had a specific reason for accepting the Antipodes: their desire to accommodate as many possible of their inherited beliefs to the prestigious and exciting world view afforded by Christian revelation and Graeco-Roman Science.”

    Relationship between flat earth and the antipodes is a tangled one. Article seems on topic. A rural rather than urban elite at play.

    Ireland and the Antipodes: The Heterodoxy of Virgil of Salzburg
    John Carey Speculum Vol. 64, No. 1 (Jan., 1989), pp. 1-10

  3. Nick Nick

    He needed these to explain why planets moved the way they did (which we now know to be caused by irregular elliptical orbits). -> not really it’s mostly the different speeds of the planets as they pass each other that makes them appear to reverse course in the sky temporarily.

  4. “There is no doubt that ancient near eastern traditions of around 1000 BCE casually described the world as flat, and that these expressions found their way into the biblical sources.”

    I’d be interested in your specific evidence for this claim, John. (Contrary to your statement, I do entertain “doubt” about this.)

    Also: I question whether it’s proper to label the Galileo/Copernicus business as a true “religion versus science” episode. My understanding is that neither Copernicus nor Galileo had actual scientific (empirical) evidence at the time to support their heliocentric theorizing. Galileo thought he had a scientific case, using an argument about tides, but he was mistaken. Only later on did valid scientific evidence emerge. Do you see it differently?

    • TomS TomS

      I’m interested in what was the first scientific evidence for heliocentrism.

      For that matter, what is the scientific evidence against today’s geocentrists?

      • TomS TomS

        Do people think that there isn’t truly scientific evidence for heliocentrism until the 19th (or 20th) century for the same that there is a difference from historical and other science? “How do know about space? Are you there?”

        • Michael Fugate Michael Fugate

          There are a number of historians who would claim this is true. See the Renaissance Mathematicus blog archives for numerous comments on this. I know because I once brought up this very question there and was slammed as a complete idiot for even suggesting it. We do know that heliocentric ideas were floating around in Greece (e.g. Aristarchus), but the geocentrist Ptolemy wrote the history of astronomy to that time. We don’t have a complete record of astronomical history and of course we have our own modern biases to impose.

          One of the biggest issues seems to be the concept of inertia – which allows for things on a moving earth to be moving at the same speed. There is also an issue with the distances to the planets and stars which were thought to be much nearer and therefore much smaller. Aristarchus’ suggestion that that could be very far away was rejected; it was hard to imagine the actual distances. Of course, Aristotle’s physics was also a problem with the earth being the heaviest body and objects falling toward it.

          As with the fossil record, we don’t know all the ideas that were put forward and the arguments for and against them. We also need to remember that no telescopes existed until very late, early telescopes were not very good – only as good as the lenses, circular orbits are a problem for heliocentrism too. The Greeks also weren’t experimentalists for the most part.

  5. TomS TomS

    So, what was the first truly scientific evidence for heliocentrism, and what is the best evidence that we have today?

    • I would think the first real evidence was the observation of the phases of Venus and the differences in apparent size, which showed that it, at any rate, went around the sun. Of course that still left the Tychoan scheme but that was dismissed because once you had one planet going around the sun, there was no longer any reason to think other planets, including ours, could not orbit the sun.

      • TomS TomS

        I guess that the first was that things in the heavens were ordinary things – the Moon had mountains, the Sun had spots (and rotated), Jupiter had own moons, and, in general, they could be studied. And that it was possible to treat the Earth like the “other” planets. What stopped the Earth from being a planet?

        This, I recognize, is not “truly scientific” in the way that would like science be like. Thus my taunt about “are you there”.

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