Galileo and the Inquisition

William E. Carroll

The myth that science and religion are incompatible seems to be confirmed by the condemnation of Galileo. William E. Carroll, Aquinas Fellow in Science and Religion at Blackfriars Hall, Oxford, examines this case and concludes: ‘The Inquisition did not ask Galileo to choose between science and faith.’

There are few images of the modern world more powerful than that of the humbled Galileo, kneeling before the cardinals of the Inquisition, being forced to admit that the Earth did not move. The story is a familiar one: that Galileo represents science’s fighting to free itself from the clutches of blind faith, biblical literalism, and superstition. The story continues to fascinate people in our own day as much as it has fascinated people in every generation. As is often the case, the legend of Galileo’s encounter with the Inquisition has often proved to be more powerful than the historical reality itself.

The famous Galileo codex, which contains most of the documents concerning the Inquisition’s treatment of Galileo, was preserved as a result of Napoleon’s interest in Galileo. When Napoleon seized the Vatican archives in 1810 – and ordered them to be shipped to Paris to be part of a new centre of European culture – he made a point of having the material on Galileo sent by imperial courier, lest it be lost. Napoleon saw himself as a kind of political Galileo who was ushering in a new order in the political cosmos of Europe, and who, like Galileo, was opposed by the Church.

The spectre of the Catholic Church’s condemnation of Galileo continues to occupy a prominent place in the modern world’s understanding of the relationship between religion and science. On the occasion of the publication, in March 1987, of the Church’s condemnation of in vitro fertilisation, surrogate motherhood, and foetal experimentation, there appeared a page of cartoons in one of Rome’s major newspapers, La Repubblica, with the headline: ‘In Vitro Veritas’. In one of the cartoons, two bishops are standing next to a telescope, and in the distant night sky, in addition to Saturn and the moon, there are dozens of test-tubes. One bishop turns to the other, who is in front of the telescope, and asks: ‘This time what should we do? Should we look or not?’ The historical reference to Galileo was clear.

In fact, at a press conference at the Vatican, Cardinal Joseph Ratzinger was asked whether he thought the Church’s response to the new biology would not result in another ‘Galileo affair’. The Cardinal smiled, perhaps realising the persistent power – at least in the popular imagination – of the story of Galileo’s encounter with the Inquisition more than 350 years before. The Vatican office which Cardinal Ratzinger now heads, the Congregation for the Doctrine of the Faith, is the direct successor to the Holy Roman and Universal Inquisition into Heretical Depravity.

Formal acceptance
In October 1992, Pope John Paul II appeared before the Pontifical Academy of Sciences to accept formally the findings of a commission of historical, scientific, and theological inquiry into the treatment of Galileo by the Inquisition in the seventeenth century: a commission which he established in the early 1980s. The Pope noted that the theologians of the Inquisition who condemned Galileo failed to distinguish properly between particular interpretations of the Bible and questions which in fact pertained to scientific investigation.

The Pope also observed that one of the unfortunate consequences of the condemnation of Galileo was that it has been used to reinforce the myth of an incompatibility between faith and science. That such a myth is alive and well was immediately apparent in the way the press described the event in the Vatican. The headline on the front page of The New York Times was representative: ‘After 350 Years, Vatican Says Galileo Was Right: It [the Earth] Moves’.

Galileo’s story
Galileo was born in Pisa in 1564: the same year in which Michelangelo died and Shakespeare was born. It was 21 years after the publication of Copernicus’ treatise on heliocentric astronomy; and 47 years after the appearance of Luther’s 95 theses and the beginning of the Reformation. In fact, the Protestant Reformation, the Catholic response – especially the Council of Trent, whose final session ended in 1563 – the destruction of the religious unity of Europe, and the ensuing wars of religion constituted the world in which Galileo would spend his entire life.

Galileo’s telescopic observations convinced him that Copernicus was correct. In The Starry Messenger, published in 1610, he reported his discoveries that the Milky Way consists of innumerable stars, that the Moon has mountains, and that Jupiter has four satellites. Subsequently, he discovered the phases of Venus and spots on the surface of the Sun. He named the moons of Jupiter the ‘Medicean Stars’ and was rewarded by Cosimo de’ Medici, Grand Duke of Tuscany, with appointment as chief mathematician and philosopher at the Duke’s court in Florence. The telescopic discoveries, and arguments derived from them, served Galileo well in his public defence of Copernicus’ thesis that the Earth and the other planets revolve about the Sun.

When we speak of Galileo’s defence of the thesis that the Earth moves, we must be especially careful to distinguish between arguments in favour of a position, and arguments which prove a position to be true. In fact, Galileo and the theologians of the Inquisition accepted the prevailing Aristotelian ideal of scientific demonstration which required that science be sure and certain knowledge in terms of necessary causes, not the conclusions of hypothetical or probabilistic reasoning which today we tend to accept as science. Galileo, despite his disagreements with many seventeenth-century Aristotelians, never departed from Aristotle’s ideal of science as sure, certain knowledge. Whether he was arguing about the movement of the Earth or about laws that govern the motion of falling bodies, his goal was to achieve true, scientific demonstrations. When Galileo wrote his Two New Sciences, near the end of his life, he argued that he deserved credit for establishing new sciences because his arguments employ ‘necessary demonstrations’ which proceeded from ‘unquestionable foundations’.

It is especially important to recognise that Galileo, himself, did not think that his astronomical observations provided sufficient evidence to prove that the Earth moves, although he did think that they called into question the truth of Ptolemaic astronomy. Galileo hoped eventually to argue conclusively from the fact of ocean tides to the double motion of the Earth as the only possible cause, but he did not succeed.

Implications for biblical interpretation
Galileo visited Rome on several occasions early in the second decade of the seventeenth century; he discussed his telescopic observations with Jesuit professors at the Collegio Romano and with members of the church hierarchy, and early on he was very warmly received. In 1615, as the controversy over the new astronomy, and especially its implications for biblical interpretation, had become increasingly public, Cardinal Roberto Bellarmino, the learned Jesuit theologian and member of the Inquisition, told Galileo that if there were a true demonstration for the motion of the Earth then the Church would have to abandon its traditional reading of those passages in the Bible which appeared to be contrary.

But, in the absence of such a demonstration, and in the midst of the controversies of the Protestant Reformation, the Cardinal urged prudence: treat Copernican astronomy simply as a hypothetical model which accounts for the observed phenomena. It is clear in the Cardinal’s comments that he did not think that the immobility of the Earth was a matter of church doctrine. If Bellarmino had thought it were a matter of faith, he could not have argued, as he did, that it might be possible to demonstrate that the Earth does move. For then he would have argued that scientific truth could contradict the truth of faith.

When Bellarmino spoke of treating Copernican astronomy as a hypothesis, he was using a commonly accepted notion of mathematical astronomy, in which devices such as epicycles and eccentrics, characteristic of Ptolemaic astronomy, were geometrical constructs to describe observed movements in the heavens. He distinguished this mathematical astronomy from what we might call a physical astronomy, which had as its goal a true account of what the heavens were and how they moved. Thus, the Cardinal wrote in 1615, in a passage to which I have already referred, ‘if there were a true demonstration’ that the Earth moved about the sun, then biblical interpretation would have to be adjusted accordingly. This distinction between ‘saving the appearances’ and demonstrating the truth, is a distinction Galileo shared with Bellarmino. Galileo, as he himself said, was not interested in ‘saving the phenomena’, he sought to discover ‘the true constitution’ of the universe.

The opposition within scientific circles in the early seventeenth century to claims that the Earth moved was generally based on the assumption that a geocentric astronomy was an essential part of a larger Aristotelian cosmology: the view, that is, that Aristotelian physics and metaphysics depended in some way on the affirmation that the Earth was immobile at the centre of the universe. Thus, if one were to reject such a geocentric astronomy, then, so it seemed to many, the whole of Aristotelian science would have to be discarded. As a result of such an understanding, or, really, misunderstanding, of the interdependence of astronomy, cosmology, physics and metaphysics, some thought that the acceptance of a moving Earth would involve a radical philosophical revolution. Hence, we might understand why many of Galileo’s contemporaries were so troubled by his support for Copernican astronomy.

Furthermore, although we now accept without question that the Earth moves, we need to guard against assuming that it is a simple matter to reach this conclusion and that, therefore, the scientific opponents of Galileo were either simple-minded or stubbornly blind to the truth.

An understanding of the theological dimensions of the encounter between Galileo and the Inquisition requires that we keep in mind this question concerning the scientific knowledge of the motion of the Earth. All sides in the controversy were committed to the Aristotelian ideal of scientific knowledge. Remember, Cardinal Bellarmino told Galileo that if there were a demonstration for the motion of the Earth, then the Bible would have to be interpreted accordingly. The Cardinal has simply reaffirmed traditional Catholic teaching that the truths of science and the truths of faith cannot contradict one another.

Chief scientist for the Medici
Galileo addressed the question of the relationship between science and the Bible in his famous Letter to the Grand Duchess Christina. Galileo was the chief scientist in the employ of the Medici family and Christina of Lorraine was the mother of the reigning Grand Duke. The letter contains Galileo’s account of the recent controversy over the claims of Copernican astronomy. He composed it in 1615 in the midst of the debate concerning the relationship between traditional interpretations of the Bible and the view that the Earth moves. Galileo was increasingly concerned that the Church would condemn the conclusions of Copernicus.

One representative passage is illustrative of the general tenor of Galileo’s remarks throughout the letter:

I think that in disputes about natural phenomena one must begin not with the authority of scriptural passages, but with sensory experience and necessary demonstrations. For the Holy Scripture and nature derive equally from the Godhead, the former as the dictation of the Holy Spirit and the latter as the obedient executrix of God’s orders; moreover, to accommodate the understanding of the common people it is appropriate for Scripture to say many things that are different in appearance and in regard to the surface meaning of the words from the absolute truth ... and so it seems that natural phenomena which are placed before our eyes by sensory 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.

We know that, by 1615, Galileo was convinced that he was on the verge of achieving a demonstration for the motion of the Earth, but he needed time. He sought to prevent the Church from condemning as heretical the claim that the Earth moves, when he was about to demonstrate that in fact the Earth does move. He expected that an argument from the phenomenon of the ocean tides would provide the necessary demonstration. He circulated a manuscript on this subject in late 1615 and early 1616, and the argument appears in the final section of his Dialogue Concerning the Two Chief World Systems, published in 1632.

Shared principles
So, in 1615 and 1616, neither Galileo nor the Inquisition thought there was a demonstration for the motion of the Earth: Galileo expected, indeed anticipated, such a demonstration; the Inquisition did not. Galileo’s principles were shared by his opponents in the Inquisition, although they reached a different conclusion when they examined the particular case of Copernican astronomy. The theological consultants of the Inquisition were asked to evaluate the claims of Copernican astronomy. They issued their report to the cardinals of the Inquisition in February 1616. The report concluded that the claim that the Sun was immobile and at the centre of the universe was:

... foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture, according to the literal meaning of the words and according to the common interpretation and understanding of the Holy Fathers and the doctors of theology.

The theologians also concluded that the claim that the Earth moves was also foolish and absurd in philosophy and ‘in regard to theological truth it is at least erroneous in faith’.

Science and Scripture: complementary
It is important to note that the first part of each of these two conclusions reached by the theologians is that Copernican astronomy is ‘false and absurd’ philosophically, that is, scientifically. Why should the theological experts of the Inquisition care whether Copernican astronomy is false scientifically? The theologians of the Inquisition were committed to the complementarity between science and Scripture. If a proposed scientific proposition is false, Scripture cannot be in agreement with it, since the Bible cannot affirm as true that which reason knows to be false. Furthermore, in reaching the conclusion that Copernican astronomy contradicts the Bible, the theologians accepted as incontrovertibly true a particular geocentric cosmology, and, on the basis of such an acceptance, they insisted that the Bible be read in a certain way.

Thus, in part, they subordinated scriptural interpretation to a physical theory. They proceeded in this manner because, like Galileo, they were convinced that the Bible contained scientific truths and that, on the basis of what is known to be true in the natural sciences, one could discover the same truth in related biblical passages. They did not argue – as most commentators mistakenly think – that the proposition was false scientifically because it contradicted the Bible. In fact, their argument was just the opposite. Furthermore, just as some philosophers mistakenly concluded that Aristotelian physics and metaphysics depended on a geocentric cosmology, so some theologians feared that a rejection of Aristotle’s view that the Earth does not move would call into question all of Aristotelian philosophy, a philosophy upon which important elements of Catholic theology depended.

After the consulting theologians issued their report to the cardinals of the Inquisition, Cardinal Bellarmino, on instructions from Pope Paul V, ordered Galileo not to hold, teach, or defend the condemned propositions. Furthermore, the publication of Copernicus’ book was to be suspended until corrections could be made to it. The corrections eventually ordered by the Index of Forbidden Books involved changing those passages in which Copernicus claims that in fact the Earth moves to read that he simply supposed or hypothesised that the Earth moves. The distinction between speaking hypothetically and speaking absolutely, which Bellarmino had urged upon Galileo in Apri1 1615 as prudential advice, now served as the basis for the disciplinary decrees of the Inquisition and the Index of Forbidden Books.

No choice
In ordering Galileo not to hold or teach Copernican astronomy, the Inquisition did not think that it was requiring Galileo to choose between faith and science. Nor, in the absence of scientific knowledge for the motion of the Earth, would Galileo have thought that he was asked to make such a choice. Here it is important to remember that Galileo and the Inquisition thought that science was absolutely certain knowledge, guaranteed by rigorous demonstrations. Being convinced that the Earth moves is different from knowing that it moves.

The disciplinary decree of the Inquisition was unwise and imprudent; but, as I have already indicated, what the Inquisition did in 1616 was to subordinate the interpretation of certain passages of the Bible to a geocentric cosmology, a cosmology which would eventually be rejected. Such an action is just the opposite of the domination of science by religious faith!

In 1632, Galileo published his Dialogue Concerning the Two Chief World Systems, in which he supported the Copernican ‘world system’. As a result, Galileo was charged with disobeying the 1616 injunction not to defend Copernican astronomy. The Inquisition’s injunction, however ill-advised, only makes sense if we recognise that the Inquisition saw no possibility of a conflict between science and religion, both properly understood. In 1633, the Inquisition, to ensure Galileo’s obedience, required that he publicly and formally affirm that the Earth does not move. Galileo, however reluctantly, acquiesced. This meeting of the Inquisition in June 1633 was presided over by Pope Urban VIII and he formally approved the decision to make Galileo publicly recant his views.

Discipline, not dogma
Nevertheless, from beginning to end, the actions of the Inquisition were disciplinary, not dogmatic, although they were often based on the erroneous notion that it was heretical to claim that the Earth moves. Erroneous notions remain only notions; opinions of theologians are not the same as Christian doctrine: not in the seventeenth century, not even in the twenty-first century. The error the Church made in dealing with Galileo was an error in judgement; the Inquisition was wrong to discipline Galileo, but discipline is not dogma: even when the discipline is ordered directly by the pope. Surely the disciplinary acts of the Inquisition, especially in such a famous case as Galileo, serve a teaching role, in a broad, sociological sense of teaching, but from a theological point of view such acts ought not to be confused with formal doctrinal pronouncements.

The view that there has been a long history of warfare between science and religion really was nurtured in the nineteenth century, the great age of positivism, which saw modern science as the pinnacle of human thought. For the positivists, science was objective, inductive and experimental – and it was born in the great revolution of the seventeenth century when geniuses such as Galileo and Newton succeeded in overthrowing the heritage of Aristotle. Thus, the Inquisition’s treatment of Galileo was but one of the attempts to impede the inevitable progress of the human mind. The legend of Galileo’s persecution by the Inquisition became part of the larger story – also widely accepted – of the Scientific Revolution. The more one saw that Revolution in terms of the victory of the modern scientific method, a method, so it was claimed, which Galileo pioneered, the more it was easy to accept what had become the common wisdom of the Inquisition’s attempting to thwart scientific progress to protect the literal truth of the Bible. Such a view of the ‘Galileo Affair’ leads easily to the conclusion that science and religion are necessarily incompatible.

Ill-founded legend
An important source of the notion that the Galileo affair is a central chapter in a long history of warfare between science and religion can be found in the debates in the late nineteenth century over the reception of Darwin’s theory of evolution. Increasingly, this metaphor of warfare served as a principle in the modern world’s understanding of its own history and the legend of Galileo was important evidence for the purported truth of this interpretation. At the same time the legend has been held captive by this interpretation: so much so that, even today when we know how ill-founded the legend is, it remains difficult to reject it.

This is particularly true in the United States, where Andrew Dickson White’s History of the Warfare of Science with Theology in Christendom (1896) enshrined what has come to be a historical orthodoxy difficult to dislodge. White used the example of the ‘persecution’ of Galileo by the Inquisition as an ideological tool in his attack on the religious opponents of evolution. Since it was so obvious by the late nineteenth century that Galileo was right, it was useful to see him as the great champion of science against the forces of dogmatic religion. White’s account may sound a bit extreme; nevertheless, we should be able to recognise an affinity between it and the persisting legend of Galileo:

[Galileo’s] discoveries had clearly taken the Copernican theory out of the list of hypotheses, and had placed it before the world as a truth. Against him, then, the war was long and bitter. The supporters of what was called ‘sound learning’ declared his discoveries deceptions and his announcements blasphemy. Semi-scientific professors, endeavoring to curry favor with the church, attacked him with sham science; earnest preachers attacked him with perverted scripture; theologians, inquisitors, congregations of cardinals, and at least two popes dealt with him, and, as was supposed, silenced his impious doctrine forever...

The whole struggle to crush Galileo and to save him would be amusing were it not fraught with evil. There were intrigues and counter-intrigues, plots and counter-plots, lying and spying; and in the thickest of this seething, squabbling, screaming mass of priests, bishops, archbishops, and cardinals, appear two popes, Paul V and Urban VIII. It is most suggestive to see in the crisis of the church, at the tomb of the prince of the apostles, on the eve of the greatest errors in church policy the world has known, in all the intrigues and deliberations of these consecrated leaders of the church, no more evidence of the presence of the Holy Spirit than in the caucus of New York politicians.

The debate over papal infallibility, formally defined at the First Vatican Council in 1870, as well as liberal reaction to the Catholic Church’s condemnation of ‘modernism’, and the politics of the Italian Risorgimento only reinforced the skewed interpretation of the Galileo affair as a prime example of the hostility of the Catholic Church to reason and science. How, so it was alleged, could the Church proclaim its pontiff to be infallible when at least two popes affirmed as a matter of faith the false position that the Earth did not move?

It was the same ‘reactionary’ Church which condemned Galileo, which also opposed Italian unification and modern political and social movements, and was, accordingly, a great obstacle to the advancement of humanity. It is interesting that in current debates about whether human cloning should be prohibited the spectre of Galileo is invoked by those who argue for freedom of scientific research and cast those who wish to prohibit such research as modern-day inquisitors.

There is no evidence that when Galileo acceded to the Inquisition’s demand that he formally renounce the view that the Earth moves, he muttered under his breath, eppur si muove, ‘but still it moves’. There was a conflict between Galileo and the Inquisition, but it was a conflict between those who shared common first principles about the nature of scientific truth and the complementarity between science and religion. In the absence of scientific knowledge that the Earth moves, Galileo was required to affirm that it did not. However unwise it was to insist on such a requirement, the Inquisition did not ask Galileo to choose between science and faith.

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