Who was Galileo Galilei? An essay biography of Galileo

by Wade Rowland, author of Galileo’s Mistake: A New Look at the Epic Confrontation between Galileo and the Church

As a hero of science, Galileo Galilei long ago achieved secular sainthood. A finger is preserved like a holy relic in the museum of science in Florence, a vertebra at the University of Padua. His lavish tomb in Florence’s magnificent basilica of Santa Croce has been newly buffed and polished by an officially contrite Church. But he continues to be admired for all the wrong reasons. One can imagine him, wherever he has been ensconced in death, fulminating as he did in life, appalled at the stupidity of the world of conventional wisdom and its inability to see the facts before its eyes.

As a man of no small ego, and a touch paranoid to boot, he would doubtless enjoy of the veneration in which he is held as astronomer and martyr to reason and science, victim of religious dogmatism and anti-intellectualism. But he would be greatly disturbed by the simple-minded version of his travails that has come down to us through three and a half centuries of myth-making and propaganda. He would want to insist that his argument with the Church was of far, far greater significance than a squabble over whether or not the earth moves, as most of us now suppose it was. The Copernican question had in fact been largely settled in the minds of the better informed Church leaders, including the pope and his chief theologian – not to mention the brilliant Jesuit mathematicians and astronomers of the Collegeo Romano – long before Galileo’s epic confrontation with Rome came to a head.

In the matter of his notorious trial by the Holy Office in 1633, he conceded his error and publicly – and sincerely – demonstrated his contrition. He had, as the Church charged, no conclusive grounds for claiming that the Copernican hypothesis was fact, and it had been a matter of serious insubordination for him to disobey a direct papal order not to go about behaving as if he did. As a deeply committed Catholic and the beneficiary of ecclesiastical favours, he was, after all, obliged to play by the rules. But to this day his admirers stubbornly refuse to accept him at his word, preferring in a bizarre twist of logic to see him as a moral weakling, cowed by threats of the rack, or, worse, a liar and perjurer who falsely confessed before God in order to save his mortal skin.

He was none of these things. (Nor, as he knew, were threats of torture more than an antiquated procedural formality – no threat at all.) He was a man captivated by his discovery that laws of mechanical motion could be derived from direct observation of the world, and then expressed in elegant mathematical formulae. The scales had fallen from his eyes and he could see with ecstatic clarity that the world was in some very real way composed of number.

“Philosophy is written in this grand book the universe, which stands continually open to our gaze,” Galileo said in The Assayer, “but the book cannot be understood unless one first learns to comprehend the language and to read the alphabet in which it is composed. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures, without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth.” He had unlocked the logic of the scientific method, and concluded that its power was limitless, that with time and resources it was possible in principle for human reason to know everything there is to know – to know what God knows.

This was his tragic blindness and it was for this that the Church attacked him. Galileo believed that there is a single and unique explanation to all natural phenomena, one that can be understood through observation and reason and which makes all other explanations wrong. The Church insisted that science, though useful, was only one route to knowledge about the world.

With Plato and Aristotle, Church authorities insisted that number was not inherent in the world, but was projected upon it by humans: laws of science were not discovered but invented. The elaborate mathematical formulae of the Copernican hypothesis (scarcely less baffling than the Ptolemaic system it replaced) were not descriptions of reality, but maps or models of reality. It was a serious error, the Church said, a prideful error, to mistake the map for the territory. There would always be a gap between science’s models and the reality they represent, one that could not be bridged by human reason. Ultimate knowledge was accessible only through the spirit, or the revealed wisdom of Scripture.

Today, philosophers of science and scientists themselves make the same point, using the language of recursiveness, and of Gödel’s uncertainty theorems and Heisenberg’s indeterminacy principle. Science in our time has established to its own satisfaction that its access to knowledge is limited – in principle – to some condition forever short of completeness.

Or, as Urban VIII repeatedly warned Galileo, it is an error to “impose necessity” on God. We have evidence of the strength of Urban VIII’s conviction on this point from the Florentine ambassador to Rome, in his record of a papal audience just prior to Galileo’s trial:

“He [Urban VIII] added that Signor Galileo had been his friend, that often they had dined familiarly at the same table, and that he was sorry to subject him to these annoyances, but that it was a matter of faith and religion. I think I remarked that when he [Galileo] was heard he would be able, without difficulty, to give all explanations requested. He answered that he will be examined in due time but that there is an argument to which they have never yet given an answer, and that is that God is all-powerful, and, if He is, why should we try to necessitate Him? I said that I did not know how to speak on those matters, but that I thought I had heard Galileo saying that he was willing not to believe in the motion of the Earth, but that as God could make the world in a thousand ways, so it could not be denied that He could have made it in this way too. He grew angry and replied that we should not impose necessity upon the Lord Almighty; and, as I saw him working himself up to a fury, I avoided saying more that might have hurt Galileo.”

In this and other contemporary records it is clear that the Church’s overriding concern was the preemption by science of all claims to authentic knowledge. Modern accounts of the martyrdom of Galileo also frequently focus on the well-worn fable of the Church’s rejection of Copernicanism because it conflicted with Scripture. Certain references in the Bible seemed to indicate that the earth was immobile, and that the sun revolves around the earth. Galileo is supposed to have come to grief for the following reason: in insisting on the truth of Copernicanism, he was undermining the accuracy of Scripture, upon which the Church based its authority. To the extent that this was an issue in Galileo’s confrontation with Rome (and it was certainly a minor point), we can see from our current perspective that, once again, Galileo was in error. Because, as the Church saw it and as we can see today, the issue was not the simple matter of the place of the sun and earth in the solar system, but the much more profound question of how to verify knowledge.

To begin with, the Vatican’s chief theologian, Cardinal Roberto Bellarmine, clearly stated that when Scripture seems to contradict well-established empirical fact, then Scripture must be re-interpreted to conform to fact: “[If Copernicanism were verified] it would be necessary to use careful consideration in explaining the Scriptures that seemed contrary, and we should rather have to say that we do not understand them than to say that something is false which had been proven.” Galileo seized on this point to argue for the primacy of scientific knowledge. The kernel of his argument is this: the Bible is the word of God and as such cannot err. However, interpreters of the Bible are human, and thus make mistakes of interpretation. Even the pope may make such mistakes, in matters that are not directly related to faith, such as the movements of the planets.

“Certainly,” Galileo says, “no one doubts that the Supreme Pontiff has always an absolute power to approve or condemn, but it is not in the power of any created being to make things true or false, for this belongs to their own nature and to the fact.” Nature is also revelation of God, he continues, but nature is its own interpreter, and never errs: “For this reason it appears that nothing physical which sense-experience sets before our eyes, or which necessary demonstrations prove to us, ought to be called in question, much less condemned, upon the testimony of Biblical passagesŠ”.

Remembering that Galileo also argued that science can know everything, this becomes a very serious challenge to Church authority across the gamut of knowledge. Naturally, the Church demurred.

Those who have even a smattering of philosophy will recognize in Galileo’s position as something called “naïve realism.” They will know that it has no legitimate claim to being a coherent view of the nature of reality, having been discredited by a long line of philosophers stretching back to the eighteenth century. As for Galileo’s notion that empirical knowledge – that “which sense-experience sets before our eyes” – is definitive and unchallengeable, modern science from neurophysiology to information and automata theory knows otherwise: all scientific knowledge contains important, sometimes critical, elements of subjectivity.

Nature is in fact not its own interpreter. We all see the world through spectacles of human construction, and from time to time we change glasses and find that we have an entirely new and different view of things. These shifts, when they occur in science, are called scientific revolutions, and it is impossible, ever, to say we have seen the last of them.

We should admire Galileo for what he was: an inspired but fallible progenitor of the scientific enterprise, understandably bedazzled by its power. We should at the same time recognize the important truths championed by his adversaries in the Church, who drew from a much deeper well of philosophical experience. Not the least of those truths is that moral and natural philosophy cannot survive as separate and exclusive fields of knowledge without each running the risk of becoming a grotesque and dangerous parody of itself.