I have taught excerpts from a few of Galileo’s works–Starry Messenger, The Assayer, Dialogue Concerning the Two Chief World Systems, Dialogues Concerning Two New Sciences–but the best historical insights and discussions come from a close reading of what can only be called Galileo’s primary theological work, the Letter to the Grand Duchess Christina.
Critical reading and discussion of Galileo and his works, if done from an historically informed perspective, is one of the most profitable correctives to one’s knowledge of the history of science and religion in the pre-Victorian era. As Tim O’Neill wrote in his review of God’s Philosophers: How the Medieval World Laid the Foundations of Modern Science, no version of the “hysterical myths” of a Christian Dark Ages is complete without wheeling out poor Galileo to demonstrate the supposed malicious suppression of scientific knowledge by raving, superstitious cardinals and popes in the Catholic Church. The facts, however, about Galileo, the cardinals, the popes, and the connections between the endeavors of empirical science, its philosophical foundations, and the concerns of religion, as actually played out in early seventeenth-century Europe, are far more complex and interesting than “The Myth.”
In his 2000 book When Science Meets Religion: Enemies, Strangers, or Partners?, physicist and philosopher Ian Barbour describes a four-fold model for classifying ways to relate science and religion: Conflict, Independence, Dialogue, and Integration. “The Myth” has grown weed-like from late nineteenth century polemicists creating and promulgating the “conflict” thesis, the view that science and religion (Christianity) are inevitably at cultural and intellectual war. Despite the fact that this thesis has been long repudiated in academia by the research of actual and competent historians, it persists in the subcultures of armchair Internet polemicists and history-scorning niches of academia itself.
But historical misinformation about Galileo is not limited to axe-grinders. Ignorance about how the great minds in the medieval period advanced the study of nature and the erection of textbook heroes of the Scientific Revolution like Galileo conspire to spread misinformation about who discovered or theorized what and when. Examples abound. From the Wikipedia article on The Assayer linked above, the opening sentence declares that Galileo in this work “first broach[ed] the idea that the book of nature is to be read with mathematical tools rather than those of scholastic philosophy.” No, Wiki friends, Galileo cannot be given credit for first theorizing the connection between physics and mathematics. This insight goes back at least 300 hundred years prior to Galileo, to the fourteenth century. James Hannam quotes one of the “Merton Scholars,” Thomas Bradwardine, in God’s Philosophers,
[Mathematics] is the revealer of every genuine truth (…) whoever then has the effrontery to pursue physics while neglecting mathematics should know from the start that he will never make his entry through the portals of wisdom. (God’s Philosophers, 176, quoted in O’Neill)
Compare the relatively sparse Wikipedia entry for Bradwardine and this group of thinkers, the “Merton Scholars” or “Oxford Calculators.”
And with that incredibly lengthy introduction thankfully behind us, let’s turn to our Core Text outline and get to some key points about Galileo’s Letter to the Grand Duchess Christina…
Heliocentrism. The Letter purports to defend the Copernican model of the universe against the reigning geocentric model. You should be able to reconstruct these two models and understand the empirical evidence for them at the time.
Truth. It should go without saying, but these days, one can’t. Mind the distinction between the nature of truths and the knowledge of truths. Galileo argues from the obvious position (and assumes his readers will, too) that the nature of truths is absolute, i.e., nonrelative, while one’s knowledge of any given truth is fallible. (This is not the time to enter into the argument, but the view that the nature of truths is relative–a view I’ve often heard in the classroom asserted as though it were an obvious fact–suffers from the self-refuting implication that there is one truth which is nonrelative, viz., that truth is relative.) One possible source of the disagreement between Galileo and his opponents is the nature and domain of two reports: those from a sacred text and those from sense observation. Does Galileo regard these sources as equally truthful? As equally reliable? If they conflict with each other on some specific matter, how does he think the disagreement should be resolved?
Galileo marshals the Church Fathers and theologians of his own time to support his case. This should matter.
A significant portion of the Letter uses the tools of hermeneutics. “What’s that?” Exactly. The four rules for interpreting Scripture formulated by Benito Pereira, S.J., likely informed Galileo’s approach, so you should familiarize yourself with them to gain insights into Galileo’s interpretation of the Bible.
The concept of accommodation is extremely important to understand how Galileo interprets scriptural texts that refer to empirical phenomena and the natural world.
The hermeneutical climax of the Letter is Galileo’s interpretation of a miraculous event described in the 10th chapter of the book of Joshua in the Hebrew Bible. You should familiarize yourself with this text independently of Galileo’s quotations.
Galileo’s self-presentation in the opening paragraphs of the Letter should give you some indication why he sometimes rubbed people the wrong way.
“Natural philosophy” is another name for ‘science’ or ‘physics’, but it is not reducible to the empirical sciences. It recognizes, wrestles with, and often explicitly integrates its philosophical foundations in logic, metaphysics, and epistemology.
The Myth. Using Barbour’s four-fold model for describing how science and religion relate to each other, you should try to classify Galileo’s position as developed in the Letter. Does Galileo adopt one of the models consistently, or does he move among more than one of them?
Galileo’s relationship with the Church. For much of his career, Galileo enjoyed the favor and patronage of many leaders and clerics in the Church. He worked out key elements of the argument in the Letter earlier in correspondence with these friends, notably Benedetto Castelli. See Maurice Finocchiario’s The Galileo Affair for key materials to appreciate this background.
The Trial. It is helpful to know exactly what the charges were against Galileo that led to his prosecution by the Inquisition in 1633, and the evidence for those charges. Though the Church operated as an arm of civil authority, it is helpful to distinguish between the civil and religious censures and penalties actually enjoined on Galileo.