Introduction
In January 2008, for the opening of the academic year, the directorship of the Sapienza University, the oldest of Rome's four state universities (founded in 1303), had invited an eminent speaker: Pope Benedict XVI[1], no less. However the organisers of the day had miscalculated the symbolic charge of such an invitation. Soon after the program was published, Professor Marcello Cini[2] protested the presence of a religious figure in the scientific realm: in an open letter to the rector of the University, he stated that religion had nothing to do with science, a fact made obvious by cases such as Darwin's and Galileo's. The letter called on whomsoever championed the sciences to join him in protest against the projected invitation. Whereupon it was discovered that some twenty years earlier, the pope to be had defended in a talk the ecclesiastical court that had tried Galileo, which was immediately construed as undeniable evidence of the Pope's anti-science credentials. A letter of protest was accordingly signed by 67 members of the faculty, the Sapenza's administrative buildings were occupied by far left students and in the end Benedict XVI cancelled, postponing the occasion. However, in spite of spontaneous demonstrations sympathetic to the Pope (including some tens of thousands of demonstrators showing up on St Peter's Square three days after the address' set date), his lecture never took place.
This episode is a measure of the extent to which, at the beginning of the 21st century, the relation between science and religion can still exercise tempers; neither should anybody be surprised to find science's self-appointed champions harking back to the Galileo affair. The great early 17th century Florentine mathematician is best known as the tragic pioneer of modern science. His championing a heliocentric cosmology[3], as set forth by Copernicus[4], against the Ptolemaic[5] tradition's geocentric system[6] adopted at the time by the Church had become the symbol of the struggle between a rationalist and free science to one side and a dogmatic and therefore irrational Church to the other. Even before his death Galileo was considered a hero and very soon a “martyr” to science. Legend consolidated around his figure; aphorisms that he never uttered are ascribed to him, indeed he is credited with discoveries he never made. Thus, to a section of those who challenged the role of religious authorities in the realm of science and in academic institutions, Galileo had, to all intents and purposes, become some sort of secular “saint”.
Now, at the end of the 19th century critical historiography undertook a demystification of Galileo, a most unwelcome trend for Italian nationalist historiography but which got the ear of Catholic apologists[7]. If Galileo was not the man painted in legends, this could give a whole new complexion to the image of the church in the affair. In the event, this apologetic driven research work unearthed sources that could dent Galileo's image and method in defence of Heliocentrism. Ever since, two versions of the “Galileo affair” have confronted each other: to one side the perpetuation of the heroic myth, which found a powerful exponent in Bertold Brecht[8] with his 1939 play Das Leben des Galilei; to the other the Catholic apologetic tradition to which the future Pope's defense of Galileo's judges undoubtedly belongs.
It is difficult in the presence of these two readings to take a position on the Galileo affair without being suspected of siding with one or the other camp. Because of the symbolic value the affair still caries, the subject is well suited to assessing past and present relations between science and religion, not just because Galileo has left us his own assessment of these relations but, more interestingly, because, for him, this was not a confrontation between science and religion but between two scientific theories, namely heliocentrism and geocentrism. Thus this affair is a case in point to appreciate what goes on when two incompatible systems of thought[9] face each other. After calling to mind essential factual data, we will explore the vexed issue of science's clash with religion (or is it science with science?), prior to the exposition of a third possible reading stemming from the philosophy of science[10]. It will help us understand why Galileo's argumentation did not convince his contemporaries and what this affair tells us about ongoing debates.
