Galileo contra Theological Voluntarism

Dialogue Concerning the Two Chief World Systems

Galileo Galilei

(Image from Wikipedia)

John Heilbron's biography of Galileo is now moving toward the crisis of this scientist's life, Pope Urban VIII's reaction to the publication in 1632 of the Dialogue Concerning the Two Chief World Systems, in which Galileo offers Copernicanism as an explanation for the tides, though his argument here was to prove erroneous. The Pope did not object to Galileo's book so much as to Galileo's obvious conviction that Copernicanism was true. While the Pope had allowed for Galileo to advocate the use of Copernican theory as a device for calculating the apparent motions of the heavens, the theory could not be defended as literally, physically true. Actually, the Pope went a bit further than that, insisting that God, in His omnipotence and infinite wisdom, may in fact have used any of a potentially infinite possible structures for the cosmic mechanism hidden behind the facade that we empirically perceive with our eyes. Galileo seems not to have liked the argument, but he put the Pope's position into the mouth of one of the three characters in his Dialogue:

As to the discourses we have held, and especially this last one concerning the reasons for the ebbing and flowing of the ocean, I am really not entirely convinced; but from such feeble ideas of the matter as I have formed, I admit that your thoughts seem to me more ingenious than many others I have heard. I do not therefore consider them true and conclusive; indeed, keeping always before my mind's eye a most solid doctrine that I once heard from a most eminent and learned person, and before which one must fall silent, I know that if asked whether God in His infinite power and wisdom could have conferred upon the watery element its observed reciprocating motion using some other means than moving its containing vessels, both of you would reply that He could have, and that He would have known how to do this in many ways which are unthinkable to our minds. From this I forthwith conclude that, this being so, it would be excessive boldness for anyone to limit and restrict the Divine power and wisdom to some particular fancy of his own. (Galileo Galilei, Dialogue Concerning the Two Chief World Systems, Ptolemaic & Copernican, translated by Stillman Drake, University of California Press, 1967, page 464)

This was the Pope's position, a variant on theological voluntarism, which has a rather long history in Christianity. Heilbron suggests that the Pope wanted Galileo to offer as Galileo's own position, and in Galileo's own words, something like the following:

The comedy has ended. Italian honor and the reputation of the Holy Church are saved from the calumniators who would destroy our faith. But do not deduce from this happy outcome, gentle reader, that you are free to assert the absolute truth of a physical system even if the arguments in its favor seem unanswerable. For as I learned long ago from His Holiness, any such assertion would derogate from the Omnipotence of God, who in His wisdom and power can do or make anything that does not involve Him in a contradiction. The argument of His Holiness is in fact and logic unanswerable. A true Christian must bend the knee and fall silent before it. (Heilbron, Galileo, 2010, pages 303-304)

This variant of theological voluntarism is not the most radical sort, for it still presupposes a rational deity, one who does not contradict himself -- which is, I have read, different from Islamic voluntarism, which does not even limit Allah rationally to the principle of noncontradiction, but that's neither here nor there in Galileo's case. But even this limited voluntarism seems not to Galileo's liking, for he did not write these words and express them as his own position. Instead, he expressed the Pope's view as the view of the character named Simplicio, the simpleton in the Dialogue who supports the traditional, earth-centered cosmos that was a synthesis of Plato and Aristotle (even though the Pope's view is not, strictly considered, even Simplicio's position). But why didn't Galileo bend his knee on this point and express as his own the Pope's view on theological voluntarism? Heilbron suggests:

Had Galileo written such words, philosophers, mathematicians, and astrologers whose theories implicitly limited God's past and future actions would find themselves opposed to the greatest mathematician in Italy, and perhaps the world. But Galileo could not speak Urban's words. That would have amounted to a denial of his mission. (Heilbron, Galileo, 2010, page 304)

What was this mission? To defend the truth of Copernicanism! For Galileo, Copernicanism was the physically correct system to hold, for both rational and empirical reasons. Galileo was, implicitly anyway, opposed to theological voluntarism. But why opposed? Did he consider as unworthy the belief that God would offer a cosmic facade that misleads scientists to the conviction that one cosmic system is preferable to another, that one cosmic system is physically true?

I do not know what Galileo thought, but that would appear to me to be a reasonable objection to even Pope Urban VIII's limited theological voluntarism, for to concede that a rational God might nevertheless deceive our sense perceptions on the structure of the world is, arguably, inconsistent.

Such a voluntarist view is the sort that Hans Blumenberg, in his magnum opus, The Legitimacy of the Modern Age, called a variant on Gnosticism, perhaps the oldest theological heresy, and hence constituting an irony of history, if anything should, that the Pope would be advocating it against the 'heresy' of Copernicanism.