Thursday, April 01, 2010

Galileo on the relation between science and religion

Galileo’s view of natural philosophy (science) is that it is the study of the book of nature,” “written in mathematical language” (Finocchiaro 2008, p. 183), as contrasted with theology, the study of the book of Holy Scripture and revelation.  Galileo endorses the idea that theology is the “queen” of the “subordinate sciences” (Finocchiaro 2008, p. 124), by which he means not that theology trumps science in any and all matters.  He distinguishes two senses of theology being “preeminent and worthy of the title of queen”: (1) That “whatever is taught in all the other sciences is found explained and demonstrated in it [theology] by means of more excellent methods and of more sublime principles,” [Note added 12/14/2012: which he rejects] and (2) That theology deals with the most important issues, “the loftiest divine contemplations” about “the gaining of eternal bliss,” but “does not come down to the lower and humbler speculations of the inferior sciences ... it does not bother with them inasmuch as they are irrelevant to salvation” [Note added 12/14/2012: which he affirms] (quotations from Finocchiaro 2008, pp. 124-125).  Where Holy Scripture makes reference to facts about nature, they may be open to allegorical interpretation rather than literal interpretation, unless their literal truth is somehow necessary to the account of “the gaining of eternal bliss.”

Galileo further distinguishes two types of claims about science:  (1) “propositions about nature which are truly demonstrated” and (2) “others which are simply taught” (Finocchiaro 2008, p. 126).  The role of the theologian with regard to the former category is “to show that they are not contrary to Holy Scripture,” e.g., by providing an interpretation of Holy Scripture compatible with the proposition; with regard to the latter, if it contradicts Holy Scripture, it must be considered false and demonstrations of the same sought (Finocchiaro 2008, p. 126).  Presumably, if in the course of attempting to demonstrate that a proposition in the second category is false, it is instead demonstrated to be true, it then must be considered to be part of the former category.  Galileo’s discussion allows that theological condemnation of a physical proposition may be acceptable if it is shown not to be conclusively demonstrated (Finnochiaro 2008, p. 126), rather than a more stringent standard that it must be conclusively demonstrated to be false, which, given his own lack of conclusive evidence for heliocentrism, could be considered a loophole allowing him to be hoist with his own petard.

Galileo also distinguishes between what is apparent to experts vs. the layman (Finnochiaro 2008, p. 131), denying that popular consensus is a measure of truth, but regarding that this distinction is what lies behind claims made in Holy Scripture about physical propositions that are not literally true.  With regard to the theological expertise of the Church Fathers, their consensus on a physical proposition is not sufficient to make it an article of faith unless such consensus is upon “conclusions which the Fathers discussed and inspected with great diligence and debated on both sides of the issue and for which they then all agreed to reject one side and hold the other” (Finnochiaro 2008, p. 133).  Or, in a contemporary (for Galileo) context, the theologians of the day could have a comparably weighted position on claims about nature if they “first hear the experiments, observations, reasons, and demonstrations of philosophers and astronomers on both sides of the question, and then they would be able to determine with certainty whatever divine inspiration will communicate to them” (Finnochiaro 2008, p. 135).

Galileo’s conception of science that leads him to take this position appears to be drawn from what Peter Dear (1990, p. 664), drawing upon Thomas Kuhn (1977), calls “the quantitative, ‘classical’ mathematical sciences” or the “mixed mathematical sciences,” identifying this as a predominantly Catholic conception of science, as contrasted with experimental science developed in Protestant England.  The former conception is one in which laws of nature can be recognized through idealized thought experiments based on limited (or no) actual observations, but demonstrated conclusively by means of rational argument.  This seems to be the general mode of Galileo’s work.  Dear argues that this notion of natural law allows for a conception of the “ordinary course of nature” which can be violated by an observed miraculous event, which comports with a Catholic view that miracles continue to occur in the world.

By contrast, the experimentalist views of Francis Bacon and Robert Boyle involve inductively inferring natural laws on the basis of observations, in which case observing something to occur makes it part of nature that must be accounted for in the generalized law--a view under which a miracle seems to be ruled out at the outset, which was not a problem for Protestants who considered the “age of miracles” to be over (Dear 1990, pp. 682-683).  Dear argues that for the British experimentalists, authentication of an experimental result was in some ways like the authentication of a miracle for the Catholics--requiring appropriately trustworthy observations--but that instead of verifying a violation of the “ordinary course of nature,” it verified what the “ordinary course of nature” itself was (Dear 1990, p. 680).  Where the Catholics like Galileo and Pascal derived conclusions about particulars from universal laws recognized by observation, reasoning, and mathematical demonstration, the Protestants like Bacon and Boyle constructed universal laws by inductive generalization from observations of particulars, and were notably critical of failing to perform a sufficient number of experiments before coming to conclusions (McMullin 1990, p. 821), and put forth standards for hypotheses and experimental method (McMullin 1990, p. 823; Shapin & Schaffer 1985, pp. 25ff & pp. 56-59).  The English experimentalist tradition, arising at a time of political and religious confusion after the English Civil War and the collapse of the English state church, was perhaps an attempt to establish an independent authority for science.  By the 19th century, there were explicit (and successful) attempts to separate science from religious authority and create a professionalized class of scientists (e.g., as Gieryn 1983, pp. 784-787 writes about John Tyndall).

The English experimentalists followed the medieval scholastics (Pasnau, forthcoming) in adopting a notion of “moral certainty” for “the highest degree of probabilistic assurance” for conclusions adopted from experiments (Shapin 1994, pp. 208-209).  This falls short of the Aristotelian conception of knowledge, yet is stronger than mere opinion.  They also placed importance on public demonstration in front of appropriately knowledgeable witnesses--with both the credibility of experimenter and witness being relevant to the credibility of the result.  Where on Galileo’s conception expertise appears to be primarily a function of possessing rational faculties and knowledge, on the experimentalist account there is importance to skill in application of method and to the moral trustworthiness of the participants as a factor in vouching for the observational results.  In the Galilean approach, trustworthiness appears to be less relevant as a consequence of actual observation being less relevant--though Galileo does, from time to time, make remarks about observations refuting Aristotle, e.g., in “Two New Sciences” where he criticizes Aristotle’s claims about falling bodies (Finnochiaro 2008, pp. 301, 303).

The classic Aristotelian picture of science is similar to the Galilean approach, in that observation and data collection is done for the purpose of recognizing first principles and deriving demonstrations by reason from those first principles.  What constitutes knowledge is what can be known conclusively from such first principles and what is derived by necessary connection from them; whatever doesn’t meet that standard is mere opinion (Posterior Analytics, Book I, Ch. 33; McKeon 1941, p. 156).  The Aristotelian picture doesn’t include any particular deference to theology; any discipline could could potentially yield knowledge so long as there were recognizable first principles. The role of observation isn’t to come up with fallible inductive generalizations, but to recognize identifiable universal and necessary features from their particular instantiations (Lennox 2006).  This discussion is all about theoretical knowledge (episteme) rather than practical knowledge (tekne), the latter of which is about contingent facts about everyday things that can change.  Richard Parry (2007) points out an apparent tension in Aristotle between knowledge of mathematics and knowledge of the natural world on account of his statement that “the minute accuracy of mathematics is not to be demanded in all cases, but only in the case of things which have no matter.  Hence its method is not that of natural science; for presumably the whole of nature has matter” (Metaphysics, Book II, Ch. 3, McKeon 1941, p. 715).

The Galilean picture differs from the Aristotelian in its greater use of mathematics (geometry)--McMullin writes that Galileo had “a mathematicism ... more radical than Plato’s” (1990, pp. 822-823) and by its inclusion of the second book, that of revelation and Holy Scripture, as a source of knowledge.  But while the second book is one which can trump mere opinion--anything that isn’t conclusively demonstrated and thus fails to meet Aristotle’s understanding of knowledge--it must be held compatible with anything that does meet those standards.

  • Peter Dear (1990) “Miracles, Experiments, and the Ordinary Course of Nature,” ISIS 81:663-683.
  • Maurice A. Finocchiaro, editor/translator (2008) The Essential Galileo.  Indianapolis: Hackett Publishing Company.
  • Thomas Gieryn (1983) “Boundary Work and the Demarcation of Science from Non-Science: Strains and Interests in Professional Ideologies of Scientists,” American Sociological Review 48(6, December):781-795.
  • Thomas Kuhn (1957) The Copernican Revolution: Planetary Astronomy in the Development of Western Thought.  Cambridge, Mass.: Harvard University Press.
  • Thomas Kuhn (1977) The Essential Tension.  Chicago: The University of Chicago Press.
    Lennox, James (2006) “Aristotle’s Biology,” Stanford Encyclopedia of Philosophy, online at, accessed March 18, 2010.
  • Richard McKeon (1941) The Basic Works of Aristotle. New York: Random House.
  • Ernan McMullin (1990) “The Development of Philosophy of Science 1600-1900,” in Olby et al. (1990), pp. 816-837.
  • R.C. Olby, G.N. Cantor, J.R.R. Christie, and M.J.S. Hodge (1990) Companion to the History of Science.  London: Routledge.
  • Parry, Richard (2007) “Episteme and Techne,” Stanford Encyclopedia of Philosophy, online at, accessed March 18, 2010.
  • Robert Pasnau (forthcoming) “Medieval Social Epistemology: Scienta for Mere Mortals,” Episteme, forthcoming special issue on history of social epistemology.  Online at, accessed March 18, 2010. 
  • Steven Shapin and Simon Schaffer (1985) Leviathan and the Air Pump: Hobbes, Boyle, and the Experimental Life.  Princeton, N.J.: Princeton University Press.
  • Steven Shapin (1994) A Social History of Truth: Civility and Science in Seventeenth-Century England. Chicago: The University of Chicago Press.
[The above is slightly modified from one of my answers on a midterm exam.  My professor observed that another consideration on the difference between Catholic and Protestant natural philosophers is that theological voluntarism, more prevalent among Protestants, can suggest that laws of nature are opaque to human beings except through inductive experience.  NOTE ADDED 13 April 2010: After reading a couple of chapters of Margaret Osler's Divine Will and the Mechanical Philosophy: Gassendi and Descartes on Contingency and Necessity in the Created World (2005, Cambridge University Press), I'd add Pierre Gassendi to the experimentalist/inductivist side of the ledger, despite his being a Catholic--he was a theological voluntarist.]


Rain said...

Erratum! No, Galileo actually said that theology was NOT the "queen of the sciences." See, for example, Finocciaro (2010), Defending Copernicus and Galileo (eBook): "Galileo next undertakes an explicit criticism of theological authority. He argues that theology is not the queen of the sciences because it is obvious that its principles do not provide the logical foundations of the knowledge formulated in other sciences, the way that, for example, geometry does for surveying (324-325)."

Jim Lippard said...

Rain: I've added clarifying notes. Galileo rejected the premise in the sense you point out (sense 1 in my description), but affirmed it in the second sense. He did not say "theology is not the queen of the sciences" and was at pains to find a way to affirm that it is, even as he limited the scope of that statement.