Galileo and the Causes

  • Peter Machamer
Part of the The University of Western Ontario Series in Philosophy of Science book series (WONS, volume 14)


The literature on Galileo’s methodology, or, if you like, his philosophy of science, is replete with reiteration of dichotomous terms, attempting to characterize Galileo’s work, necessarily or for the most part, as an instance, of a type. The terms ‘Patonism/Aristotelianism,’ ‘Mathematical/Experimental, ‘Rationalist/Empiricist’ have been used to describe Galileo’s work. What I hope to do in this essay is to provide a way of looking at Galileo which will undercut the force of such dichotomies and which at the same time will be more faithful to the 16th- and early 17th-century traditions of methodological discussion. I hope to make plausible the claim that Galileo is in a tradition, but one which has not been sufficiently recognized and has only begun to be studied. The tradition is that of the mixed sciences, which is itself a tradition blending mathematics and physics (or natural philosophy), blending Platonic (or neo-Platonic) and Aristotelian elements, blending reason and observation. It is this tradition I shall argue that Galileo takes on from the late 16th-century thinkers and which can be seen in all his works, even in the much studied Discorsi. Indeed, in Section II of this essay I shall concentrate my analysis almost wholly upon the Discorsi as published, assuming that if I can make my case plausible for that work the rest of the Galilean corpus will come into line also.1


Causal Principle Mathematical Demonstration Causal Term Causal Context Causal Language 
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  1. 2.
    Galileo Two New Sciences (transl. and introduced by Stillman Drake), University of Wisconsin, Madison, 1974, p. 154, footnote 12.Google Scholar
  2. 3.
    Wallace’s discussion is in his Causality and Scientific Explanation, Vol. I (University of Michigan, Ann Arbor, 1972), pp. 176f. Wallace does discuss some important aspects of Galileo’s demonstrations in his article ‘Galileo and Reasoning Ex Suppositione: The Methodology of Two New Science’ in Boston Studies in the Philosophy of Science, Vol. XXXII (Proceedings of the Philosophy of Science Association 1974), (ed. by R. S. Cohen et al.), Reidei, Dordrecht and Boston, 1976, p. 79.Google Scholar
  3. 4.
    There is a cryptic footnote in Santillana’s edition of Dialogo (Dialogue on the Great World Systems, Salusbury translation, University of Chicago Press, Chicago, 1953; p. 112) where in an apparently irrelevant context he cites a distinction between ‘reason’ and ‘cause’ asserted to have been made by Bruno in his De la Causa and remarks that Galileo was not unaware of this important distinction. The distinction actually seems to be that between ‘cause’ and ‘principle,’ which even in the 16th-century was an opaque distinction, though Bruno does draw it. In general, ‘principle’ — as in ‘first principle’ — is used to describe a causal or demonstrative principle.Google Scholar
  4. 5.
    A similar line is argued by J. A. Bennett in his ‘Christopher Wren: Astronomy, Architecture, and the Mathematical Sciences’ J. Hist. Astron. 6 (1974), 149–84. Bennett briefly discusses the tradition in England and argues that Wren is in it.Google Scholar
  5. 6.
    J. E. McGuire, ‘Active Principles and Neo Platonism: Newton and the Corpus Hermeticurm’ in Robert S. Westman and J. E. McGuire, Hermeticism and the Scientific Revolution, (William Andrews Clark Memorial Library, Los Angeles, 1977), pp. 95–142.Google Scholar
  6. 7.
    It is this tradition of the Mathematical sciences that J. A. Bennett, op. cit., pp. 149–52, calls ‘Vitruvian’ and which he characterizes as holding that mathematics was the only source of certainty in the natural world and that it was useful and relevant to practical pursuits. This characterization, as far as it goes, seems to fit Italian as well as English thinkers of the time.Google Scholar
  7. 8.
    This aspect of Galileo’s career has been studied by Thomas Settle and it is to him that I am indebted for this connection. Galileo’s work with Ricci and his knowledge of the tradition is discussed in Settle’s paper ‘Ostillio Ricci, A Bridge Between Alberti and Galileo’, Actes du XIIe Congres International D’Histoire des Sciences, Paris, 1968, Vol. IIIB (Paris 1971), pp. 121–26. During the workshop connected with this volume this side of Galileo’s heritage and its importance was again pointed out to me by Tom and specifically he mentioned Galileo’s teaching of perspective.Google Scholar
  8. 9.
    The works referred to are William Wallace’s paper in this volume, A. C. Crombie’s ‘Sources of Galileo’s Early Natural Philosophy’ in M. L. Righini Bonelli and William R. Shea (eds.), Reason, Experiment, and Mysticism in the Scientific Revolution, (Science History Publications, New York, 1975), pp. 157–76Google Scholar
  9. 9a.
    Paolo Galluzzi, ‘II “platonissmo” del trado cinguecento e la filosofìa de Galileo’, in Paola Zambelli (ed.), Ricerche sulla cultura dell’Italia moderna (Editori Laterza, 1973), pp. 39–79. I owe Winifred Wisan thanks for referring me to this last, excellent article.Google Scholar
  10. 12.
    In his very interesting and helpful article, Gallucci, op. cit., points out that Barozzi and Bianci held the view that mathematical demonstration proceeds through formal and material causes. These philosophers he takes to be, at least indirectly, influences upon Galileo.Google Scholar
  11. 14.
    Raymond Frederette pointed out to me one seemingly glaring exception to my expectations. In his last version of De Motu, Galileo clearly rejects the theory that lightness is the cause of a body’s motion upwards. He claims that those who have held this view did so because they were unable to find an external cause by which the bodies moved (EN I, 362; Drabkin translation, p. 120; see also Frederette’s ‘Galileo’s De Motu Antiquiora’ Physis 14 (1972), 346f). Galileo is here arguing that bodies move upward not because of an internal cause but because of an external cause, viz. the extruding action of the medium. But it seems that even here Galileo cannot be read as attempting to establish the explanatory necessity of external efficient causes. He clearly makes use of an internal cause for his explanation of natural downward motion. External causes then seem to be reserved for explaining effects that cannot be accounted for by the natures of the things in question or effects that are ‘contrary to nature’ (Galileo’s phrase in the passage cited above). Thus, it may be that the only occasions on which external causes are to be invoked are when accidents (as opposed to natures) are involved.Google Scholar
  12. 15.
    In order to reduce notes, in this section I shall put the references to Galileo’s Discorsi e Dimonstrazioni Mathematiche intomo a due nuove scienze into the text, in parentheses following the quotation or attribution. The first page number will be that of the National Edition (EN) (ed. by A. Favaro), Vol VIII (Barbera, Firenze, 1933); the second page number is that of Stillman Drake’s translation, Galileo, Two New Sciences (University of Wisconsin Press, Madison, 1974).Google Scholar
  13. 16.
    Galileo previously discussed such problems with matter and its imperfections in his Dialogo sopra i Due Massimi Sistemi del Mondo (1632), EN 7, 110f and in Day II, 229f. (Santillana’s edition of the Salisbury translation, pp. 95f and 216ff.; University of Chicago Press, Chicago, 1953). In both places Galileo seems to be arguing that mathematical descriptions can be applied to material objects just because the material objects have the property of shape. Considerations concerning the corruptibility or imperfections of matter are irrelevant since they will hold for all matter. Given such constancy the natural philosopher is free to use the supposition that the object in question is like a sphere and then to argue that we can neglect certain sorts of accidents or additions of shape for the purposes at hand.Google Scholar
  14. 17.
    This use of final causes is seen also in the essential argument in Dialogo where Salviati argues from: “Nature does not move to where it is impossible to arrive” (La natura non muove dove e impossible ad arrivare) to the claim that circular motion is the only natural motion (EN, VII, 56; Santillana edition; op. cit., 37).Google Scholar
  15. 18.
    See, for example, Duns Scotus, De Primo Principio, Book II.Google Scholar
  16. 19.
    See note 14.Google Scholar
  17. 22.
    EN, 128–9; Santillana edition, op. cit., 115.Google Scholar

Copyright information

© D. Reidel Publishing Company, Dordrecht, Holland 1978

Authors and Affiliations

  • Peter Machamer
    • 1
  1. 1.University of PittsburghUSA

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