10. DUHEM THE HISTORIAN

 

A special historian

Duhem the physicist, dedicated to the cause of common sense, became a philosopher only in that special sense in which this was required by the ideal of physics he was pursuing. A telltale sign of the special nature of his philosophical quest was his independence of other philosophical schools. He certainly showed no concern for the school of commonsense philosophers. In his turning into not only a historian, but into a special one, he had hardly to be concerned about others. For better or for worse there has never been a school of commonsense historians and certainly not among historians of science, who a hundred years ago were too few to form any school. Anyone aiming at that time at becoming a really good historian of science obeyed common sense by cultivating utmost respect for facts. A brief recall of the notorious fact, much too in evidence in our times, that the utmost respect of a physicist for the facts of the laboratory is hardly ever matched with a similar respect on his part for the facts of the history of physics, should be enough to make that common sense appear in a rather special light. Moreover, a hundred years ago the pivotal facts of scientific history were, as will be seen, known to a much lesser degree than might have been suspected by a scholar bent on as complete a command of facts as possible. There was, of course, nothing special in looking at that time on facts as forming an organic succession. The Comtean view of history, which young Duhem imbued from Cons, his history teacher at Stanislas, and which constituted a climate of opinion, rested on such an outlook. It could seem a dictate of plain common sense.

Both with respect to utmost reverence for the historical record and to the organic continuity of the historical process Duhem could find impressive encouragement in the Ecole Normale which had in the 1870s and 1880s the historian Numa Denis Fustel de Coulanges as its chief luminary. Duhem was very much aware of Fustel’s bent on utmost respect for the record. Thirty or so years after he had left the Ecole he pointedly recalled Fustel’s insistent question, ‘Do you have a text?’ and he did so in a context replete with his references to common sense as the

 

 

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ultimate criterion of any proposition, however learned.t As to the continuity, what he could absorb through intellectual osmosis at the Ecole should seem even more telling. He could hardly be unfamiliar with the often-quoted passage in Eustel’s famed analysis of Greco-Roman social history:

 

Fortunately, the past never completely dies for man. He may forget it, but he always preserves it within him. For, take him at any epoch, and he is the product, the epitome, of all the earlier epochs. Let him look into his own soul, and he can find and distinguish these different epochs by what each of them has left within him.2

 

Even more important should seem for the formation of Duhem the historian the chief message of Fustel’s classic. Its author argued that the three great social revolutions of classical times the dethroning of theocratic kings, the breaking up of the gens as a family, and the entering of the plebs into the political life —were but vehicles of a continuity: the gradual extension of the idea of mutual responsibility which found its fulfillment in the advent of Christianity. Much the same was argued with respect to modern history by Gabriel Monod, also a professor of history at the Ecole. In launching in 1876 the Revue historique, an organ more secular than the older Revue des questions historiques, Monod exhorted its future contributors to see the logical connection which secures continuity even across such chasms as the French Revolution, the Protestant Reformation, and the Renaissance. As to contemporary interest in history, Monod merely had to register it:

‘Our century is the century of history.’3

The thrust of the phrase was evolution through time. Duhem’s fondness for the evolutionary perspective was certainly evidenced in his high esteem for the famed study of modern French history by H. Tame,4 a protagonist of Darwinism in political as well as intellectual history. Not that the common sense of Duhem would have subscribed to evolution in terms of blind chance. He emphatically rejected the portrayal of human history as seen through the inexorable struggle of the survival of the fittest which leaves no room for purpose. As a professor, who had to preside over examinations for licence, which included even for students of physics the topic of evolution, he was wont to deliver a scathing expos6

 

 

l.La science allemande, 1915 (2), p. 90. Fustel attached even greater importance to the impartiality with which the historian was to read the documents. See his inaugural lecture of his course on medieval history at the Sorbonne, the text of which was immediately printed in Revue politique etlittdraire 8 (Feb. 8, t879):745-51 ;especially p.746.

2. Quoted from the English translation, The Ancient City: A Study on the Religion, Laws, and Institutions of Ancient Greece and Rome, by W. Small (4th ed.; Boston: Lee & Shepard, 1882, p. 13) of Fustel’s classic, La citd antique, first published in 1864; it had already gone through a dozen editions by the time Duhem completed his studies at the Ecole.

3. G. Monod, ‘Du progr~s des etudes historiques en France depuis le XVIe si~cle,’ Revue historique 1 (1876):5-38;see p. 27.

4. Sec Un savant fran cais, pp. 129-30.

 

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of the logical fallacies of Darwinism and dismiss the candidate with a good mark.5 He put himself on record in that connection in a context in which he evaluated the first volume of a vast Church history by his good friend, Albert Dufourcq. The two main points which Duhem warmly endorsed about the procedure of Dufourcq were obviously also valid for Duhem the historian. The time, January 1904, was also most significant. As will be seen, it was about that time that Duhem caught a glimpse of the remote — medieval — origins of classical physics and, through the relentless pursuit of the documentary evidence, he became a historian. One of the two points was the meaninglessness of an evolutionary rationalism contemptuous of a development evincing purpose which transcends mere material existence:

 

The work of chance or rather the inextricable weaving of fatal consequences produced by the interplay of laws with no purpose, this is what rationalism sees in the history of mankind; it merely sees the evolution of an animal species; the evolution of a species

· . . where some individuals, in order to achieve a greater mastery over the forces of nature, invented the sciences whose sole legitimate objective is to increase the dose of physical enjoyments allotted to each representative of the species; an evolution with no purpose for the individual whom chemical forces will dissolve after the few years in which he experienced more bitterness than joy; an evolution with no purpose for the species whose last representatives will die of cold and hunger on a frozen planet where no geologist ever will exhume their fossils.

 

In such a ‘rationalist’ view it was impossible to argue, and this was Duhem’s first main point, that human history stood in the service of the unfolding of any idea, let alone of the great idea that ‘the goal of history is the realization of a common consciousness for mankind and that Christianity is the form of that universal consciousness.’

The other point related to the manner in which the historical unfolding of a great idea should be told by the historian. Those familiar with the writings of Duhem the historian will not fail to perceive the applicability to the history of science of his comments on Dufourcq’s procedure:

 

This great idea does not unfold itself under our eyes in the manner of philosophical

dissertations. In line with the method dear to our modern historical school, that great idea does not want to be expressed in general propositions. It rather reveals itself as it has developed in the world, concretely and alive; it will speak through the mouths of those who had for their mission to teach humankind; it will vibrate in the tremblings of populist pressures, of upheavals, and of revolutions; one will see it run beneath the

 

5. See note 43 to Ch. 5. The good mark was, at least on one occasion, not the only price paid by Duhem, as recalled by Flotte, professeur honorahe at the University of Bordeaux, who had Duhem as one of his examiners around 1910. From criticizing Darwinism Duhem passed to criticizing its teachers and then turned to the young candidate: ‘If only I could get hold of your teacher!’ The teacher happened to be in the audience, stood up, confronted Duhem. The incident was officially reported to the rector, Thamin, who saved Duhem from embarrassment by securing a quick promotion for the teacher. The first-hand information on the story is P. Brouzeng, in his doctoral dissertation, ‘L’oeuvre scientifique de Pierre Duhem . . . (see note 222toCh. 8), 1:33.

 

 

 

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crowded medley of events. Be it the speech of man or the recital of facts, all has passed

through the crucible of severe critique · · · ‘6

 

In Duhem’s case the crucible was the superhuman effort he expended over a dozen years to track down and set forth that record in its overwhelming and wholly unsuspected richness, In that sense too he was a very special historian. However, he would not have become a historian of physics in any special sense had his interest in physics not been very special. The special perspective of Duhem the historian was set by his theory of physical science according to which physics, having commonsense data and truths as its basis, was to remain, for its own good, free of hypotheses about the internal nature of matter. Duhem believed, and this is what made him a historian, that the historical survey of any major topic of physics would support the correctness of that perspective anchored in common sense. Tellingly, his Thaite~ d’Energ~tique, the great synthesis of his work in physics, began with a reference to his historical researches. In speaking of the final justification of the criteria which in his view had to guide the choice of physicist among various methods, he declared:

 

The guidance is provided for us by our knowledge of the past of science. Principles have been formulated which were found to be in contradiction with experience. Other principles were put in their places which enjoyed a partial confirmation. These in turn were modified, corrected, securing with each step more exact agreement of their corollaries with facts. We are reassured that the garment of which we here cut out the shape will exactly fit the body wbich it has to cover because the customer had to have repeated fittings.7

 

The essays which Duhem published between 1893 and 1897 on the history of atomic dotation, of gravitational theories, of mechanical models, and on the evolution of science since the 17th century, have therefore an interest of their own. Written as they were in the same years when Duhem advanced a philosophically articulated view of what he was supposed to do as a physicist, who satisfied the dictates of logic and common sense, those essays also mark the making of Duhem the historian of physics in that specific sense. Apart from showing the specifically interpretative interest of their author in the history of his subject matter, physics, those essays also show his bent on rigor, another aspect of his interest in physics. Rigor in matters historical means above all a reliance on original sources. Such a reliance is an immediate antidote against being trapped in the perennial disease of repeating clich6s, let alone of making up history. Those essays earned for Duhem the reputation of being an expert on the history of physics so effectively that soundings were made from high levels about his availability for the chair of the history of science at the Collage de France.8 In reading those essays one meets

 

6. Translated from Duhem’s review of the first volume of Dufourcq’s L ‘avenir du christianisme. Introduction. La vie et la pensde chrdtienne dans le passe’ (Paris: Blood et Cie, 1904,

x + 799pp) in RQSc 55 (1904):252-54.

7.1911(1), 1:5.

8. See Jordan, ‘Duhem,’ p. 162, and Ch. 4.

 

 

379

 

with that type of physicist who unhesitatingly goes to the sources, even though written in Latin, and who knows what is the best among those sources. While quoting decisive passages from the works of a Descartes, a Huygens, and a Leibniz was already more than physicists dabbling in history would have done, only a born historian, determined to get the best evidence, would have taken the trouble of perusing an elusive book by such an elusive author as De Gamaches, a rear-guard Cartesian from the mid-eighteenth century.9 The last of those early essays, the one on the evolution of physics from the 17th century, comes to a close with two statements, each giving an early and important glimpse of Duhem the historian. In the first Duhem asserts the Aristotelian character of what is lasting in physics as evidenced in its latest development, thermodynamics. The second statement is no less noteworthy, partly because it gave rise to snide remarks rather than to serious criticism ready to face up to the ultimate implications of its own logic. In registering the return, though a very qualified one, of modern physics to some Aristotelian positions, Duhem may have easily confined himself to a remark celebrating the force with which logic asserts itself in the long run. Duhem was never a mere logician. The process is, in his eyes, rather an evidence that in the tortuous development of physical theory there is at work a superior directive force, Divine Providence:

 

Impatient to leave the terrain where the physics of the Scholastics enclosed it, the human spirit took three centuries and thousands of scientists to chart a road for itself toward the true science of the material universe. The direction of this road has very often changed, and today we register with astonishment that it returns upon itself by leading us to the point of departure. And yet, in that immense effort, there is no laborer whose work is lost. Not that the work has always served the goal intended by its author; the role which that work plays in the science of today often differs from tlie role which he assigned to it; it rather took the place designated in advance by the One who governs all that activity.10

 

Debunkers of such an elevated and far reaching perspective were, until rather recently, unwilling to see even that far where the idea of progress, once severed from metaphysics, becomes a disbelief in progress.11 Duhem’s belief in progress, expressed in the foregoing ~assage, never wavered, The same passage also gives a glimpse of related ideas rfear to Duhem: the slowness of progress, the contribution to it by thousands of workers, and its frequent departures from the

 

9. The context was Duhem’s essay-review of Leray’s mechanical explanation of gravitational attraction (‘Une nouvelle th~orie ‘ 1893 [71, see especially pp. 114-23). Etienne-Simon de Gamaches (1672-1756), canon of Sainte-Croix de Ia Bretonnerie and member of the Acad~mie des Sciences, had previously published Systi~me do mouvement (1721), another effort of his to reconcile Cartesianism with Newtonianism.

10. ‘L’~volution des theories physiques . . . ,‘ 1896 (11), p.499.

11. Or as J. B. Bury, author of The Idea of Progress:An Inquiry into its Origin and Growth (1932: New York: Dover, 1960), mused with an eye on some tacit assumptions of Darwinian and Spencerian evolutionism: ‘But if we accept the reasonings on which the dogma of Progress is based, must we not carry them to their full conclusion? In escaping from the illusion of finality, is it legitimate to exempt that dogma itself?’ (pp. 35 1-53).

 

 

 

380

 

right direction. The kind of histories of physics which Duhem was to write on such a basis was well exemplified in the first half of his Evolution de la m&anique. There in fourteen chapters he gave a carefully documented account of a progress stretching from Aristotle to Hertz’s mechanics and Kelvin’s vortex atom. Well over three-fourths of that first half were devoted to the last hundred years, starting with the place of the idea of virtual velocities in Lagrange’s statics. Duhem was a physicist’s historian not an antiquarian. For him remote stages in the history of exact science could not rival phases of its recent development. The importance which he assigned to the role of virtual velocities was a dictate of interpretation, a dictate imposed from the standpoint of theoretical physics. Not history but theoretical insight made Duhem perceive the striking similarity between the thermodynamic potential and the principle of virtual velocities, That the latter was the germ out of which Lagrangian mechanics arose was also a point which took more a theoretician than a historian to perceive.

In respect to clarity of insight, richness of historical data, and grasp of the essential those fourteen chapters surpassed anything available at that time as an overview of the history of mechanics, restricted as was the perspective.12 Those familiar with Duhem’s essay from 1896 on the evolution of physics from the 17th century on were not surprised by his portrayal of the principal features of that development, which Duhem described above all as a genuine growth, an evolution. Being such a growth, it was to be open-ended. Then, as well as years later, Duhem was far from thinking that his thermodynamics or energetics was the last word in physics. He spoke of himself as he cautioned: ‘It would be quite presumptuous to imagine that the system for whose achievement the physicist works will escape the fate common to the systems that have preceded it and will merit lasting longer than they.’ 13 But precisely because that evolution was a genuine growth, the theoretician, mindful of the necessary imperfection of his product, did not have to despair: ‘each of the stages of this evolution is the natural corollary of the stages that have preceded it; it is the chief part of the stages which will follow it. Meditation upon this law has to be the theoretician’s solace.’14

Thus, although the faint echoing by the latest in mechanics, or energetics, of

some peripatetic notions could appear as a counterrevolution, especially to latter-

day Cartesians, it did not have to be viewed as something disruptive. While often

 

12. That historical part of Duhem’s Evolution de la mdcanique presented, with its emphasis on 19th-century developments, a startling contrast even to Mach’s Die Mechanik in ihrer Entwicklung (1883), a work in its 4th edition by 1901. Duhem may have first learned about the main points and general trend of Mach’s book through a review of it in BScM 10 (1886):

97-99, In that review, written by H. (Hermite?), pointed reference was made to virtual velocity as the basis of all questions concerning equilibria according to Lagrange’s Me’ canique analytique (see note 26 below), a work on which Mach heavily relied. Duhem confined his criticism of Mach’s work to a few factual details in the long review he wrote in 1903 of its French translation, 1903 (30). The half dozen letters, all brief and curteous, exchanged between Mach and Duhem, contain only generalities.

13. The Evolution of Mechanics, 1980 (l),p. 189.

14. Ibid., p. 188.

 

 

 

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making a recourse to the terms revolution and counterrevolution, Duhem seemed to be always aware of that marvellous insight provided by common sense into the true nature of both, an insight epitomized in the old saying: plus qa change, plus c’est la meme chose. The next-to-last paragraph of the book was an amplification on the conclusion of the essay from 1896, with one difference though. Possibly because now he was writing to a wide scientific public Duhem did not ascribe the organic growth of science to a Providence governing it but to an Jd~e directrice.15 For those able to see in that icke more than teasing rhetoric, Providence was waiting in the wing. Duhem had no intention to quarrel with those for whom such an icke, through the inept reification of a concept, was a convenient evasion of deeper questions.

Duhem was clearly fascinated by the topic, the history of which he had to keep within strict limits for the readers of the Revue g~n~rale des sciences. His fascination demanded an outlet with generous concessions of space which he found in the Revue des questions scientifiques owing to the interest of its director, a Jesuit priest, P&e Julien Thirion, a historian of mathematics and professor of physics at Louvain.16 Tellingly, Duhem did not find worth pursuing a theme which, as he put it in the first installment of his series of articles on the evolution of mechanics:

‘would be an interesting task.’ It would have consisted in portraying a ‘sudden turn of fortune’ for the sciences, once a break was made with the Aristotelian physics of qualities during ‘the renaissance of the science at the beginning of the seventeenth century.’17 Not that Duhem would have subscribed to Moliere’s lampooning of scholastic thought as a mere evasion of issues by phrases such as ‘virtus dormitiva’ as the alleged cause of sleep induced by certain substances. Had the task appeared to have the kind of philosophical instructiveness which bears on physics, Duhem certainly would have already paid attention to it. But was there any real science to look for in the Middle Ages? A mere look at the best histories of science available in 1903 was enough to cure him of any illusion. They contained at most a generic reference to a few, such as Grosseteste, Roger Bacon, and Sacrobosco, who by some curious aberration from prevailing preferences took an interest in the little Greek science that had come down to them. For Whewell the Middle Ages remained a ‘mid-day slumber.’18 In the first edition (1837) of his History of the Inductive Sciences the post-Greek story really began with Stevin, and in the second edition (1847), published after Whewell’s exposure to Leonardo’s manuscripts in Paris, with Leonardo himself.19 Mach’s history of mechanics had but sarcastic

 

 

15. Ibid. Duhem had in mind Claude Bernard,as is clear from a similar reference by Duhem to the idde directrice in the conclusion of his Origines de Ia statique; see 1906 (3), p. 289.

16. For an account of his life and work, see V. Schaeffers, ‘Le R. P. Julien Thirion,’ RQSc

77 (1920):27-50.

17. The Evolution of Mechanics, p.5.

18. W. Whewell, History of the Inductive Sciences (3rd ed., 1857; reprinted, London:

Frank Cass, 1967), 1:9.

19. Tellingly, Whewell discovered even a Roger Bacon only in the third edition (1857) of his History

 

382

 

words for an age steeped in theology.20 The histories of physics published in 1880s by J. C. Poggendorff,21 F. Rosenberger,22 and A. Heller23 were hardly an improvement on the little which Duhem could find in the much earlier work of J. E. Montucla24 with respect to the 14th and 15th centuries. Different was the case as he pursued G. Libri’s work, already in print for over sixty years, when he first quoted it in 1903. There he found a reference to Leonardo’s notion of virtual velocity, a matter, as he immediately noted, of ‘utmost importance.’25 This meant the extension of the history of mechanics a hundred years farther back than Galileo, who was the start of that science in the historical introduction which Lagrange prefixed to his Mecanique analytique,26 a work familiar to Duhem for some time. Beyond Leonardo there was in all appearance nothing to look for. The heavy lines which separated the section on the Greeks and the one on Leonardo

 

20. A subtle evidence of Mach’s contempt for the inedievals was his refusal to refer to them as such after he had to acknowledge Duhem’s findings on the medieval origins of statics and

on the medieval forerunners of Leonardo.

21. Poggendorff’s Geschichte der Physik, the text of his lectures at the University of Berlin (Leipzig: J. A. Barth, 1879), was available in French since 1883.

22. The three volumes of Rosenberger’s Die Geschichte der Physik (Braunschweig: F. Vieweg) were published between 1882 and 1890.

23. Heller’s Geschichte der Physik von Aristoteles his auf die neueste Zeit (1882) was reprinted in 1965 (Wiesbaden: M. S~ndig). Compared with these works, only superficial popularization of the subject could be found in the two-volume Histoire de Ia physique et de la chimie depuis les temps les plus reculds iusqu’iz nor jours (Paris: Firmin Didot Fr’eres, 1866-69) by Jean-Chr6tien-Ferdinand Hofer, a German-born French polygraph. His histoires of astronomy, botany, and mathematics were on the same level. The twelve volumes, comprising almost 3000 pages, of the Histoire des sciences marhdmariques et physiqoes, which Maximiien Marie, r6p~titeur at the Ecole Polyrechnique, published between 1883 and 1887 (Paris:

Gauthier-Villars), had their sumptuous printing as their only commendable feature. Scientific history for Marie existed in listing scientists in chronological order.

24. Jean-Etienne Montucla’s Histoire des mathe’matiques, first published in two volumes in

1758, saw a second edition in four volumes in 1799 (the increase relating mostly to 18th-

century developments), and a reprinting in 1968 (Paris: Blanchard).

25. See 1903 (16), p.475 and 1905 (11), p. 13. The reference was to Libri’s four-volume Histoire des sciences mathe’matiques en Italie depuis Ia Renaissance des lettresjusqu’4 Ia fin du xviie si~cle (Paris: J. Renouard, 1838-41). Duhem then quickly found out that Libri’s statement (3:27) was a summary of the less than one page on the topic in the Essai sur Icr ouvrages physico-mathe’matiques de Le’onard de Vinci, avec des fragments tirds de ses manoscrits, apportds de l’Italie (Paris: chez Duprat, An V 117971) of J. B. Venturi, professor of physics in the lyceum of Modena, who read sections of it before the Acad6mie des Sciences (Institut National des Sciences et Arts) as part of a general reporting on the artistic, scientific, and literary riches seized by French troops in Italy. The entire second half of the 56-page essay was on Leonardo’s life and painting (pp. 33-57). Concerning Leonardo’s physical science Venturi spoke ‘of a few nuggets in a heap of useless sand’ (p.5). Among these were Leonardo’s dicta on statics and on descent on an inclined plane, which Venturi summed up in two short chapters (pp. 17-2 1) with some references to the entries in the manuscripts. There was no hint whatever in Venturi’s essay about the possible indebtedness of Leonardo to some earlier writers.

26. J. L. Lagrange, Me’ canique analytique (new enlarged edition; Paris: Mine Ve Courcier,

1811), 1:221. Concerning the science of statics, Lagrange moved directly from Archimedes to

Stevin (ibid., p. 2).

 

 

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in E. Wohiwill’s long essay on the origin of the law of inertia, published in 1883-84,27 was symbolic of a dark cleavage that apparently separated classical times from the rebirth of learning during the Renaissance.

Such an appearance had by then been a long-standing dogma of intellectual respectability. When in his preliminary discourse to the Encyclop~die d’Alembert spoke of the Dark Ages, he merely repeated a cliche dear to humanists as well as to reformers.28 Irony was not of course lacking. Contempt for the Middle Ages was in part responsible for the speculations of Bailly, author of the first modern history of astronomy, about the birth of science in a mythical antediluvean culture somewhere in Outer Mongolia, speculations which earned him well-deserved ridicule.29 To be sure, the Middle Ages regained sentimental respectability after the French Revolution showed something of the terrifying darkness which ‘enlightened’ reason could produce. It was gradually perceived that the small concession which Condorcet granted to the medievals30 had to be enlarged if the law of three phases (adumbrated by Turgot, enunciated by Saint-Simon, and exploited by Corute) was to retain historical reliability.31 Yet, what was granted in one breath was taken back in the next. A typical example of this was provided by Victor Cousin who, in speaking at the start of his survey of modern philosophy about the Middle Ages as one of the great and splendid phases of history, hastened to add that all its achievements necessarily turned into so many hindrances of progress.32 Such a seemingly sophisticated discrediting of the Middle Ages could much more effectively sway the unwary than patently violent remarks of which leading pundits of the Third Republic often delivered themselves. Thus H. Tame described the

 

 

27. ~Die Entdeckung des Beharrungsgestzes,’ Zeitschrift fl2r Volkerpsychologie und Sprachwissenschaft 14 (1883):365410 and 15 (1884):337-87. For that horizontal line, see the first article, p. 380. WohIwill, whose chief sources were Whewell, Poggendorff, and Mach, had, needless to say, no inkling of Buridan. He briefly mentioned Roger Bacon, but only in an appendix to the second article (p. 384). Wohiwill is better remembered for a two-volume work (1909-26) on Galileo and his struggle on behalf of Copernicanism.

28. For a documentation of early Protestant dicta on the Middle Ages, see W. K. Ferguson, The Renaissance in Historical Thought: Four Centuries of Interpretation (Cambridve, MA:

Houghton Mifflin Co., 1948), pp. 46-58.

29. For details and documentation, see my Fremantle Lectures (Oxford), The Origin of Science and the Science of its Origin (Edinburgh: Scottish Academic Press, 1978), pp. 3942.

30. In his Esquisse d’un tableau des progris de I’esprit humain Condorcet credited the Schoolmen with more precise notions about the Supreme Being, with the distinction between the First Cause and the universe,and between mind and matter, with the different meanings of the word liberty, with the meaning of creation, with analysis of the various operations of the human mind, and with the classification of ideas (see modern English translation by J. Barraclough with an introduction by S. Hampshire, Sketch for a Historical Picture of the Progress of the Human Mind [New York: Noonday Press 19551, p. 95). Condorcet failed to perceive how momentous were those small concessions.

31. See Bury, The Idea of Progress, pp. 262-65.

32. V. Cousin, Cours de l’histoire de la philosophie, the text of Cousin’s lectures during

18 19-20 at the Sorbonne, was again published as Cours de philosophie. . . Histoire de Ia

philosophie (Bruxelles: Soci~t6 Belge de Libraire, 1840); see 1:9-10.

 

384

 

 

assault of schoolmen on the fortress of truth as a breakthrough which made them fall ‘to the bottom of a dark ditch where three centuries of work could not enrich the human mind with a single notion.’33 While Duhem could easily see through such claims as far as philosophy, the arts, and social development were concerned, he could hardly guess that the claim was utterly hollow with respect to the sciences.

Nothing was therefore more natural for Duhem than to move directly from Archimedean statics to Leonardo and state: ‘The commentaries of the scholastics on the ‘mechanical problems’ of Aristotle do not add anything essential to the ideas of the Stagerite. In order to see these ideas issue in new offshoots and bear new fruit we must wait for the beginning of the 16th century,’ that is, Leonardo da Vinci. So began the second chapter in that 60-page-long first instalment on the origins of statics which Duhem wrote in the late spring and early summer of 1903 and which saw print in the October issue of the Revue des questions scientifiques. 34 Concerning the scholastics he did not refer to any commentary. Possibly he saw one or two in the printed works of the great scholastics, and satisfied himself that no scholastic, great or minor, offered on the question pages worth studying. As far as the sciences were concerned he saw no reason to challenge the shibboleth about the darkness of the Middle Ages. Certainly no such challenge was intimated in Libri’s history of the mathematical sciences in Italy35 which Duhem took for a first guide. Again, there was no hint to scholastic predecessors of Leonardo in the introduction which Charles L. Ravaisson-Mollien wrote to his edition of Leonardo’s manuscripts in the Biblioth~que Nationale,36 an edition on which Duhem heavily relied.

 

To unsuspected headwaters

Duhem did not have to discover Cardan as a main link between Leonardo and Galileo, nor did he have to study manuscripts in order to form himself a fair idea of Cardan’s contributions. Long as that first instalment was and expressive of the two thousand years stretching from Aristotle to Cardan, it could be written

 

33. H. Tame, Histoire de la litte’rature anglaise (2d rev, enlarged ed.; Paris: Hachette, 1866-

78), 1:223. How far and wide Tame’s dictum was carried can easily be gathered from the fact that this five-volume work went through ten printings before the end of the 19th century. Effectively as such statements could be rebutted at that time by Catholic scholars with respect to philosophy and the arts, they hardly sounded convincing as they took up the sciences, mathematical and empirical. Good illustrations, of this ineffectiveness are the chapters ‘Les sciences math~matiques’ (pp. 3 13-28) and ‘Les sciences physiques et naturelles’ (pp. 32944) in Le treizi~me si~cle litte’raire et scientifique (Bruges: Soci6t~ de Saint Augustin, 1894) by Albert Lecoy de la Marche, one of the better works of that type.

34.Lesoriginesdelastatique, 1905(11), 1:13.

35. According to Libri, even mathematics, the only scientific field worth mentioning about the Middle Ages, was in ‘a deplorable state’ with the exception of some efforts made in Italy

(2:156-64).

36. Ravaisson-Mollien was concerned mainly with the origin and history of the material he edited in the long preface to the first of the six folio volumes of Les manuscrits de Le’onard de

Vinci (Paris: A. Quantin, 1881-91).

 

 

385

 

with relative ease. Duhem expected only diligent study of already published material, especially the writings of Benedetti and Stevin, to carry on his project to the point where such intensely researched figures as Descartes and Galileo would take their turn in his narration. Contrary to the expectations of the readers and the editor of the Revue des questions scient(fiques, familiar with Duhem’s efficiency, the next instalment failed to come as scheduled.

The reason for this was correctly guessed by H. Bosmans, a Jesuit professor of mathematics at the College St. Michel in Bruxelles and an expert on the mathematics of the 16th century.37 Sometime after the publication in October 1903 of the first installment, Fr. Bosmans visited Fr. Thirion in Louvain. Their conversation quickly turned to Duhem’s project and Bosmans wondered whether he could take a look at the rest of the manuscript. ‘I do not have it,’ Fr. Thirion replied. ‘Duhem has not finished it yet. He still has lots of reading to do. He promised me further chapters at the rate at which he writes thens.’ ‘In that case,’ Bosmans replied,

 

I would not be surprised if his new readings would not convince Duhem to add complementary chapters to the period whose history he has just written. I myself read Stevin a great deal. The man from Bruges further developed Archimedes and Cardan, but seems to ignore wholly Leonardo to whom Duhem attributes so great importance. If Stevin underwent Leonardo’s influence, he did so in any case only very indirectly. On the other hand I know two small treatises ‘de ponderibus’, both attributed to Jordanus de Nemore. Duhem will end by finding them and I would be surprised if he were not to attribute some importance to them.38

 

Duhem, as Bosmans added in recounting his words to Thirion, had by then made that find, owing to his bent on rigor and accuracy. He perused works of Tartaglia although his name, as he put it, ‘is hardly pronounced in any history of statics.’ This remark of Duhem is part of his famous preface to the first volume of the Origines de la statique,39 where he disclosed the reason for the delay by three months of the second installment of his story. Readers of the first installment could confidently expect further interesting novelties from Duhem, who had just exposed the plagiarism of Cardan as a transmitter of important ideas of Leonardo to Descartes and Galileo. But neither those readers nor Duhem expected a novel find which would turn upside down well established views on the genesis of modern science.

Yet this is what was to come, In the second installment which appeared in

April 1904, Duhem merely suggested a revolutionary finding. He presented there

the reflections of medieval Arabs and Christians on a treatise on weights attributed

 

37. The P~re Bosmans was the author of 241 articles and 278 reviews which are listed in Archives internationales d’histoire des sciences 3 (t950):6t9-56. A year earlier Sarton made an appeal in Isis for the republication of at least the major articles written by Bosmans, whose life and work was treated by A. Rome in Isis 12 (1929):88-tt2.

38. H. Bosmans, ‘Pierre Duhem (1861-1916): Notice sur ses travaux relatifs ~ l’histoire des sciences,’RQSc 80 (1921):40-1 and 42747.

39. Les origines de Ia statique, 1 ii.

 

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to Euclid, and added that those reflections refuted the view of Montucla (whose more than a hundred-year-old history of mathematical sciences in four volumes was still authoritative) according to whom the contents of that treatise were but the ‘stutterings of a nascent physics.’40 On the contrary, Duhem remarked, the treatise was seminal in producing in medieval times reflections very crucial for the future of physics. Although Jordanus de Nemore was repeatedly mentioned in the April installment, readers of the Revue could hardly have expected to be told by Duhem in the July installment that they would now be treated to some ‘ingenious efforts whose fruitfulness has not yet been exhausted . . . We shall now see the Western mind get hold of debris [transmitted by the Arabsj . . . We shall assist at a work of transformation and organization, prodigiously intense and powerful, which will produce modern statics.’4t After discussing Jordanus de Nemore over twenty pages Duhem declared:

 

The equilibrium of the balance as a function of the equality between motor virtual work and resistance virtual work is the first seed of a principle whose full development will be reached only at the end of the 18th century in the Me’ canique analytique of Lagrange. The study of the evolution by which this seed, minute in appearance, has arrived at its full form, under which we view it today, will be one of the principal objects of this study.42

 

In the October issue, which carried the story beyond Jordanus de Nemore to Leonardo da Vinci, Duhem began with the declaration: ‘Science does not know of spontaneous generation. Not even the most unforeseen discoveries have ever been made in all detail in the mind which generated them.’43 Ominous words, especially if part of a story inching closer to that Galileo whose inclined plane had by then become the secular equivalent of Jacob’s ladder. Its mystique made itself felt in most varied contexts, such as, to speak only of those years, in Bergson’s Evolution cr~atrice, where it was spoken of as the very vehicle on which science descended upon the earth.44 In the January 1905 issue Duhem threw down the gauntlet:

‘In the very entourage of Galileo, there was familiarity with that old writing [of Jordanus] whose statics on certain points surpasses all that was given on that subject by the Florentine geometer.’45 Everything was now ready for calling a spade a spade, which Duhem did in the April issue. In pointing his finger at Descartes’s ‘prodigious arrogance, which saw only errors in the past,’ Duhem also evoked the guilt of modern times born in the spirit of Descartes who ‘in his bril

 

 

40. Ibid ., p. 79.

41. Ibid., p. 98.

42. Ibid., p. 123.

43. Ibid., p. 156.

44. See Creative Evolution, authorized translation by A. Mitchell (New York: Modern Library, 1944), p. 364. The remark was all the more startling because Bergson was aware of Duhem as attested by his reference in the same work (p. 264) to Duhem’s Evolution de la me’canique, which Bergson quoted with approval on the question of qualities.

45. Les origines de Ia statique, 1:262.

 

 

 

387

 

liant essay on statics said nothing that would not have been known long before

him, in the school launched by Jordanus.’46

Meanwhile Duhem penned his preface to the first volume of his Origines de la statique, made up of the six installments, to be published immediately in book form by A. Hermann in Paris, The date, March 21, 1905, of that preface is a momentous event in the historiography of science. Although myths have a long survival value, a beacon of light was on that day turned on for those who wanted to see it, In that light the established tenet about a sudden enlightenment in the early 17th century became a spurious glitter:

 

The science of mechanics and physics, of which modern times are so rightfully proud, derives in an uninterrupted sequence of hardly visible improvements from doctrines professed in medieval schools. The pretended intellectual revolutions were all too often but slow and long-prepared evolutions. The so-called renaissances were often but unjust and sterile reactions. Respect for tradition is an essential condition of scientific progress.47

 

As Duhem penned that preface, he was already writing the second volume, consisting of five installments, published between July 1905 and July 1906. They began with the medieval contributions to the problem of the center of gravity. In Duhem’s portrayal of Albert of Saxony another medieval scientist, and no less important than Jordanus de Nemore, emerged on the scene. The installment, almost a hundred pages long, contained a footnote which referred to an article by Duhem on Albert of Saxony and Leonardo, just published in the Bulletin Italien.48 Further installments contained references to further articles by Duhem on related topics in the same Bulletin. Duhem seemed to be overwhelmed by new vistas and he was not to be delayed in his bold advance toward the headwaters of science on an unsuspected continent. That in the process he had eyes for uncounted details is in itself an object of wonder. That he refused to be bogged down in minutiae, so that he might say the last word on any and all details, should be admired even more. Had Columbus been willing to embark on his historic voyage only after having on hand an exact chart of all currents of the Atlantic, America would not have been discovered until much later. Nor would Bohr’s name be known today had he wanted right at the outset a theory of the hydrogen atom that could cope with all the complexities of its spectrum. Without viewing Duhem’s bold march in this light, references to his findings will be so many occasions for mediocre talents to appear bigger by finding fault with the often startling opinions and conclusions of a genius.

Such a conclusion was offered in the second installment with respect to the socalled Copernican revolution and the true intellectual merits of the 16th century, the century of the Renaissance. On the former, Duhem pointed out the many traditional facets which Copernicus carefully retained. On the latter, Duhem

 

46. Ibid., p. 352.

47. Ibid., p. 2 :iv.

48. Ibid., p.91. The article in question was 1905 (18).

 

388

 

singled out rigid Averroism, so averse to science, as a distinctive feature of the 16th century. Long hallowed clich6s were unmasked as Duhem concluded the second installment which brought the history of statics up to Torricelli’s principle:

 

By the very moment when the writing, which assured for Galileo the priority of that principle (provided one does not have to trace it to Leonardo), was printed, the geometers had for ten years been in the habit of attributing it to Torricelli. The history of the principle of Galileo and Torricelli offers us a remarkable example of the continuity along which scientific ideas most often develop. We could follow that development as the naturalist follows the development of an organism.49

 

Looking in such a way at past developments was central to Duhem’s philosophy of science in which the last word belonged to the witness of history. Duhem obviously was elated that a hitherto unexplored terrain, the science of four centuries before Galileo, was providing massive evidence on behalf of his theory of physics. Herein lies a principal explanation of the all-consuming zeal with which, from the late Fall of 1903 on, he delved deeper and deeper into historical research. A case in point is the paragraph which brought to a close his analysis of Torricelli’s principle on the pressure of the air. In its unobjectionable form given to it by Torncelli, Duhem saw a classic illustration of the typical development of physics leading to pure formalism:

 

Torricelli made disappear all traces of the erroneous doctrine to which that principle gave birth. As many other propositions of physics, it is by denying its own origin that Torricelli’s iaw became an irreproachable truth. But by breaking all links with the error which gave birth to it, it lost the apparent evidence which seemed to impose its acceptance. It showed henceforth what it really had been: a pure postulate justified only through the agreement of its consequence with reality.50

 

 

Continuity through Leonardo

The last two installments published in April and July 1906 need not detain us. They dealt, with undeniable freshness though, with a phase of the story, stretching from Mersenne to Varignon in the early 18th century, a phase already explored in its essential features. But the grand conclusion of all five installments is worth recalling. It was introduced with Duhem’s graphic description of Vis, a river in the C~vennes, one of his favorite hiking grounds, which suddenly disappears in underground cavities, breaks to the surface again miles downstream, forms a stretch of a narrow gorge strewn with dry stones, before, at long last, it turns into a steady onrush of water.51 Such was in Duhem’s eyes the perfect image of the view according to which if there was any connection between Greek and Renaissance science, it was merely a long arid stretch: ‘Senseless history,’ Duhem cried out:

 

The historian, who is fond of simple and superficial views, celebrates the lightning discoveries which make the full daylight of truth to succeed the profound night of ignorance and darkness. But the one who subjects to a penetrating and detailed analysis the most novel and apparently most unexpected discovery, finds there almost invariably

49. Ibid., p. 150.

50. Ibid., p. 185.

51. For that passage in English translation see p. 148 above.

 

 

 

389

 

the result of a vast amount of imperceptible efforts and the confluence of an infinity of obscure trends. Each phase of the evolution which slowly leads science to its completion appears to that historian to be marked by two characteristics: continuity and complexity.52

 

This continuity did not foreclose the role of geniuses. Duhem described Leonardo da Vinci as one who turned the flow of science into a ‘tempestuous torrent.’53 But because the flow was already there he was not ‘the seer who suddenly discovers truths unsuspected until then.’ The historical record was hardly more favorable to ‘the legend which made Galileo the creator of modern dynamics.’ The legend, if not the legendary figure, was the product of a ‘too summary and too schematic historiography which made us behold a renaissance of the scientific method, forgotten since the Greeks, where we see the natural development of mechanics during the Middle Ages.’ Descartes was cut to size as Duhem put his finger on the ‘pride of the author of Cartesianism which duped the world into taking Cartesianism for a product curiously unforeseen and unsuspected.’ The truth was an organic development, which Duhem illustrated with a simile in which both continuity and novelty were done full justice in an exemplary balance. The simile was also a warning which, in view of subsequent developments, may very well be the most needed and most ignored warning that could be addressed to latter-day historians of science: ‘The graceful flight of the butterfly with glistening wings makes one forget the slow and painful crawling of the humble and somber caterpillar.’54 On watching at close range the groping of so many workers over centuries toward an unobjectionable proposition, it seemed natural for Duhem to gain the impression of being in the presence of a superior plan of which the individual workers, perfecting this or that stone of a huge edifice, did not have cognizance. Believing as he did in evolution, organic and intellectual, but imbued sufficiently with logic not to be trapped by the magic of blind chance, Duhem conjured up, with no trace of embarrassment, not only the id6e directrice, which for Claude Bernard was a reality, though not physical and chemical,55 but also the sole factor which alone could make that reality meaningful:

 

52. Les origines de la statique, 2:278-79.

53. Ibid., p. 282. Such a powerful metaphor, to say nothing of other encomiums heaped by Duhem on Leonardo, was hardly put in balance by A. Koyr~, according to whom Duhem wanted to turn Leonardo ‘into a trendy medieval’ (see his Etudes d’histoire de Ia pense~e scientifique [Paris: Presses Universitaires de France, 19661 ,p. 90).

54.Lesoriginesdelastatique, 2:286.

55. Ibid., p. 289. Duhem had in mind section 1 of ch. 2 in Part II of Bernard’s Introduction ti l’etude de la me~decine expdrimen tale (1865), where the ‘guiding idea of vital evolution~ is described as a factor which ‘is essentially of the domain of life and belongs neither to chemistry nor to physics nor to anything else’ (see English translation by H. C. Green,An Introduction to the Study of Experimental Medicine [1927: New York: Dover, 1957], p.93). Bernard’s dicta on ‘guiding force’ must have been all the more to Duhem’s liking, because Bernard denied to that force, just as Duhem did to metaphysics in physics, any direct role in biological investigations: ‘Certainly a special force in living beings, not met with elsewhere, presides over their organization; but the existence of this force cannot in any way change our idea of the properties of organic matter, — matter which when once created, is endowed with fixed and determinate,physico-chemical properties’ (ibid.,p. 202).

 

390

 

Across the complex facts which compose this development we perceive the continued action of a Wisdom which foresees the ideal form toward which Science must tend and of a Power which makes converge toward that goal the efforts of all thinkers. In a word, we recognize there the work of Providence.56

 

On October 26, 1905, when Duhem wrote the concluding words of his Origines de la statique, two and a half years after he started work on its first installment, he had already been more than half way through the eight installments in the Bulletin Italien forming much of the first volume of his Leonardo studies. At the very start of the first installment he showed full awareness of the fact that his concept of scientific history was diametrically opposed to fashionable ideas which, as described by him, are also a graphic portrait of presently prevailing fashions:

 

The history of science is distorted by two prejudices, so similar to one another that they could be fused into one: the current thinking is that scientific progress is made by a sequence of sudden and unforeseen discoveries. It is, according to general belief, the work of geniuses who have no precursors at all.57

 

The objection that there was no point in wasting attention on Leonardo’s forerunners, since they all lived ‘in the obscure Middle Ages,’ could easily be dealt with if one was truly an evolutionist as Duhem was: ‘If the branches of the oak are so vast and if its foliage has so much freshness, it is only because the roots, vigorous and numerous, though hidden to the eye, obtain from the deepest soil the juices stored by the old vegetation. Those roots are visible to those who do not shun the labor of tilling the soil.’58 Continuity was the principal lesson drawn from the comparison in the third installment, a comparison of the manuscripts of Leonardo with the writings of Villalpand: The study, Duhem wrote, ‘narrow as it is in scope, is capable of discrediting some of the prejudices which distort the history of the scientific renaissance.’59 One prejudice, which ascribed absolute originality to Leonardo, was countered with the words: ‘Brilliant and solid link as Leonardo was, he takes his place in the chain of scientific tradition.’60 As Duhem analyzed the influence of Baldi, another author of the same epoch, on Descartes and Roberval, another and more generic prejudice was contradicted with the phrase: ‘Science, no more than nature, makes no brisk jumps.’6t

With the sixth and seventh installments published in April and July 1906 Duhem discussed for the first time the influence on Leonardo by Themon, Son of the Jew, an incisive teacher at the Sorbonne in the mid-fourteenth century, whom Duhem practically rescued from complete oblivion. In Themon’s commentaries on Aristotle’s Meteorologica Duhem noticed remarks on hydrostatics which mark

 

 

56. Les origines de la statique, 2:290.

57. Etudes sur Ldonard de Vinci, 1:1.

58. Ibid., p. 2.

59. Ibid., p. 85.

60. Ibid., p.123.

61. Ibid., p. 156.

 

 

 

391

 

edly anticipated some of Leonardo’s dicta. Duhem was able to notice much more than that. The flow of information to Leonardo resembled a brook with several branches in the same way as did the flow from Leonardo to Pascal.62 Once united in a great mind those branches formed a powerful stream whose impact then became obvious everywhere. The eighth installment, devoted in part to Cardan’s plagiarism of Jordanus de Nemore, was far less important than the first of two concluding chapters not published in the Bulletin. There, on the basis of careful studies of several medieval manuscripts of the science of weights, Duhem postulated the existence of a disciple of Jordanus, no less a genius than his master, whom Duhem called the precursor of Leonardo.63 Duhem was very likely wrong, but if he erred it was not because he did not go to great lengths in studying elusive records. He never boasted of the immense efforts and expertise needed for pioneering the study of medieval science. He worked with no help from an army of graduate students and secretaries, with no photocopying machines, dictaphones, not even ballpoint pens, at his disposal. Only when he found out a year later that a decade or so earlier the importance of Jordanus had been set forth by that ‘learned Tuscan priest,’ Raffaello Caverni, in a vast work on the history of experimental method in Italy, did he complain of his condition ‘of a solitary worker in the very poor library of a provincial university.’64 He gave but a hint of his immense labors as he remarked on the garbled reading by an associate of Tartaglia of the manuscript containing the ‘Precursor’s’ thought. In rendering the text faithfully Duhem’s intension was not to display a mastery of minutiae. The test had an importance of its own: ‘This short passage in itself greatly deserves to command the attention of the historian of science. For the first time since men considered questions of

 

62. Ibid., p. 220.

63. Ibid., p. 263.

64. Ibid., 2:361. Whatever advantages the library of the University of Bordeaux had with respect to Lille, let alone to Rennes, the 343,129 volumes it contained as of January 1,1922 (see p. 6 of the brochure, ‘La biblioth6que universitaire de Bordeaux’ [Bordeaux: G. Delmas, 1922; an extract from the April 28, 1922 issue of the Sud-Ouest e’conomiquel by the director of the library, H. Teulai) were distributed over the many areas of interest represented by the faculties of letters, science, law, and medicine, and provided only a limited help to Duhem’s very specialized research, In the Fall of 1903, when Duhem first asked for a medieval manuscript to be sent to the University Library of Bordeaux from the Biblioth~que Mazarine, his request was denied. He obtained the manuscript five months later, in March 1904, after his rector, Bayet, called the attention of the Ministry of Public Instruction to the impropriety of depriving of source material a corresponding member of the Institut. Only after this ddmarche were Duhem’s further requests promptly honored. As to the six volumes of Caverni’s Storia del metodo sperimentale in Italia (Florence: G. Civelli, 1891-1900), the lack of proper organization and thorough interpretation of its storehouse of data was a reason for its not being widely read in scholarly circles. It was not reviewed in the leading French journals of historical studies. The first three volumes of Caverni’s work were so exclusively limited to the description of instruments (vol. I), to branches of physics different from mechanics (vol. II), to medicine and botany (vol. III), that its readers could hardly be expected to look forward to anything relating to the pre-Galilean, let alone to the pre-Leonardo history of mechanics, treated in vol. IV. There (pp. 2 1-26) Caverni based his discussion of Nemorarius’ ideas on a manuscript printed, as one could expect, with no great care by Petrus Apianus in 1523.

 

 

 

392

 

mechanics a magnitude of a connecting force is determined by an exact method.’ His vast perspective as a historian made Duhem look beyond the fact, however important in itself: ‘How much more this passage will command our attention when we shall have greeted the discoveries which it will suggest to Leonardo!’65

The second additional chapter, and the last in the first volume of the Leonardo studies, was devoted to a survey of the writings of Albert of Saxony. ‘The list,’ Duhem concluded, ‘is very likely incomplete. It suffices however to give an idea of the intellectual activity of this great philosopher to register the popularity which he enjoyed at the start of the Renaissance, and finally to combat the unexplainable oblivion where he is left by those who are interested in the progress of human thought in the course of the Middle Ages.’66 Duhem’s work challenged admirers of the Middle Ages no less than the devotees of the Renaissance. The challenge was above all a challenge to posterity, In the preface which Duhem wrote on July 27, 1906, to the first volume of his Leonardo studies, there is a paragraph which should strike today with its modernity (and With its moderation!) all those who take the notion of biological struggle. for survival for an (let alone for the) explanatory device of the history of scientific ideas and pride themselves on originality. ‘The mind of Leonardo,’ Duhem wrote,

 

into which there fell this seed of [newl ideas was not at all simliar to a razed and bare terrain. Other thoughts, vigorous and insistent, had aiready occupied it. They were implanted there by the lessons of the masters, whom Leonardo listened to, and especially by the teaching of the writings he meditated upon. To germinate and to grow, it was necessary that the newly-arrived seed should make use of an already developed vegetation or even to struggle against it.67

 

The placing of Leonardo at mid-point of a sequence of authors ‘whom he has read and who have read him,’ to recall Duhem’s priceless phrase, was the move of a convinced evolutionist, though of the kind of evolutionist mindful of the supreme challenge posed by evolution. That challenge is the securing of what endures in the process of change. Thus for Duhem evolution did not stand for a series of haphazard saltations but for the cement which turns mere succession into solid coherence: ‘Between those whom he has read and who have read him, Leonardo stands in his true place. Connected with the past, the learning of which he gathered and on which he meditated, he remains no less attached to the future as one whose ideas fertilized science.’68

In the first additional chapter there appeared, in a brief note, the name of

 

 

65. Etudes sur Le’onard de Vinci, 1:300. Here too Duhem, the historian, seemed to be a disciple of Fustel de Coulanges, according to whom the science of history did not reside in the documents but in the intellect reading them,and who also held that the historian must consider long epochs, lest his narration should degenerate into mere stories (see J. Herrick, The Historical Thought of Fustel de Coulanges lWashington: The Catholic University of America

Press, 19541 ,pp. 79-82).

66.EtudessurLe’onardde Vinci, 1:338.

67. Ibid., p. vi.

68. Ibid., p. vii.

 

 

 

 

393

 

 

Oresme in connection with the idea of the notion of a ‘motus uniformiter difformis,’ the scholastic term for constant acceleration. Duhem was already in the grip of the potentialities of an exploration of medieval writings on dynamics.69 His plan of writing the origins of dynamics along lines similar to his Origines de la statique began to take concrete form. His daughter, then only fourteen, heard her father speak of such plans.70 With Duhem, plans were as a rule quick steps to actual execution, but Leonardo represented a material too rich to part with quickly. His writings offered ample material for a second volume which dealt with his reflections on the infinitely small and the infinitely large, on the plurality of worlds, together with his indebtedness to Nicholas of Cusa, and with his pioneering the modern science of geology. The broad scope of the Leonardo studies permitted Duhem to move at ease back and forth between the 13th and the 17th centuries, but in all these moves Leonardo remained the center. Leonardo, wrote Duhem in the preface he penned on January 12, 1909, to the second volume, ‘sums up and condenses so to speak in his person all the intellectual conflict through which the Italian Renaissance becomes the inheritor of the Parisian scholasticism.’71

 

The source of continuous growth

Continuity was the gist of Duhem’s view of history, but because he viewed that continuity as something living he had eyes for the struggle and delayed outbursts of new growth, characteristic of all life. Above all he had an eye for the all-important question about living continuity, namely, its vital beginning. The preface of the second Leonardo volume contained two phrases which by their conspicuous place must have struck the eyes of all readers, In the first Duhem spoke of ‘Christian thought, which at the end of the thirteenth century broke the tyranny of peripatetic philosophy.’ In the second he referred to the contact made during the sixteenth century by Italian thinkers with ancient Greek geometry, which made them more receptive to the teaching of the Parisian masters of the 14th century:

‘The contact infused into them a new life of which the renaissance of science is a witness.’72 Few readers went as far as Note F in the end of the book, where Duhem discussed the medieval break with the Aristotelian opposition to the plurality of worlds, or more specifically, to the infinity of ‘worlds’. The break, which ultimately made possible the formulation of the concept of linear inertia, was of utmost importance for the future of science. Even more important had therefore to appear the force, Christian awareness of the Creator’s unlimited powers, which made that break possible. This is why Duhem accorded decisive symbolic significance

 

69. Attested by his long essay, prepared for the Second International Congress of Philosophy (Geneva, Sept., 1904) and published two years later, 1906 (25). In that essay Duhem still moved almost directly from the Greeks to Leonardo de Vinci. He, however, assumed that at least some scholars in the 13th century held the notion of ‘impressed motion’ because of Aquinas’ criticism of it; see especially pp. 867-68.

70. Un savant fran~ais,p. 191.

71. Etudes sur Le’onard de Vinci, 2 :iv.

72. Ibid., pp. iii-iv.

 

394

 

to the condemnation on March 8, 1277, by Etienne Tempier, Bishop of Paris, of 216 propositions, among them the one denying the possibility of the plurality of worlds. Duhem felt that ‘if we were to specify the birthdate of modern science, we would undoubtedly choose that year, 1277.’73 Such was the debut of a phrase, which he was to repeat emphatically in evidence of the importance he attributed not so much to a mere date but to the question of live birth, the fundamental precondition of all continuity, including the continuity of growth, be it biological or intellectual.

These three phrases anticipated the gist of the third volume of the Leonardo studies, possibly the most dramatic volume ever published on the history of science. Its more than 600 pages were reserved for the birth and transmission of two pivotal notions of physics, the law of the conservation of momentum and the law of free fall. The former saw birth under the name of impetus in the commentaries of Buridan to various works of Aristotle, a chief advocate of the eternity of the world and its motions. Aristotle was also the originator of that concept of motion in which the mover had to be in continuous contact with the thing moved. Hence, in the Aristotelian discourse the Prime Mover (not unambiguously distinct from the world) had to remain in contact, however intellectualized, with the outermost of the heavenly orbs in order to secure the motion of all celestial bodies and through them all motion below the moon’s orb. To part with such an explanation of motion demanded the recognition of the absurdity of the claim that, say, the flight of a projectile was due to the push of the air which closed in behind it almost as if somebody was to lift himself by his own bootstraps. No less needed was a shift in broader cosmological outlook concerning the very source of motion. The Christian view of creation provided that shift and also provided Buridan with his favorite account of the start of all physical motion. Buridan was fully aware that the view very much moulded his reflections. It was also a view which withstood any rational objection that reason could think of:

 

There is a view which I never could refute in a convincing manner. According to that view, from the very moment of the world’s creation God made the heavens move with motions identical to the ones with which they still move. He impressed on them various impeti in virtue of which they continue to move with uniform velocity. As these impeti do not in fact encounter any resistance which would oppose them, they are never destroyed or diminished.74

 

 

The crucial importance of this new cosmic outlook was not lost on Duhem. He wanted the reader of the third volume of his Etudes to be ready for a drama as soon as he started reading the Introduction to it: ‘If one wanted to separate with a

 

73. Ibid., p. 412. The statement forms part of Note F. In the previously unpublished essay, ‘Leonard de Vinci et la pluraliai des mondes,’ which forms ch. 2 of the volume, Duhem discusses (pp. 75-82) in detail the various propositions condemned by Tempier without,however, attributing to his decree an epoch-making significance.

74.Etudes sur Ldonard de Vinci, 3:52. The importance attached by Duhem to that passage

can be seen from his quoting it also in the Preface of that volume (p. ix).

 

 

 

395

 

 

distinct line the reign of ancient science from modern science, one should trace that line to the moment when John Buridan conceived that theory; to the moment when one ceased looking at the planets as beings moved by divine intelligences; to the moment when one admitted that celestial and sublunary motions rested on the same mechanics.’75 A mere dozen years after a horizontal line, standing for a contemptuous recall of the presumed ignorance of medieval centuries, appeared in Wohlwill’s account on the history of the law of inertia, there emerged another line cutting across the former. The new line witnessed to a genuine science in those centuries and symbolized a new vision. That line was also to separate true scholarship from well-worn cliches.

Duhem’s account of the pre-Galilean history of the law of free fall was no less dramatic. Here too he was meticulous for details such as the lack of connection for over two centuries between two propositions: one about the velocity in uniformly accelerated motion, the other about the velocity as a function of time in free fall. But he also served evidence that by the time the Spanish Dominican, Domingo de Soto, educated in Paris, put in print around 1560 for the first time the correct law of free fall as a case of uniformly accelerated motion, the law seemed to have been common knowledge in Paris and elsewhere. Moreover, Duhem served evidence that Galileo was fully cognizant with the works of the 14th-century ‘Parisian doctors.’76 Such was the background of that declaration of his which is still to make its appropriate impact: ‘While in support of these two propositions Galileo will be able to submit new arguments drawn either from reasoning or from experiment, he will not in the least need to discover them.’77

No declaration ever made by a historian of science was more dramatic, bolder, more justified and yet so much resented or ignored. Yet, Duhem was only true to that balanced view of history in which continuity is the primary truth and the supreme standard of the recognition to be accorded. Thus he still could speak of the genius of Galileo as the one who, although not a discoverer of the law itself, provided the first geometrical (mathematical) proof of it and also, unlike his medieval forerunners, an experimental verification of the law: ‘The Pisan arrived at the proper moment; . . . ripe ideas waited for a geometer of genius who would put in full light the truths living in them and who would launch the science of mechanics of modern times. Galileo was that geometer.’78 Never in his admiration of the Middle Ages was Duhem a begrudger of Galileo’s glory. He merely wanted, as befitted a historian respectful of fact, that glory to be free of the spurious resplendence of a sheer myth concocted for patently non-scientific purposes.

In the summer of 1910, when Duhem wrote those lines to be ready for the

 

75. Ibid., p. ix.

76. Ibid., p. 582. The correctness and significance of Duhem’s drawing attention to those references to the ‘Parisian doctors’ in Galileo’s early writings were amply demonstrated by recent studies, especially by those of W. Wallace; see, for instance, his ‘The Enigma of Domingo de Soto,’IsisS9 (1968):348401.

77.EtudessurLe’onardde Vinci, 3:562.

78. Ibid., p. 259.

 

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January-March issue of the Bulletin Italien, he had been engaged for six years in a heroic pioneering study of the history of science in medieval and Renaissance centuries. He had six more years of work allotted to him, as he would have certainly put it, by Providence. His balanced view of Galileo’s genius was, contrary to a rather slanted claim, not the product of his final and mature view, a sort of retraction.79 As a historian, no less than as a philosopher, Duhem showed a surprisingly high degree of ‘maturity’ at a relatively early stage of his investigations —physical, philosophical, and historical. Nor was maturity ever lacking in his appraisal of the role of Christian creed and dogma in the rise of modern science. Of course, against the dark background produced, propagated, and imposed as a dogma since Francis Bacon and Condorcet agreed — for distinctly different reasons

— that Catholicism in particular and Christianity in general were sworn enemies of learning and science,80 any rejoicing over the medieval contribution to the rise of science could but appear in established circles an immoderate overreach, nay a sheer sacrilege, not to be tolerated.

Silence, as will be seen, has been one favorite weapon in this respect. Another has been the labeling of Duhem’s interest in history as a thinly disguised apologetics to which scholarship is subordinate. There is no trace in Duhem’s writings of such motivation whatsoever. His overriding interest was the completeness of the image of physical science. Nothing was, of course, more natural for him than to realize the broader significance of the emergence of science during the Middle Ages in virtue of Christian thought. Such a truth struck at the root of scientism, the unofficial ideology of the Third Republic, In the opening decade of this century, no less than today, the gullible public, including its academic sector, readily swallowed any claim, however unrelated to science and however unfounded, if offered in scientific wrapping. Dismissal of Christianity as an enemy of science and reason is still a chief strategy of her opponents, violent and polite. Only in this light will appear the true physiognomy of the resentment which in certain circles is still provoked by the rejoicing of Duhem, the historian of science, who neither mixed his Catholicism into his historical research, nor was ever ashamed of it. At any rate, unlike many modern historians who try to hide their agnosticism, if not their militantly anti-christian outlook, under the cloak of ‘scholarly objectivity’ free of metaphysical presuppositions, Duhem was here too sincerity itself. Indeed, a Christian sincerity was needed that the fight of the Sorbonne during the 14th century on

 

79. A claim of E. Rosen, ‘Renaissance Science as Seen by Burckhardt and His Successors, in T. Helton (ed.), The Renaissance: A Reconsideration of the Theories and Interpretations of the Age (Madison: University of Wisconsin Press, 1961), p. 96, based on two rather transparent tactics. One is Rosen’s keeping his readers in the dark about the fact that at most three years separate the publication of the third volume of the Leonardo studies from Duhem’s writing of what became the tenth volume of the Sysr~nme du monde. The second is Rosen’s implicit suggestion that Duhem, who died at the age of 55, was not mature yet as a historian at the age of 52, after ten years of monumental and pioneering researches. More on the motivations of such tactics later; see also note 87 below.

80. For details, see ny The Origin of Science and the Science of its Origin, pp. 7-12 (on Bacon) and pp. 36-39 (on Condorcet).

 

 

 

 

 

 

397

 

behalf of Catholic orthodoxy be recognized as the source or matrix out of which there emerged the epoch-making insights of a Buridan and an Oresme, And the sincerity of a Christian was needed to add that concluding note in the Preface Duhem penned on May 24, 1913, to the third volume of his Leonardo studies:

‘And how could a Christian not give thanks for this to God!’81

 

Scholarship as apologetics

Or was a Christian, a Catholic, to remain forever silent about attacks on Christianity based on scientific history? As today, so in Duhem’s time, some of those attacks were so many rhetorical exercises in pages reputedly reserved for scholarly exposition. G. Milhaud, future occupant in Paris of a chair created for intellectual history in reference to science,82 proved his unfamiliarity with the ‘latest’ (the first volume of Duhem’s Origines de la statique published in 1905), as he wrote in 1906 that ‘if the art of printing had been invented two centuries earlier it would have especially served the reinforcing of orthodoxy and the propagation of the Summa of St. Thomas and works of that kind, in addition to the bulls of excommunication and the decrees of the Holy Office.’83 It was not ‘apologetics’ on Duhem’s part but plain intellectual honesty based on an enormous grasp of factual evidence that made him write in 1913 with a view on Milhaud’s dictum: ‘If the art of printing had been invented two centuries earlier, there would have been printed, at the rate as they were written, the works which on the ruins of the physics of Aristotle, laid the foundations of a mechanics of which modern times are justly proud.’84

Only because he was in command of a vast array of facts gathered with no apologetical motivations (which, even if covert, should seem to call for no apology whatever when aimed at the unearthing of facts), did Duhem feel justified in using the history of science for Christian apologetics. Indeed he urged that such a use be made of it. The major document in this respect is Duhem’s letter of May 21, 1911, to the Nre Bulliot, professor of philosophy at the Institut Catholique in Paris, The two, who had known one another for years, met on May 14 while Duhem visited Paris. Their conversation must have dealt a great deal with the relevance of the philosophy and history of science for an effective presentation of Catholic truth. The P~re Bulliot must have been deeply impressed because next day he asked Duhem in a letter to put in writing his ideas on the subject.

 

 

 

 

 

81. Etudes sur L6onard de Vinci, 3 :xiv.

82. The chair was established in 1908 for the Sorbonne.

83. G. Milbaud, Etudes sur Ia pen se’e scientifique chez les Grecs et les modernes (Paris:

Soci6t~ fran~aise d’imprimerie et de libraiie, 1906), pp. 268-9. The statement was part of ‘Science grecque et science moderne,’ the last of Milhaud’s previously published essays reprinted in that volume.

84. Etudes sur Ldonard de Vinci, 3 :xlii.

 

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Duhem quickly complied with a long letter,85 much more than a plea for the establishment in the philosophy department of the Institut Catholique of two chairs, one for the philosophy of science, another for the history of science. Such chairs, Duhem argued, could greatly help to counter at its nerve center the strategy of the opponents of Church and Christianity. The strategy, Duhem argued, was no longer about particulars, say, the agreement of this or that biblical verse with the findings of geology, but about fundamentals which determine the outcome of any and all debate. The fundamentals related to two major fields. One was the logical analysis of scientific knowledge as the only one which provides certainty. The other was a portrayal of intellectual history centered on the growth of science as the sole embodiment of rationality. ‘As one living among those who profess doctrines contrary to ours and therefore well placed to know their plan of attack against us,’ Duhem called the Nre Bulliot’s attention to the fact that both fields were exploited in order ‘to deny, in the name of science as such, to all religion the very right to exist.’ The strategy, whatever its intrinsic merit, found steady support in the fact that ‘the value of science further asserts itself every day through thousands of marvelously useful inventions which only a blind man would call into doubt.’

The logical analysis of scientific knowledge was used either to advocate radical positivism for which ‘the object of religious dogmas is absurd and void of sense,’ or to advocate agnosticism which views the same object ‘as one which escapes the demonstrations of science and is therefore incapable of being known with the slightest [degree of] certitude.’ In the latter case, Duhem noted with striking anticipation of claims made by many philosophers and historians of science, one is asked ‘to subscribe to an agnosticism for which all religion is a dream, more or less poetical and comforting.’ Needless to say, they would also add that such a comfort was unworthy of a mind ‘which had experienced the firm realities of science.’ Moreover they would relentlessly resort to the historical argument:

 

They show us how all the sciences are born of the fertile Greek philosophy whose most brilliant exponents left to the vulgar the ridiculous concern of believing in religious dogmas. They depict to us shockingly that night of the Middle Ages during which the schools, subservient to the agencies of Christianity and exclusively concerned with

 

 

 

85. The full text of that letter is given in Un savant fran~~ais, pp. 158-69. In his letter of May 15, 1911 to Duhem, the P~re Bulliot expressed his hope that the pattern to be set by the Institut Catholique in emphasizing the teaching of the history and philosophy of science would be quickly followed by Catholic universities outside France, a hope still to be largely fulfilled. In thanking Duhem for his long letter, the P. Bulliot informed Duhem that his recommendations had been quickly acted upon by the P. Peillaube in the form of a long memorandum to the authorities of the Institut Catholique and that a copy of it had been sent confidentially to him. The P. Bulliot also expressed his regret that Duhem was the only one missing in ‘the little cenacle of Clamart [a village 8km southwest of Paris on the edge of the Meudon forest l~ a replica of the cenacle in the Montagnes Noires,’ a nostalgic allusion to some summer gatherings already described in Chapter 6.

 

 

 

 

 

 

399

 

theological discussions, did not know how to gather the smallest parcel of the scientific bequest of the Greeks. They make shine into our very eyes the glories of the Renaissance where minds, liberated at long last of the yoke of the Church, have found again

the thread of scientific tradition at the same time as they found the secret of scientific and literary beauty. They delight in contrasting from the 16th century on the always ascending march of science, the ever deeper decadence of religion. They believe themselves to be authorized to predict the imminent demise of religion and at the same time the universal and unchallenged triumph of science. This is what is being taught in a number of chairs, this is what is being written in a multitude of books.’

 

What sort of a reply was called for by such claims? The reply Duhem spelled out

was that of an academic unafraid to vindicate truth from fallacy:

 

In the face of that teaching it is time that the Catholic teaching rise and hurl into the eyes of its adversary this word: lie! Lie in the domain of logic, lie in the domain of history. A teaching which pretends to have established the irreducible antagonism between the scientific spirit and the spirit of Christianity is the most colossal lie and the most audacious which has ever attempted to dupe the people.

 

As to the abuse of the analysis of knowledge Duhem stressed the unity of human intelligence, The same mind was at work in various fields although each of them required different presuppositions and objectives. Once this was recognized across the mathematical, experimental, and historical disciplines, it would easily be seen that the specificity of religious knowledge was but another variation on the same intellectuality. As to the portrayal of history on behalf of a narrow-minded analysis of scientific knowledge, Duhem started with a reference to the conditioning of Greek science, from its very birth on, by pagan theology. The various tenets of that theology, including the divinity of the heavens and the uncreatedness of the universe, proved in the long run so many harnesses preventing free intellectual movement and growth. ‘If the human mind had not broken these harnesses, it would not have passed beyond Aristotle in physics and beyond Ptolemy in astronomy,’ wrote Duhem, who could recite a long list of conceptual breakthroughs made in the Middle Ages as his answer to the questions: ‘Who broke these harnesses? Who had first profited from the freedom thus gained in order to launch forward to the discovery of a new science?’ The inference was blunt in its plainness: ‘If therefore that science, of which we are so legitimately proud, could see birth, it was only because the Catholic Church was its midwife.’

If such was the case, the establishment of two chairs, one for the philosophy

of science, another for the history of science, had to be of paramount importance

for the Institut Catholique or for any Catholic institution of learning:

 

The chair devoted to the analysis of the logical methods by which the various sciences make their progress, would show us that one can, without contradiction and incoherence, pursue the acquisition of positive [scientific] knowledge and, at the same time, meditate on religious truths. The [instruction given from the] other chair would, by following

the historical course of the development of human knowledge, lead us to recognize that in times when men were intent above all on the Kingdom of God and of His justice, God gave them for good measure the most profound and seminal thoughts concerning things of this world.

 

400

 

The proposition may have appeared daring to many though not to Duhem whose ‘sole concern’ in the matter was ‘to see the Kingdom of God re-established among us’ and who held that he dealt with an ‘objective on behalf of which there was no daring which would not only be permissible but very much in order.’

Nothing would be more misleading about Duhem than this letter if read either with the sanguine eyes of a facile Christian apologist or with the resentful mind of someone bent on keeping science harnessed in the service of unscientific aims. None of Duhem’s writings comes even remotely close to apologetical (or counterapologetical) writings, a genre very much in vogue at that time. At College Stanislas, at the Ecole Normale, and in Lille, Duhem, as was already noted, stood apart from such involvements. He worked out a philosophy of physics to satisfy himself as a physicist. That such a philosophy could be useful for countering the claims of scientism was not something that motivated his work. For years he accepted with no discomfort the standard view of the history of science according to which there was nothing between the Greeks and Descartes. Not in the slightest did he espouse, as he wrote his Evolution of mechanics and the first installments of his Origines de la statique, anything of inept apologetic efforts which in the second half of the nineteenth century tried to rehabilitate scientifically the Middle Ages.86 Only rank prejudice would see in Duhem’s celebrated series of essays, To Save the Phenomena, a work motivated by the desire to undercut once and for all the anti-Catholic exploitation of the Galileo case. Duhem’s interest in the motto, ‘to save the phenomena,’ was born out of his wrestling, while in Lille, with the nature of physical theory as an explanation. It was most natural for him to become interested in the whole history of that motto after it had become very clear to him, following his encounter with the writings of Jordanus Nemorarius and with the complex history of Leonardo the scientist, that large segments of scientific history were missing in the standard accounts.

 

The quest for completeness

To restore the completeness of the record was enough of a motivation for Duhem to write that famous essay. Historical completeness was a test of the truth of his theory of physics. Since it was the essence of physical science to be mathematical, the truth of physical theory, Duhem noted,87 could not be illustrated from medieval physics which for all its insights remained essentially qualitative, even its science of weights, the discovery of which enthralled him so much. Quite different was the case with astronomy. It was the only part of physical science which already in the hands of the Greeks achieved a mature degree of exact, that is, quantitative treatment. In this special status of astronomy Duhem saw a major proof of his

 

86. The schoolman most often seized upon in that respect was Albert the Great, who was turned into the initiator of the experimental method by F. A. Pouchet, professor of zoology at Rouen, in his Histoire des sciences naturelles au Moyen Age ou Albert le Grand et son e’poque considdre’s comme point de de’part de l’dcole expe’rimentale (Paris: J. B. BailWere, 1853).

87. To Save the Phenomena, 1969 (1), p. 3. This remark of Duhem should suffice to lay bare the hollowness of Rosen’s claim discussed in note 79 above.

 

 

 

 

 

 

401

 

principal contention that physical theory was not an explanation but a quantitative systematization of data and that physical science advanced most when its cultivators have seen physical theory in such a light.

While this last point could readily be argued with respect to Ptolemy, whose system was not surpassed in accuracy by the heliocentrism of Copernicus, the latter, and especially Kepler and Galileo, to all of whom Duhem referred as ‘Renaissance astronomers,’ was a different matter. Could it be shown that their great achievements were done in virtue of the purely formalist motto, ‘to save the phenomena,’ in spite of their formal opposition to it, and in spite of the ‘realism’ to which they subscribed in the belief that physical theory was an explanation? It was this question which Duhem tried to answer by setting forth the history of that motto on a scale that went well beyond the level to which scholars like T.H. Martin, G. Schiaparelli, and P. Mansion, all of whose help Duhem generously acknowledged, had carried it.88 Being fully conscious of why he was undertaking the history of that motto, he could benefit in full from the insights which that meaning, as he saw it, provided. The meaning enabled him to be eminently fair to the ‘Renaissance astronomers’ in spite of laying bare the superficiality of their ‘realism.’ It was not so much a realism based on common sense as the ‘realism’ of a spurious reification of geometry. (Galileo was too poor a ‘realist’ philosopher to realize the disastrous consequences for his ‘realism’ which followed from his rejection of the reality of secondary qualities.) Since a pivotal part of Duhem’s theory of physics was that it should rigorously and consistently account for all phenomena, his story could end as an eccomium of ‘Renaissance astronomers.’ For, as Duhem put it, what the Renaissance astronomers, in spite of their spurious realism, were really requiring was

 

that the theory of the celestial motions rest upon bases that could support the theory of the motions we observe here below as well. The courses of the stars, the ebb and flow of the sea, the motion of projectiles, the fall of heavy bodies — all were to be saved by one and the same set of postulates, postulates formulated in the language of mathematics . . . Despite Kepler and Galileo, we believe today with Osiander and Bellarmine that the hypotheses of physics are mere mathematical contrivances devised for the

purpose of saving the phenomena. But thanks to Kepler and Galileo, we now require

that they save all the phenomena of the inanimate universe together.89

 

 

Today when the equivalence of all reference systems is part and parcel of thinking in physics, the position of Osiander, Bellarmine, and Urban VIII appears far more than a poor defensive tactic of embattled theologians. In 1908, when Duhem wrote those words, Einstein’s relativity still had to assert itself. Hence Duhem’s

 

88. Their studies were of help to Duhem only in the first chapter dealing with hellenic science. For the remainder of the work — another six chapters dealing with the views of Arabic, Jewish, Scholastic, and Renaissance astronomers up to Galileo — his sole help was the Bibliographie gdndrale de l’astronomie (1887) by Houzeau and Lancaster. He was indeed most entitled to point out that ‘to the texts which they [Martin, Schiaparelli, and Mansion] brought to attention we shall be adding a good many others’ (ibid., p.4).

89. Ibid., pp . 116-17.

 

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insight and articulation should seem all the more impressive and daring. Duhem did not wish to win particular battles. His strategy aimed at the entire dispute between formalists and realists and therefore had to cover the field as completely as possible. Canvassing the story from Plato to Copernicus issued in the ten volumes of the Syst~’me du monde and seems to have called for superhuman forces as its almost six thousand pages, bursting with material of astonishing richness, were written in a mere eight years that were not exclusively set apart for the undertaking. Aiming at completeness implied attention to all facets of the process under investigation, and therefore to its slowness, a principal facet if the growth was genuine, that is, organic. Thus Duhem took for the motto of the whole work a dictum of Roger Bacon: ‘Never was any science invented at any particular time, but from the beginning of the world knowledge has grown slowly and is still not complete at this very age.’90

Since Duhem’s interest in the history of physical science was a function of his philosophy of physics, it should not be surprising that the Syst~me du monde was from its first volume on a mine of information on the philosophies of those who discoursed on scientific matters from the time of Plato. The first two volumes of the Syst~me dealing with the evolution of cosmology in classical antiquity from Plato to Philoponus would have done credit to a historian of Greek philosophy. The same volumes are still among the best accounts, and in a specific sense the very best account, of cosmological science in Hellenic and Hellenistic antiquity. Duhem’s treatment of the subject was steeped in the belief that all science was a function of a world view. This is why Duhem devoied so much space to the question of tides as discussed by ancient Greek authors.91 For it was there that came most conspicuously to the fore within a scientific context the intellectually hopeless entanglement of the ancient Greek world view in astrological lore. There the specific sense in which the ancient Greeks attributed unity to the world of things, also came fully to the fore. While the attribution of unity is at least an implicit requirement of any meaningful scientific work, the sense in which such an attribution is made is of decisive importance for the true quality of that work. The unity of all was for the Greeks the unity of a living organism. For them the world was an all-encompassing living entity, a view codified by Plato and Aristotle. Such a world view, in which everything was connected with everything as so many members of one living body, invited Aristotle’s definition of motion that the mover and the moved had to be in continuous contact with one another during the whole duration of motion. Astrological discourse was part and parcel of that organismic view of the world which made the formulation of a correct science of dynamics impossible. Astrological preoccupations, so many threats to human freedom, including the freedom of inquiry, infiltrated and corrupted all scientific discourse

 

 

90. Duhem’s admiration for Roger Bacon sharply contrasted with his strictures of Francis Bacon as one who did not understand a thing about the experimental method while singing its

praises (Syst~me du monde, 3:440).

91. Ibid., 2 :266-390.

 

 

 

 

 

 

403

 

 

whenever that discourse went beyond geometry or a purely geometrical astronomy to such topics as the tides. Thus in the same contexts, where the tides were spoken of as the effect of the mutual pull between two material bodies, the earth and the moon, there was the ubiquitous presence of the astrological exploitation of an idea which could in itself have propelled ancient Greek thought toward the recognition of universal gravitation and its mathematical formulation. The ancient Greek mind, for all its excellence in the sciences, which Duhem portrayed with astonishing mastery and detail, especially with respect to astronomy, could not free itself of the mirage of an astrological and organismic world view. The latter received its supreme expression in the doctrine or system of the Great Year. To make one of the greatest discoveries of all times, the recognition by Hipparchus of the precession of the equinoxes, subservient to that system, was taken for a meritorious task by all schools. Or as Duhem brought to a conclusion the over 900 pages he devoted to ancient Greek science:

 

To the construction of that system all disciples of Hellenic philosophy — Peripatetics, Stoics, Neo-Platonists — contributed; to that system Abu Masar offered the homage of the Arabs; the most illustrious rabbis, from Philo of Alexandria to Maimonides, have accepted it. To condemn it and to throw it overboard as a monstrous superstition, Christianity had to come.92

 

Against this background it made eminent sense to discuss, as Duhem did in a way of a long conclusion to the second volume of the Syst~me, the manner in which the Church Fathers reacted to the philosophy and science of pagan Greek teachers. Looking at it superficially, the manner was puerile and obscurantist on the part of not a few Fathers eager to vindicate the letter of the Biblical story of creation. Even more obscurantist would their attitude appear if viewed through scholarly sourcebooks on Greek science which readily give the impression that there traversed through the centuries of classical antiquity a tradition of ‘pure science’ untainted by any form of obscurantism. To be sure, in the dicta of the Fathers there are not lacking gems of ‘enlightened reason,’ such as Augustine’s warning that, since the heathen can know a number of things about the material world that can be ‘experimentally verified’ and supported by ‘unquestionable proofs,’ the faithful must be on guard against making a laughing stock of themselves and of the Bible.93 Although undoubtedly familiar with that warning, Duhem did not quote it.94 He wrote not apologetics but a history where he never

 

92. Ibid., p. 390. This all-important point, made by Duhem, is further discussed in the context of the first two volumes of the Systi~me in my article, ‘The Greeks of Old and the

Novelty of Science,’ in Aretes mne’me: Aphie’roma eis mndmen tou Konstantinou I. Bourbdre

IVourveris Festschriftl (Athens: Ellenik~ Anthropistik~ Etairela, 1983), pp. 263-77.

93. St. Augustine, De genesi ad litteram, Lib. 1, cp. 19. For English translation of the entire passage, see my Science and Creation: From Eternal Cycles to an Oscillating Universe

(Edinburgh: Scottish Academic Press, 1974), p. 182.

94. In discussing the cosmological stance of the Church Fathers, Duhem quoted three times from the first book of De genesi ad litteram, though not from the 19th chapter; see

Systi~medu monde, 2:436-7 and 492.

 

 

 

404

 

lost sight of the basic issue. It related to the presence, beneath scientific particulars, of cosmologies which, as he put it, were so many theologies.95 The Fathers did not have to be experts on science to oppose and reject those cosmologies and theologies. Yet, by doing so they cleared the ground for a better science and also provided the spark for it. Duhem was not the purist historian afraid of giving a foretaste of the grand conclusion:

 

In the name of Christian doctrine the Church Fathers attacked the pagan philosophers on points which today we judge to pertain more to metaphysics than to physics, such as the theory of eternal prime matter, the belief in the domination of planets on sublunary things, the belief in the periodic life of the world caught in the rhythm of the Great Year. By destroying through those attacks the cosmologies of Peripatetics, Stoics and Neoplatonists, the Fathers of the Church cleared the terrain for modern science ... Modern science, one may say, will be born the day when one wrn dare to proclaim the truth: the same mechanics, the same laws govern the celestial motions and the sublunary motions, the motion of the sun, the ebb and flow of the sea, the fall of bodies. That such an idea may possibly be conceived it was necessary that the stars should be removed from the divine rank where Antiquity had put them; it was necessary that a theological revolution take place. This revolution will be the work of Christian theology. Modern science caught fire from the spark touched off by the clash between the theology of Hellenic paganism and the theology of Christianity.96

 

 

Within that perspective it was no rhetoric to lament the demise of classical wisdom in the very lands which saw its birth and development and to recall the coming of new young nations eager to seize the last and almost dry seeds of that wisdom. Much more was at issue than to bring fresh forces to lands peopled by decadent nations where the power of invention was growing feeble. The soil itself, Duhem warned, had to be reworked to let a new vegetation arise.97

Apart from this view in depth the Syst~me du monde may appear useful only as a storehouse of data to satisfy the precepts of logical positivism according to which everything meaningful must be ‘on the surface.’98 Of course, the Syst~me was bursting with such data. In addition to the long section on tides, its first two volumes are still a first-rate source on each and every discourse of the Greeks of old on homocentric spheres, on heliocentrism, on eccentrics and epicycles, and on the dimensions of the world. The subsequent volumes are bursting no less with ‘positive’ information. The third volume is a still unsurpassed documentation on such a ‘positive’ topic as the medieval reflections on Heraclides of Pontus’ system of the world, a transition between geocentrism and heliocentrism. Duhem did not exaggerate in introducing that third volume with the remark: ‘The desire to learn was intense among the young nations which invaded the Roman Empire.’99

 

 

95. Ibid., p. 453.

96. Ibid., pp.408 arid 453.

97. Ibid., p. 501.

98. As stated in the Manifesto of the Vienna Circle. See Wissenschaftliche Weltauffassung:

Der Wiener Kreis (Vienna: Verein Ernst Mach 1929), p. 15.

99.Syst~me du monde, 3:3.

 

405

 

 

No less intense was his own eagerness to learn and unearth everything possible about that desire. The third and fourth volumes, largely devoted to astronomy as cultivated in various medieval schools — secular clergy, Dominicans, Franciscans, Parisian and Italian doctors — would do credit to any historian of science for whom only positive data are of relevance, The same type of scholar would, of course, be dismayed by the ‘positivist’ Duhem’s resolve to consider the various metaphysical notions beneath the ‘positive’ crust. The second part of the Syst~me, devoted to astronomical theories in the Latin Middle Ages, is followed by a vast discussion of the philosophical layers underlying those ‘positive’ systems, including their most fundamental or metaphysical kinds. But even a historian sensitive to the sweep of metaphysics probably did not guess what was ultimately in store as Duhem declared at the very outset: ‘The dominant ambition of human intelligence is the one which pushed him to comprehend the universe. To know what all things are, whence they come, whither they go, such is the curiosity of infinite amplitude which.., gave birth to philosophy’ 100

Duhem went all the length philosophy called for as he considered first Neoplatonism, mostly transmitted by the Arabs, as one of the philosophies underlying astronomical theories which were discussed during the Middle Ages. Some Arabic commentators of the ‘Theology of Aristotle’, a chief source of Neoplatonism for the medievals, noted a strange contradiction there. On the basis of pure emanationism it was contradictory that a superior being should desire an inferior being and provide thereby its raison d’~tre. In fact the very concern of a superior being about any inferior being turned the former, if the logic of emanationism was strictly followed, into a being less worthy than the inferior being. AI-Ghazzali, the Muslim philosopher-mystic, aware of the dogma of creation which the Koran inherited from biblical revclation, accepted that contradiction. He did so with a reference to the concern of the shepherd for his sheep, of a prophet for his disciples: ‘The shepherd insofar as he is a shepherd [who cares for his sheepi is inferior to the sheep but superior to them insofar as he is a man.’ In commenting on this Duhem went all the length required by the facts of the history of human reflection: ‘Assuredly no philosophy outside the influence of Christianity could make intelligible the benevolence by which the superior being desires, without compromising [his own status] ,the good of the inferior being. No such philosophy could comprehend that the prophet loves his people, that the Good Shepherd loves his sheep to the point of giving his life for them.’t01 A sectarian comment, the ‘non-sectarian’ historian would add in hinting about the presence of a debilitating bias irreconcilable with ‘objective’ scholarship. But is not there more bias in the positivist’s non-sectarianism, professedly in service of all facts, which shuns and positively excludes decisive facts of intellectual history because those facts witnessed an unlimited resolve to understand the world, that is, existence itself?

Not that Duhem was attuned to questions about existence, his commitment

 

 

100. Ibid.,4:309 (italics added).

101. Ibid., 4 :453.

 

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to the primacy of common sense notwithstanding. This is well attested by the fifth volume of the Syst~me, which completes Duhem’s treatment of the growing tide of Aristotelianism during the 14th century. He brings it to a close with Siger of Brabant’s espousal of Aristotle. In Duhem’s rendering, Siger’s stance was an unintended warning that Peripatetic doctrine and Christian faith were irreconcilable. Duhem took the 1277 decision as a heeding of that warning. Christendom had to choose, and Duhem was obviously rejoicing over the choice made on behalf of faith against an unreconstructed Aristotelianism. That these were the real alternatives seemed to Duhem exemplified in Siger of Brabant’s insistence that Aristotelianism demanded from Scholastic Christianity, unwilling to reject Catholic orthodoxy, the admission that two contradictory doctrines could both be true:

‘One because the Church taught it, the other because it was rationally demonstrated by the philosophers.’ But Duhem himself cast the alternative also in a form which he hardly thought over: ‘Christianity was expected to sacrifice either its faith or its common sense. The side was quickly taken by Christianity which sacrificed pagan philosophy.’102 Duhem, a professed apostle of commo