Leonardo's Method · Chapter 12 of 15
10. Historiography
That Leonardo's contributions have never been properly acknowledged is not simply due to limitations in his presentation. It is also a question of fashions in historiography that we need to examine briefly if we wish to re-assess Leonardo's position. For there is more at stake than deciding on the study habits of a well known individual. There is a more fundamental debate on the origins of early modern science: whether there was a gradual evolution from the mediaeval period to the present or whether there was a scientific revolution, a sudden paradigm shift. And as we shall show these debates have become heated because they are no longer about who invented or discovered what or where. They have become debates about method: about the how and why of invention and discovery. And ultimately they are about something even more basic: whether history counts. To understand these developments we need to go back to the nineteenth century.
The history of science as pictured by nineteenth century scientists such as Whewell[374] was straightforward. There was progress and there were great men. The middle ages had basically been a millenium of darkness. Then a genius such as Leonardo brought about a scientific revolution which was carried further by the next genius, Galileo, and so on. This was so obvious that there was no need to document the details of how it had occurred. This view remained largely unquestioned until the autumn of 1903 when Duhem found irrefutable evidence that Leonardo had studied mediaeval sources such as Jordanus of Nemore.[375] Duhem soon stated his case more forcefully: "There is no essential idea in the mechanical works of Leonardo da Vinci which does not derive from the mediaeval geometers."[376] Soon, even sceptics accepted that there must be some continuity between mediaeval and renaissance science, a gradual evolution rather than some sudden event[377]. This evidence was particularly taken up in the United States. Sarton included mediaeval science in his great Introduction[378], while individuals such as Thorndike[379], Benjamin[380] and Clagett[381] founded mediaeval science as a proper field of study. Their studies established that the scope of mediaeval science was much larger than had been assumed, that knowledge of mediaeval sources in fifteenth century Italy was much more widespread than had been imagined. So Leonardo was not alone. But while Duhem concluded that Leonardo had acquired all his ideas from this mediaeval tradition, Clagett decided that Leonardo's knowledge of it was incomplete at best. Clagett's students were less generous and became convinced that Leonardo's knowledge of mediaeval sources was scanty at best. Hence even if there was a continuity Leonardo was not really part of the story.
Meanwhile, in Europe, the quest to understand the continuity of early modern science led Olschki to write his great two volume history of early technical-scientific literature.[382] This had various effects. It firmly established the concept of artist-engineers, which Gilles[383] subsequently took up. Leonardo now became one in a long line of engineers from Guido da Vigevano through Taccola, Francesco di Giorgio, pointing to the work of Agricola, Besson, Ramelli and ultimately individuals such as Leupold. The overall thrust of Olschki's work was to focus attention on technology rather than science and while confirming beyond doubt that there existed a continuity at the level of technology, it implicitly raised doubts whether something different might be the case in terms of science.
Olschki's work was used in very different ways. The marxist Zilsel[384], concerned with the sociological roots of science, cited it to support his thesis that there were three distinct strata of intellectual activity from 1300 to 1600: university scholars, humanists and artisans and that the first two strata were uninteresting. Zilsel assumed that science was synonymous with causality and that "craftsmen were the pioneers of causal thinking in the period."[385] They used quantitative methods but lacked methodical intellectual thinking:
Thus the two components of the scientific method were separated by a social barrier: logical training was reserved for upper-class scholars; experimentation, causal interest and quantitative method were left to more or less plebeian artists. Science was born when, with the progress of technology, the experimental method gradually overcame the social prejudice against manual labour and was adopted by rationally trained scholars. This was accomplished about 1600 (Gilbert, Galileo, Bacon).[386]
In Zilsel's scheme Leonardo became one of a list of craftsmen which included: Ghiberti, Piero della Francesca, Alberti, Biringuccio, Dürer, William Bourne, Robert Norman, William Borough and Palissy.[387] Having assumed the existence of a social barrier until 1600, Zilsel or his followers had no incentive to look for evidence of both strands in Leonardo a century earlier.
Nor were these ideas considered only by marxists. Drake and Drabkin[388], for instance, shared none of Zilsel's ideological assumptions, yet also argued for the importance of this practical tradition. They accepted a continuity of mediaeval mechanical ideas in the universities, but held that this was not the source of Galileo's discoveries: that Galileo owed most to a tradition of men outside the universities which went back to the time when these began publishing. This had begun with Tartaglia. It now appeared that there was a scientific revolution which began in the 1540's. The year 1543, when Tartaglia produced his vernacular edition of Euclid, was also the year that Vesalius and Copernicus published their great works. Leonardo, having been dismissed from the continuity thesis on the assumption that he was a craftsman, in spite of his 119 books, was now excluded from the craft tradition because he did not publish.
Meanwhile the work of both Duhem and Olschki had inspired interest from a very different front. The neo-Kantian philosopher Cassirer was interested in Leonardo for his own reasons. He admitted some continuity, citing Duhem concerning Leonardo's study of Cusa[389], but not Jordanus of Nemore, partly because he wished to emphasize Leonardo's break with the past, his challenge against traditionand authority and to show that, just as Cusa had developed a concept of lay piety, Leonardo established a concept of lay knowledge. Cassirer identified its key elements as a reliance on experience, proportion, measurement and ultimately mathematics. These scientific insights, he claimed, derived from his art:
The scientific theory of experience, in the version to be given it by Galileo and Kepler, will base itself on the basic concept and on the basic requirement of exactness as formulated and established by the theory of art. And both the theory of art and the theory of exact scientific knowledge run through exactly the same phases of thought.[390]
Cassirer cited Panofsky[391] who believed that he had demonstrated how Renaissance artists such as Dürer had discovered principles of descriptive geometry long before the mathematicians. In the hands of more popular writers these specific claims were translated into general notions that artists are precursors of science. De Santillana[392], for instance, used Brunelleschi as a key example. While art historians could become enthusiastic about Brunelleschi's technical skills, there was no serious evidence to link him with fundamental developments in science. This of course made nonsense of Cassirer's original claim and, more important for our purposes, meant that scholars looked to Brunelleschi[393] for things that could not be found there and once again ignored Leonardo.
One important thrust of Cassirer's claims was that Renaissance science involved more than Galileo's discovery of laws of motion, that there were basic shifts in philosophical framework involved. Cassirer himself explored these in general terms in Substance and Function.[394] This possibility excited Burtt (1924)[395] who made his own claims: that the Platonic and Pythogorean traditions involved metaphysical speculations asserting a cosmological status of mathematics which provided both a foundation and justification for science. In so doing, he drew attention to the importance of the new astronomy, and early modern science was associated with Copernicus Kepler, Galileo, Descartes, Gilbert, Boyle and Newton. He was challenged by Strong (1936) who claimed that:
The meaning of concepts employed by mathematicians and scientists in their work was found to be established in the limited operations and subject matter constituting the science. The conclusion finally driven home was the conviction that the achievements of Galileo and his predecessors were in spite of rather than because of prior and contemporary metaphysical theories of mathematics.[396]
In terms of sources, Strong focussed on mathematics from Tartaglia through Cataneo, Clavius and Veglia to Galileo. But there was more to this debate than the interpretation of specific texts. Strong was insisting that the history of science had special problems of its own which could, indeed should be, studied in isolation. This set the stage for what would later be termed an internalist approach. On the other hand, what Burtt was arguing, and what Cassirer had assumed, was that history of science was but one manifestation of a larger cultural framework. This would later become the externalist approach.[397]
The quest to understand the history of Renaissance science in a larger context led in other directions also. At Oxford, Crombie[398] set out to demonstrate that some of the key terms of philosophy necessary for experimental method which were used by Galileo and other seventeenth century thinkers already existed in the thirteenth century. As he presented the evidence it appeared as if Grosseteste had effectively articulated all the key terms of early modern science. That the actual context within which these terms were used might have changed entirely in the meantime was not discussed. Scholars such as Boas-Hall[399] were more careful, and while eager to acknowledge some continuity from the mediaeval period, insisted that there was something fundamentally different about the period 1450-1630. Although focussing on astronomy, Boas-Hall emphasized the significance of other fields such as cartography, botany, biology, medicine and mathematics.
Meanwhile, Burtt's claims about the importance of Platonism were taken up by Koyr� who became convinced that there were special connections between metaphysics and measurement.[400] He linked these concepts firmly with the Copernican revolution.[401] Gradually the Copernican revolution in astronomy could be seen as synonymous with the scientific revolution.[402] If we stop for a moment to consider these various theories, we find at least ten different claims about when the Renaissance began. Such a list is instructive because it suggests how concerns with specific kinds of problems inevitably led most scholars to overlook the possible role of Leonardo. Indeed, the only exception was Cassirer and his assumptions did not require him to make a detailed study.
| DATES | FIGURES | FIELDS | SCHOLARS |
|---|---|---|---|
| 1200-1250 | Grosseteste | Philosophy | Crombie |
| 1300-1350 | Ockham, Buridan | Philosophy, Theology | Duhem |
| 1400-1425 | Brunelleschi | Art | Santillana |
| 1450-1630 | Cusa, Leonardo | Philosophy | Cassirer |
| 1450-1630 | Cusa, Copernicus, | Astronomy | Boas-Hall |
| Brahe, Porta, Digges, | Cartography | ||
| Kepler, Galileo | Biology, Botany | ||
| 1540-1700 | Copernicus, Kepler, | Metaphysics | Burtt |
| Galileo, Descartes, | |||
| Gilbert, Boyle, Newton | |||
| 1540-1630 | Tartaglia, Cataneo, | Mathematics | Strong |
| Clavius, Galileo | |||
| Tartaglia, Guidobaldo | Mechanics | Drake | |
| Benedetti, Galileo | |||
| 1540- | Copernicus | Astronomy | Koyr�, Kuhn |
| 1600-1630 | Galileo, Gilbert | Craftsmen | Zilsel |
| Bacon | Mechanics | ||
| Surveying |
There is something else which this cursory review of historiographical trends brings to light: a gradual shift from asking questions about when and where the scientific revolution occurred to problems of how and why. Indeed, what increasingly seemed essential was no longer the discovery of a systematic approach to the universe, but rather how one systematic explanation was replaced by another, or, as Kuhn has termed it, how one paradigm replaced another.[403] Hence the assumption has spread that only changes in thought structure count: that it is really a question of a shift in mentality. The versions of these assumptions are several. In mild cases it is simply a matter of mentioning Foucault or Derrida. Others have subtle formulations about seeking to discover how the scientific mind works; that one must use new conceptual tools, above all that of the thematic content of science. So history becomes a series of case studies and quick probes. There is no longer a cumulative picture to be understood, and in this context the Renaissance and Leonardo are too early to be relevant.
There are also more radical versions which argue more strongly. Since these are universal problems, what individuals wrote on given pages of specific documents is too trivial. So one is saved the trouble of learning old languages. Indeed one can, for the most part do without texts, and can certainly spare oneself the bother of looking at manuscripts, troublesome archives and other outdated, irrelevant modes of communication. In extreme cases there is a conviction that history, if approached properly, should stop worrying about the past (which is over anyway) and concentrate instead on philosophy, which explains the logic of basic ideas; psychology which enables us to see structures of the mind and sociology which provides a social context for changes in those structures. In this extreme view history is about universal ideas, not individual opinions; about objective manifestations of truth, not subjective samples of biased creatures who do not reflect the norm. This extreme view is one that is overheard in conversation with graduate students or found expressed in their essays. If such views seem so outlandish that they are felt to have no place here, then it is sobering to recall the case of a not unknown scholar, John Hermann Randall, Jr. who, while openly admitting that he had never read the notebooks, felt that he could safely "lay down" three propositions: 1) Leonardo was not a scientist, 2) the notebooks did not contain "a single theoretical scientific idea that is essentially new or that was unknown in the organized scientific schools of his day," 3) even if Leonardo had had original ideas in scientific theory, "they remained unknown until the Paris Codici were published 1881-1891 and the Codice Atlantico in 1894."[404]