David C. Lindberg

Reappraisals of the scientific revolution

List of contributors Acknowledgments Introduction Robert S. Westman and David C. Lindberg 1. Conceptions of the scientific revolution from Bacon to Butterfield: a preliminary sketch David C. Lindberg 2. Conceptions of science in the scientific revolution Ernan McMullin 3. Metaphysics and the new science Gary Hatfield 4. Proof, portics, and patronage: Copernicuss preface to De revolutionibus Robert S. Westman 5. A reappraisal of the role of the universities in the scientific revolution John Gascoigne 6. Natural magic, hermetism, and occultism in early modern science Brian P. Copenhaver 7. Natural history and the emblematic world view William B. Ashworth, Jr. 8. From the secrets of nature to public knowledge William Eamon 9. Chemistry in the scientific revolution: problems of language and communication Jan V. Golinski 10. The new philosophy and medicine in seventeenth-century England Harold J. Cook 11. Science and heterodoxy: an early modern problem reconsidered Michael Hunter 12. Infinitesimals and transcendent relations: the mathematics of motion in the late seventeenth century Michael S. Mahoney 13. The case of mechanics: one revolution or many? Alan Gabbey Index.

Alhazen's Theory of Vision and Its Reception in the West

HE MOST SERIOUS problem facing the Muslim heirs of Greek thought was the extraordinary diversity of their inheritance. Among theories of optics, for instance, Muslim thinkers had the following choice: the emission theory of sight of Euclid and Ptolemy, which postulated visual rays emanating from the observers eye; the older Epicurean intromission theory, which reversed the rays and made them corporeal; the combined emission-intromission theories of Plato and Galen; and some enigmatic statements of Aristotle about light as qualitative change in a medium.1 These Greek theories generated a wide assortment of optical theories in Islam, two of which came to dominate. Hunain ibn Ishaq (d. 877), the most prolific translator of scientific works into Arabic, argued for a combined emission-intromission theory in the tradition of Plato and Galen.2 Al-Kindi (d. c. 873) agreed with Hunain that rays are emitted by both the visible object and the eye, although he couched his theory in terms of a general emanation of power having Stoic and Neoplatonic origins and appropriated the geometrical approach to optics appearing in the works of Euclid and Ptolemy.3 Avicenna (Ibn Sina, d. 1037) took exception to the views of Hunain and al-Kindi, denying that visual rays are of any use in explaining the process of sight and insisting on a complete intromission theory.4 These and other Muslim philosophers made important

The theory of Pinhole images in the fourteenth century

Toward the end of the thirteenth century, pinhole images were elevated to the status of un probleme celebre by the work of Roger Bacon, Witelo, and John Pecham. Earlier authors had commented on the remarkable ability of noncircular apertures to produce circular images of the sun, but little had been made of the fact. Bacon, however, wrote a sizable treatise on burning mirrors, one fourth of which he devoted to pinhole images and their implications for theories of the propagation of light. Witelo considered the problem of pinhole images in six propositions of his Perspectiva. Pecham devoted the longest proposition of his Perspectiva communis and sections of his Tractatus de perspectiva and De sphera to the same problem.1 The theory of pinhole images continued to occupy a position of considerable importance in the fourteenth century. The two most significant optical treatises of the century, the Questiones super perspectivam by Henry of Langenstein and the work of the same title by Blasius of Parma, each devote a full question to pinhole images. Earlier in the century, Egidius of Baisiu and Levi ben Gerson also dealt with the problem.2 The problem of pinhole images attracted so much attention in the thirteenth century because it posed a fundamental optical problem. At least since Euclid, the principle of rectilinear propagation of light had served as the foundation for an elaborate superstructure of geometrical optics. Although physical, physiological, and even psychological matters frequently intrude, a glance at almost any optical treatise written before the fourteenth century3 immediately reveals that geometrical elements predominate. Yet the phenomena of pinhole images seemed to cast doubt on the rectilinear propagation of light and thereby on the entire optical

Beyond War and Peace: A Reappraisal of the Encounter between Christianity and Science

On a December evening in 1869, with memories of civil war still fresh in their minds, a large audience gathered in the great hall of Cooper Union in New York City to hear about another conflict, still taking its toll—“with battles fiercer, with sieges more persistent, with strategy more vigorous than in any of the comparatively petty warfares of Alexander, or Caesar, or Napoleon.” Although waged with pens rather than swords, and for minds rather than empires, this war, too had destroyed lives and reputations. The combatants? Science and Religion.

On the Applicability of Mathematics to Nature: Roger Bacon and his Predecessors

Roger Bacon has often been victimized by his friends, who have exaggerated and distorted his place in the history of mathematics. He has too often been viewed as the first, or one of the first, to grasp the possibilities and promote the cause of modern mathematical physics. Even those who have noticed that Bacon was more given to the praise than to the practice of mathematics have seen in his programmatic statements an anticipation of seventeenth-century achievements. But if we judge Bacon by twentieth-century criteria and pronounce him an anticipator of modern science, we will fail totally to understand his true contributions; for Bacon was not looking to the future, but responding to the past; he was grappling with ancient traditions and attempting to apply the truth thus gained to the needs of thirteenth-century Christendom. If we wish to understand Bacon, therefore, we must take a backward, rather than a forward, look; we must view him in relation to his predecessors and contemporaries rather than his successors; we must consider not his influence, but his sources and the use to which he put them.

Lines of Influence in Thirteenth-Century Optics: Bacon, Witelo, and Pecham

HISTORIANS of mediaeval optics have devoted a large measure of their effort to the work of three men who wrote on optics in the second half of the thirteenth centuryRoger Bacon, Witelo, and John Pecham. Such an emphasis is not without justification: not only were they the ones who, under the influence of Alhazens Perspectiva, produced the great thirteenth-century synthesis of optical knowledge, but it was chiefly through the dissemination of their works in manuscripts and printed editions that this optical knowledge was transmitted to subsequent generations. Because Bacon, Witelo, and Pecham all composed their optical works within a period of two decades or less (a relatively short period of time by mediaeval standards of communication), the question of influence is unavoidably raised. Not only is this question pertinent to the history of mediaeval optics, but the alleged influence of o-ne upon another has been used as a basis for generalizations regarding the course of thirteenth-century science in general;1 it is therefore of considerable importance to examine all the available evidence and decide who really influenced whom. To many historians, it has appeared that the lines of influence linking Bacon, Witelo, and Pecham can be easily determined from elementary considerations. Since it has been generally agreed that Bacon wrote his principal optical works before Witelo and Pecham wrote theirs, it has seemed self-evident that Witelo and Pecham read and were influenced by Bacons works. To complete the picture, Witelo is explicitly cited in printed editions of Pechams Perspectiva communis.2 But unfortunately, the problem of influence cannot be so easily resolved. In the first place, Bacons works on optics were composed in partial secrecy and forwarded to the Papal court with little immediate circulation, and it cannot be assumed, without a comparison of doctrines and a study of the mechanics of transmission, that they were read by anybody. Secondly, the citations to Witelo appearing in printed versions of Pechams Perspectiva communis are spurious, having been inserted into the 1542 (Nuremberg) edition by its editor, Georg Hartmann, and reprinted in subsequent editions.3 It is thus apparent that the question of influence must be reopened.

Roger Bacon's Theory of the Rainbow: Progress or Regress?

HE PRIMARY RAINBOW is explained by Theodoric of Freiberg (d. c. 1311) in the following way: when sunlight falls on individual drops of moisture the rays undergo two refractions (upon ingress and egress) and one reflection (at the back side of the drop) before transmission to the eye of the observer.1 The path of sunlight within the drop, as correctly traced by Theodoric, is illustrated in Figure 1. Yet, before the rainbow

Science and the Early Christian Church

The discipline of history of science continues to expand. The need becomes obvious for synthetic articles that will review the specialist literature of a given field or problem area and report on expert opinion, to keep us abreast of the growing flood of work remote from our own specialties. Fortunately, this need is matched by new opportunities made possible by the ongoing Fund Drive of the History of Science Society. We are now in a period of transition, in which we hope to see a revived Osiris stand alongside a newly invigorated Isis. That new Isis will seek from time to time to offer the review articles and synthetic essays which we all need. The following essay may serve as a precursor of this new Isis genre. There is no field of more obvious relevance-not only to those of us who teach, but to all of us as citizens and intellectuals-than that of science and religion. Ones understanding of this larger subject depends directly on ones perceptions about science and the early church. Isis is therefore pleased to present, by way of experiment, David Lindbergs authoritative discussion. -A.T.

The Cause of Refraction in Medieval Optics

Attempts in antiquity and the Middle Ages to determine the mathematical law of refraction are well known. In view of the movement toward the mathematization of physical laws, which has made great gains since the beginning of the seventeenth century, and of the efforts of Hariot, Kepler, Snell, and Descartes to determine the true mathematical ratio between the angles of incidence and refraction, it is understandable that historians of pre-seventeenth-century science should concentrate on the quantitative aspects of refraction. But to do so is to gain a distorted picture of early optical thought, for as much effort was actually devoted to understanding the cause of refraction as to finding the mathematical law of refraction.

Kepler and the Incorporeality of Light

It is my purpose in this paper to explore Johannes Kepler’s ideas about the nature of light. It is my premise that we can succeed in this venture only if we go to the trouble of viewing Kepler’s theory against the background of the ancient and medieval optical tradition, which formed its immediate historical context. One reason for past failures is that we have inspected Kepler from the perspective of Newton or the present, rather than that of Aristotle or Plotinus or Roger Bacon. We have been so impressed with Kepler’s optical successes, in devising a new theory of vision, solving the ancient problem of the camera obscura, and formulating a geometrical theory of the telescope, that we have expended little effort in discovering whence they came or what they meant in the context of the optical tradition. Yet surely it was by grappling with the past — attempting to come to terms with the ideas of his predecessors, to separate the gold from the dross in ancient and medieval optical theory, to introduce clarity and precision, and to adjust existing theory to the teachings of sense, intellect, and philosophical presupposition — that Kepler fashioned his own theory. In short, Kepler’s achievement can be fully appreciated only if viewed within a disciplinary tradition. This will not strike historians as a novel thesis; the novelty will come if we put it into practice.