Dominique Raynaud

The concept of aerial perspective has been used for the first time by Leonardo da Vinci (1452-1519). This article studies its dependence on Ptolemy’s Optica and overall on the optical tradition inaugurated by Ibn al-Haytham’s Kitāb al-Manāẓir (d. after 1040). This treatise, that was accessible through several Latin and Italian manuscripts, and was the source of many Medieval commentaries, offers a general theory of visual perception emancipated from the case of the moon illusion, in which physical and psychological factors are closely combined. Atmospheric extinction (not refraction, which it is sometimes confused with) affects the conjectured size of remote objects. This phenomenon is also the core source for a pictorial rendering of depth, that is based onto a principle different from the diminution of size.

In Scientific Controversies, Dominique Raynaud shows how organized debates in the sciences help us establish or verify our knowledge of the world. If debates focus on form, scientific controversies are akin to public debates that can be understood within the framework of theories of conflict. If they focus on content, then such controversies have to do with a specific activity and address the nature of science itself. Understanding the major focus of a scientific controversy is a first step toward understanding these debates and assessing their merits. Controversies of unique socio-historic context, disciplines, and characteristics are examined: Pasteur’s germ theory and Pouchet’s theory of spontaneous generation; vitalism advocated at Montpellier versus experimental medicine in Paris; the science of optics about the propagation of visual rays; the origins of relativism (the Duhem-Quine problem). Touching on the work of Boudon, Popper, and others, Raynaud puts forward an incrementalist theory about the advancement of science through scientific controversies. The debates Raynaud has selected share in common their pivotal importance to the history of the sciences. By understanding the role of controversy, we better understand the functioning of science and the stakes of the contemporary scientific debates.

Brisant l’image idéale de la science consensuelle, les controverses scientifiques sont aujourd’hui devenues un sujet privilégié de la sociologie et de l’histoire des sciences. Elles sont par ailleurs impliquées au cœur des débats sur les méthodes des sciences sociales. Si l’analyse des controverses scientifiques doit beaucoup aux approches inaugurées par les courants relativistes et constructivistes des années 1970-1980, ce livre montre que les études contemporaines ont tout à gagner à réintroduire ce qui a été le principal tabou des trente dernières années: la vérité. Cette conclusion n’est pas le résultat d’une méditation abstraite sur le destin de la sociologie et de l’histoire des sciences. C’est le résultat d’études de cas, portant sur des disciplines telles que la biologie (la thèse des générations spontanées, débattue entre Pasteur et Pouchet), de la médecine (le vitalisme opposé à la médecine expérimentale naissante), de la stéréotomie (les « Guerres perspectives » qui ont agité le Paris des années 1640), de la perspective (la mathématisation de la perspective dans l’Italie du 16e siècle) ou de l’optique (la question de l’intromission, discutée à Oxford). De querelles médiévales à des disputes plus récentes, ces études suivent un même fil conducteur : interroger les rôles de la rationalité, des conventions et des croyances collectives dans la construction des théories scientifiques. L’auteur défend une théorie incrémentaliste du progrès scientifique: pour autant qu’il suive des règles, le débat est un moyen pratique de tester la robustesse d’une théorie et de départager les théories rivales. Le fait que les débats soient souvent marqués par la passion et les émotions est sans intérêt ; l’important est que ces échanges réglés puissent, par la production d’arguments publics, s’approcher de la vérité. C’est une façon de répondre à la question : Pourquoi l’activité scientifique est-elle conflictuelle?

Contemporary sociology of scientific knowledge (SSK) is defined by its relativist trend. Its programme often calls for the support of philosophers, such as Duhem, Quine, and Wittgenstein. A critical re-reading of key texts shows that the main principles of relativism are only derivable with difficulty. The thesis of the underdetermination of theory doesn't forbid that Duhem, in many places, validates a correspondence-consistency theory of truth. He never said that social beliefs and interests fill the lack of underdetermination. Quine's idea of a selective revision of hypotheses, as well as the neat incompatibility between holism and conventionalism, openly challenges the principles of relativism. Wittgenstein's work, which is not presented in book-form but rather as a tree, forces us to avoid aphoristic choices that credit any text-excising. This remark allows us to tackle the passages that sociological relativism is based on.Mathematical conventions are not anthropological objects. When Wittgenstein examines the "language-games," he only speaks of the functioning of natural language, not to be confused with scientific formal languages. We then should render the formula "language-game" by "well-defined, explicit and compulsory rules of communication", which is a much less attractive formula for relativism. Consequently, there does not exist a real continuity between the epistemologies of Duhem, Quine and Wittgenstein, and the recent works of the SSK.

The controversy between the medical schools of Paris and Montpellier extends roughly from the death of Barthez (1806) to the publication of the Introduction to the study of experimental medicine of Claude Bernard (1865), with a peak during which the controversy merges with the polemic between Louis Peisse and Jacques Lordat (1840-1843). This study aims to document as accurately as possible the arguments that were exchanged during this controversy, by seeking their reasons and explaining how the experimental medicine in Paris ultimately took the lead over the vitalism championed by the school of medicine in Montpellier.

The modern physiological optics introduces the notions related to the conditions of fusion of binocular images by the concept of correspondence, due to Christiaan Huygens, and by an experiment attributed to Christoph Scheiner. The conceptualization of this experiment dates, in fact, back to Ptolemy and Ibn al-Haytham. The present paper surveys Ibn al-Haytham's knowledge about the mechanisms of binocular vision. The article subsequently explains why Ibn al-Haytham, a mathematician, but here an experimenter, did not give the circular figure of the theoretical horopter, construction due to Gerhard Vieth and Johannes Müller. But, on the other hand, it is clear that Ibn al-Haytham's experimental study puts in place the notion of corresponding points, the cases of homonymous and cross diplopia, and even prepares the discovery of Panum area.

L'essor de la perspective linéaire a suscité de nombreuses polémiques tout au long du Quattrocento et du Cinquecento, opposant les partisans d'une géométrisation artificialiste de la vision à ceux qui vantaient les qualités du dessin d'après nature ou invoquaient des arguments de nature physiologique. Ces débats peuvent être retracés à partir des quatre alternatives qui en constituent le noyau dur : champ de vision restreint vs. large ; immobilité vs. mobilité oculaire ; tableau plan vs. curviligne ; vision monoculaire vs. binoculaire. En retenant les premiers termes de ces quatre alternatives, l'histoire de la perspective a rejeté de nombreux systèmes hétérodoxes. Du point de vue de la mathématisation, l'intérêt de ces débats tient à ce qu'ils ont succédé, et non précédé, l'adoption du dispositif perspectif comme intersection de la pyramide visuelle. L'histoire de la perspective linéaire offre ainsi un authentique cas de justification a posteriori des fondements ou, pour ainsi dire, de mathématisation à rebours

Le regain actuel de la sociologie de l'art semble lié à un essai de constitution d'un programme de 'sociologie des œuvres', différencié de la classique sociologie de la production et de la réception artistiques. Ce programme, épigone des théories de la communication, fait l'hypothèse de codes iconiques et plastiques. L'étude des interprétations des rayures de D. Buren et de la pyramide du Grand Louvre de I. M. Pei invalide l'existence de tels codes. La grande variabilité des interprétations est alors expliquée dans le cadre du modèle inférentiel avancé par Sperber et Wilson (1989). L'absence de code et le caractère auto-réfutant de certaines propositions met en doute les chances de succès de ce programme de recherche

This volume has 41 chapters written to honor the 100th birthday of Mario Bunge. It celebrates the work of this influential Argentine/Canadian physicist and philosopher. Contributions show the value of Bunge’s science-informed philosophy and his systematic approach to philosophical problems. The chapters explore the exceptionally wide spectrum of Bunge’s contributions to: metaphysics, methodology and philosophy of science, philosophy of mathematics, philosophy of physics, philosophy of psychology, philosophy of social science, philosophy of biology, philosophy of technology, moral philosophy, social and political philosophy, medical philosophy, and education. The contributors include scholars from 16 countries. Bunge combines ontological realism with epistemological fallibilism. He believes that science provides the best and most warranted knowledge of the natural and social world, and that such knowledge is the only sound basis for moral decision making and social and political reform. Bunge argues for the unity of knowledge. In his eyes, science and philosophy constitute a fruitful and necessary partnership. Readers will discover the wisdom of this approach and will gain insight into the utility of cross-disciplinary scholarship. This anthology will appeal to researchers, students, and teachers in philosophy of science, social science, and liberal education programmes. 1. Introduction Section I. An Academic Vocation Section II. Philosophy Section III. Physics and Philosophy of Physics Section IV. Cognitive Science and Philosophy of Mind Section V. Sociology and Social Theory Section VI. Ethics and Political Philosophy Section VII. Biology and Philosophy of Biology Section VIII. Mathematics Section IX. Education Section X. Varia Section XI. Bibliography.

The perfect compass, used by al-Qūhī, al-Sijzī and his successors for the continuous drawing of conic sections, reappeared after a long eclipse in the works of Renaissance mathematicians like Francesco Barozzi in Venice. The resurgence of this instrument seems to have depended on its interest to solve new optico-perspective problems. Having reviewed the various instruments designed for the drawing of conic sections, the article is focused on the sole conic compass. Theoretical and empirical applications are detailed. Contrarily to the common thesis of an independant discovery, various elements suggest a direct descent between the birkār al-tāmm of the Arabic mathematical tradition and the Italian conic compass. Then we present the most probable transmission hypothesis involving: 1° Ibn Yūnus and his disciples of Mosul, 2° Sultan Malik al-Kāmil in Damas, 3° Master Theodore and Frederick II at the court of Sicily, 4° Andalò di Negro and Robert of Anjou in Naples, 5° Lorenzo della Volpaia, Vinci, Sangallo and Michelangelo in Florence, 6° Ausonio, Contarini, Thiene and Francesco Barozzi in Venice.

This article studies a fragment on the conic sections that appear in the Codex Atlanticus, fols. 611rb/915ra. Arguments are put forward to assemble these two folios. Their comparison with the Latin texts available before 1500 shows that they derive from the De speculis comburentibus of Alhacen and the De speculis comburentibus of Regiomontanus, joined together in his autograph manuscript. Having identified the sources, and discussed their mathematics, the issue of their transmission is targeted. It is shown that these notes were written by Paolo dal Pozzo Toscanelli, through whom they reached the notebooks of Leonardo da Vinci.

Why did linear perspective rise in trecento–quattrocento central Italy rather than in any other cultural context? This book provides new insight into the question of the early Italian pioneership in perspective, building on the fact that many references to optics can be found in Renaissance treatises. The fact that most of the medieval optical manuscripts were written by Franciscan masters—the best known among them being Roger Bacon and John Pecham—suggests the need for a closer look at how the medieval universities (studia generalia) operated. An in-depth study of recruitment highlights the exceptional mobility of masters and lectors throughout Europe. However, through the thirteenth and fourteenth centuries, the closer a university was to central Italy, the more cosmopolitan it was. This is a result of the topology of the academic network, since cosmopolitanism depends on the studium’s closeness centrality. This is why, through the masters’ mobility, knowledge circulating in the network preferentially flowed into central Italy.

In view of the progress made in recent decades in the fields of stemmatology and the analysis of geometric diagrams, the present article explores the possibility of establishing the stemma codicum of a handwritten tradition from geometric diagrams alone. This exploratory method is tested on Ibn al-Haytham’s Epistle on the Shape of the Eclipse, because this work has not yet been issued in a critical edition. Separate stemmata were constructed on the basis of the diagrams and the text, and a comparison showed no major differences. The greater reliability of a stemma codicum constructed on the basis of the diagrams rather than the text of a mathematical work is discussed and preliminary conclusions are drawn

Ce livre est un livre d’épistémologie de la sociologie. L’objectif est d’appliquer des méthodes analytiques pour clarifier le vocabulaire, expliciter des relations non-apparentes entre concepts, dégager la portée d’une méthode, ou souligner les incohérences d’un programme de recherche. Les questions épineuses ne sont pas écartéees: Comment clarifier des notions confuses? Peut-on mathématiser les concepts sociologiques? Peut-on pratiquer la sociologie comme on pratique les sciences naturelles? Quelle est la place du déterminisme? Chaque question est examinée à la fois dans sa structure logique et sur des cas concrets. La mathématisation est étudiée sur les mécanismes agrégatifs et sur les modèles de diffusion des innovations. La sociologie expérimentale – généralement méconnue dans la sociologie française – est étudiée sur des programmes de relogement, la diffusion de l’information, ou la genèse de la solidarité sociale. Le livre aborde frontalement la question du déterminisme, du naturalisme, du matérialisme et du scientisme, réputés intenables en sociologie. L’enquête montre que leur rejet résulte généralement de confusions conceptuelles. Une fois écartées, peu d’obstacles s’opposent à leur emploi en sociologie. L’objet de ce livre est la sociologie fondamentale: ensemble des mécanismes qui structurent la production des connaissances sociologiques de base à partir de concepts, programmes ou principes, c’est-à-dire tout ce qui ne relève pas de l’expérience immédiate du terrain et des mondes sociaux.

This article aims to test a new method of dating optico-astronomical manuscripts, using Ibn al-Haytham’s Epistle on the Shape of the Eclipse as the test case. This work is selected because of indications that its diagrams are based on reality. After clarifying the observation conditions, an astronomical ephemeris is applied to sift through the eclipses that occurred during Ibn al-Haytham’s life throughout the area he is believed to have sojourned. Next, the remaining eclipses are sorted by computing the image projection. The results show that Ibn al-Haytham’s Epistle is likely to have reported the partial solar eclipse of 28 Rajab A.H. 380/21 October 990 in Baṣra. Because this exercise is primarily the test of a new method, this finding should be regarded as a tentative outcome, pending further information.

The modern physiological optics introduces the notions related to the conditions of fusion of bi- nocular images by the concept of correspondence, due to Christiaan Huygens (1704), and by an experiment attri- buted to Christoph Scheiner (1619). The conceptualization of this experiment dates, in fact, back to Ptolemy (90- 168) and Ibn al-Haytham (d. af. 1040). The present paper surveys Ibn al-Haytham's knowledge about the mecha- nisms of binocular vision. The article subsequently explains why Ibn al-Haytham, a mathematician, but here an experimenter, did not give the circular figure of the theoretical horopter, construction due to Gerhard Vieth (1818) and Johannes Müller (1826). But, on the other hand, it is clear that Ibn al-Haytham's experimental study puts in place the notion of corresponding points, the cases of homonymous and cross diplopia, and even prepares the discovery of Panum area. L'optique physiologique moderne introduit les notions relatives aux conditions de fusion des images binoculaires par le concept de correspondance, prêté à Christiaan Huygens (1704), et par une expérience attribuée à Christoph Scheiner (1619). L'article montre que la conceptualisation de l'expérience remonte en fait à Ptolémée (90-168) et à Ibn al-Haytham (m. ap. 1040), et précise les connaissances que ce dernier avait des mécanismes de la vision binoculaire. Il est ensuite expliqué pourquoi Ibn al-Haytham, mathématicien mais ici expérimentateur, ne donne pas la forme circulaire de l'horoptère théorique, dont la construction revient à Gerhard Vieth (1818) et Johannes Müller (1826). En revanche, l'étude expérimentale d'Ibn al-Haytham met en place la notion de points correspondants, les cas de diplopie homonyme et croisée et prépare même la découverte de l'aire fusionnelle de Panum

This paper wonders why the Franciscan order took part in the diffusion of optics more than other medieval organisation, both religious and secular. First, clues of this social asymmetry are given. Then, an explanation is put forward: 1. An initial asymmetry existed, by the fact that Grosseteste’s optics was known in the Franciscan studium of Oxford; 2. Since that date, optics spread among the order by a network effect; 3. The rivaltry between the mendicant orders and the homophilia that presided over their conventual libraries’ purchasing policy finally explains why other contemporary organizations, similarly structured, took a smaller interest into optics. In spite of an evident topical connection, this explanation deeply differs from the analysis that has been applied to the Puritans’ and Jesuits’ scientific activity in XVIIth and XVIIIth centuries classical Europe. It does not appeal to the heavy hypothesis of ethos in order to understand scientific development.

In this article, we publish the critical edition of Andalò di Negro’s De compositione astrolabii, with English translation and commentary. The mathematician and astronomer Andalò di Negro presumably redacted this treatise on the astrolabe in the 1330s, while residing at the court of King Robert of Naples. The present edition has three purposes: first, to make available a text missing from the previous compilations of works by Andalò di Negro; second, to revise a privately circulated edition of the text; and third, to help disseminating one of the rare Latin texts presenting the principles of the stereographic projection which underlie the construction of the astrolabe.

In the Quattrocento and Cinquecento the rise of linear perspective caused many polemics which opposed the supporters of an artificial geometrisation of sight to those who were praising the qualities of the drawing according to nature, or were invoking some arguments on a physiological basis. These debates can be grouped according to the four alternatives that form their central concerns: restricted vs. broad field of vision; ocular immobility vs. mobility; curvilinear vs. planar picture; monocular vs. binocular vision. By retaining the first terms of these four alternatives, the history of perspective eliminated many heterodox constructions. From the viewpoint of mathematisation the interest of these debates is that they succeeded, rather than preceded, the adoption of a perspective system defined by the intersection of the visual pyramid. Thus the history of linear perspective constitutes a genuine case of a posteriori justification, or, put differently, it gives us a case of upside down mathematisation.

“La obra que usted está examinando es el primer estudio de todas las facetas de la tecnología, desde la concepción del artefacto hasta los problemas filosóficos y jurídicos que suscitan el saber y el hacer tecnológicos… Además, Raynaud califica de tóxica para la propia tecnología a la política utilitarista de dar prioridad al ‘desarrollo’ por sobre la investigación básica, ya que todas las innovaciones tecnológicas han utilizado conocimientos básicos… El utilitarismo que pregonan los economistas neoclásicos y los estadistas miopes es el peor peligro que enfrenta la tecnología, la que languidece sin el apoyo de las ciencias básicas. Como decía Guido Beck, mi maestro de física, no han entendido que no puede haber leche de vaca sin vaca”. – Mario Bunge

Leonardo’s research on the eye and vision has given rise to contrasting assessments, ranging from the apology of his explanation of how the eye works as a camera obscura to the most critical attitude. The negative judgments derive some of their strength from the fact that the practice of anatomy and linear perspective are well documented in Leonardo. Thus one expects him to have had empirically based knowledge of the organs dissected, as well as comprehensive skills in optics. As we will see, none of these ideas is entirely right.

In Résolution des quatre principaux problèmes d’architecture (1673) then in Cours d’architecture (1683), the architect–mathematician Nicolas-François Blondel addresses one of the most famous architectural problems of all times, that of the reduction in columns (entasis). The interest of the text lies in the variety of subjects that are linked to this issue. (1) The text is a response to the challenge launched by Curabelle in 1664 under the name Étrenne à tous les architectes; (2) Blondel mathematicizes the problem in the “style of the Ancients”; (3) The problem is reformulated and solved through the continuous drawing of the curve; (4) Blondel refutes the uniqueness of the curve by enumerating a variety of solutions (conchoid, spiral, parabola, ellipse, circle, hyperbola). This exuberance responds to an intention that does not coincide with the state of the art of mathematics at the end of the seventeenth century, nor with the taste for geometry of the Ancients, nor with any pedagogical project. This feature is explained by Blondel’s plan to found architecture on scientific bases. The reasons for his failure are analysed.

Despite the enthusiasm generated by social constructionism in the study of scientific debates, this contribution shows that – down to their praxeological dimension – the study of scientific controversies can benefit from sources ignored in today sociological literature. The contribution discloses these sources from the works of Shams al-Dīn al-Samarqandī (ca. 1250–ca. 1302), who is the first author to have offered etiquettes of investigation and debate (ādāb al-baḥth wa-al-munāẓara). Consequences are drawn towards constructivist epistemology.

This book explores the interrelationships between optics, vision and perspective before the Classical Age, examining binocularity in particular. The author shows how binocular vision was one of the key juncture points between the three concepts and readers will see how important it is to understand the approach that scholars once took. In the Middle Ages and the Renaissance, the concept of Perspectiva – the Latin word for optics – encompassed many areas of enquiry that had been viewed since antiquity as interconnected, but which a erwards were separated: optics was incorporated into the field of physics (i.e., physical and geometrical optics), vision came to be regarded as the sum of various psycho-physiological mechanisms involved in the way the eye operates (i.e., physiological optics and psychology of vision) and the word ‘perspective’ was reserved for the mathematical representation of the external world (i.e., linear perspective). The author shows how this division, which emerged as a result of the spread of the sciences in classical Europe, turns out to be an anachronism if we confront certain facts from the immediately preceding periods. It is essential to take into account the way medieval scholars posed the problem – which included all facets of the Latin word perspectiva – when exploring the events of this period.

650 pp. – This book is a continuation of the research on the representation of the eye initiated by Prof. Ludwig Choulant (University of Dresden) and Prof. Hugo Magnus (University of Breslau) at the end of the 19th and beginning of the 20th century. The aim of the book is to provide all those who need information on how the eye was conceived in a given historical context, with clear and concise iconographic and lexicographic data. The first section contains about 700 images of the eye (first handwritten, then printed) distributed among 450 authors. Each record reproduces the figures of the eye with their own specific anatomical terminology. The second section provides a cluster analysis of the eye figures: the result is a dendrogram, which accounts for the main types of representation of the eye found in the history of ocular anatomy. The work is complemented by a 40-page Index of Concepts containing all the anatomical terms found in the book.

Unlike the physical sciences, sociology is frequently described as an interpretative non-experimental science. Comparative epistemology sheds new light on this claim. 1. Experimentation is not a constant character of the physical sciences; 2. Experimental hypothetical-deductive reasoning, including the test of predictions, is also practicable in sociology. The argument is developed by a detailed step-wise comparison of the prediction of light ray deviation within the Sun’s gravitational field made in 1919 (physics) and the prediction of 8% cosmopolitanism of Cambridge University between 1250 and 1350 (sociology). Extensive analysis of regent masters’ prosopographic notes yields the result of 9.5 percent cosmopolitanism, which is close to the theoretical prediction. Au contraire des sciences physiques, la sociologie est souvent décrite comme une science interprétative et non-expérimentale. L’épistémologie apporte un éclairage nouveau sur cette position : 1) L’expérimentation n’est pas un trait constant des sciences physiques ; 2) Le raisonnement expérimental est également applicable en sociologie. L’argument est développé en comparant en détail le test de la prédiction d’une déviation des rayons lumineux dans un champ de gravitation effectué en 1919 et le test de la prédiction d’un taux de cosmopolitisme de 8 % de l’université de Cambridge dans la période 1250-1350. Le dépouillement des notices prosopographiques des maîtres régents donne un résultat de 9,5 % proche de la prédiction théorique initiale.

This article is a study of geometric constructions. We consider, as an illustration, the methods used for dividing the straight line into n equal parts (n-section). Architects and practicioners of classical Europe had at their disposal a broad range of geometric constructions: ancient ones were edited and translated, whereas new solutions were constantly published. The wide variety and reasons for selection of these geometric constructions are puzzling: the most widespread construction was not the simplest one. This article wonders why so many constructions were used to solve the same problem and why tedious methods were used. It is argued that the practical conditions and scale at which the problem was tackled could account for such diversity.