This article explores Muslim conversion to Christianity using a body of hagio-graphical sources in Arabic, Armenian, Georgian, Greek, and Latin. Through these lives of Christian martyrs, the article seeks to understand why Muslims undertook the surprising journey from “mosque to church” in the early centuries after the conquests. Many studies of Islamization are teleological, aiming to explain the large-scale conversion of the Middle East by the end of the Crusades. In contrast, this article aims to show why Islamization—especially in (...) the Umayyad and early ʿAbbāsid periods—could be highly contingent, even fragile, at a time when Muslims formed a numerical minority in many regions under their control. (shrink)

Name der Zeitschrift: Der Islam Jahrgang: 94 Heft: 1 Seiten: 5-56.

Christian Martyrs under Islam: Religious Violence and the Making of the Muslim World. By Christian C. Sahner. Princeton: Princeton University Press, 2018. Pp. xxi + 335, illus. $39.95, £34 ; $27.95, £22.

The gravitational influence of Jupiter on Saturn produces, among other things, non-negligible changes in the eccentricity of Saturn that affect the magnitude of error of Ptolemaic astronomy. The value that Ptolemy obtained for the eccentricity of Saturn is a good approximation of the real eccentricity—including the perturbation of Jupiter—that Saturn had during the time of Ptolemy's planetary observations or a bit earlier. Therefore, it seems more probable that the observations used for obtaining the eccentricity of Saturn were done near Ptolemy’s (...) time, and rather unlikely earlier than the first century AD. Even if this is not quite a demonstration that Ptolemy used observations of his own, my argument increases its probability and practically discards the idea that Ptolemy borrowed values or observations from astronomers further back than the first century AD, such as Hipparchus or the Babylonians. (shrink)

To assert that the ancient planetary theory proposed by Ptolemy was irrefutable – at least until the telescope discovery – is a bit of a cliché. The aim of this paper is to analyze in what sense it could be said that the epicycle and deferent model proposed by Ptolemy to explain the planetary movement is irrefutable and in what sense it is not. To do this, we will use the conceptual framework developed by the Structuralist Conception, and in particular, (...) the Moulines’ analysis of the “guiding principles”. DOI:10.5007/1808-1711.2010v14n2p211. (shrink)

This article analyzes the angular spacing of the degree marks on the zodiac scale of the Antikythera mechanism and demonstrates that over the entire preserved 88° of the zodiac, the marks are systematically placed too close together to be consistent with a uniform distribution over 360°. Thus, in some other part of the zodiac scale (not preserved), the degree marks have been spaced farther apart. By contrast, the day marks on the Egyptian calendar scale are spaced uniformly, apart from minor (...) errors. A solar equation of center is apparent which rises by nearly 2.7° over the preserved portion of the zodiac. The placement of the degree marks indicates that, in the preserved portion of the zodiac, the Sun was considered to run at a uniform pace of about 30° per synodic month, which is consistent with the Sun’s speed in the fast zone of the Babylonian solar theory of System A. (shrink)

In this article, I analyze the coincidence of the prediction of the Earth–Sun distance carried out by Ptolemy in his Almagest and the one he carried out, with another method, in the Planetary Hypotheses. In both cases, the values obtained for the Earth–Sun distance are very similar, so that the great majority of historians have suspected that Ptolemy altered or at least selected the data in order to obtain this agreement. In this article, I will provide a reconstruction of some (...) way in which Ptolemy could have altered or selected the data and subsequently will try to argue in favor of its historical plausibility. (shrink)

The book of Aristarchus of Samos, On the distances and sizes of the sun and moon, is one of the few pre-Ptolemaic astronomical works that have come down to us in complete or nearly complete form. The simplicity and cleverness of the basic ideas behind the calculations are often obscured in the reading of the treatise by the complexity of the calculations and reasoning. Part of the complexity could be explained by the lack of trigonometry and part by the fact (...) that Aristarchus appears unwilling to make some simplifications that could be simply taken for granted. But an important part of the complexities is due to some unnecessary inconsistencies, as recently discovered by Berggren and Sidoli (Arch Hist Exact Sci 61:213–254, 2007). In the first part of this paper, I will try to show that some of these inconsistencies are just apparent. But the complexity of the calculations and reasoning is not the only reason that could disturb a reader of the treatise. The great inaccuracy—even for the measurement methods and instruments available at those times—of one of the three input values of the treatise is really astonishing. In the sixth and last hypothesis, Aristarchus states that the moon’s apparent size is equal to 2∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{\circ }$$\end{document}, while the correct value is one-fourth of that. Some attempts have been made in order to explain such a big value, but all of them have problems. In the second part of this paper, I will propose a new speculative but plausible explanation of the origin of this value. (shrink)

To assert that the ancient planetary theory proposed by Ptolemy was irrefutable – at least until the telescope discovery – is a bit of a cliché. The aim of this paper is to analyze in what sense it could be said that the epicycle and deferent model proposed by Ptolemy to explain the planetary movement is irrefutable and in what sense it is not. To do this, we will use the conceptual framework developed by the Structuralist Conception, and in particular, (...) the Moulines’ analysis of the “guiding principles”. • DOI:10.5007/1808-1711.2010v14n2p211. (shrink)

The eighth book of Martianus Capella’s famous De Nuptiis Philologiae et Mercurii deserves a prominent place in the history of astronomy because it is the oldest source that came down to us unambiguously postulating the heliocentrism of the inner planets. Just after the paragraph in which Capella asserts that Mercury and Venus revolve around the Sun, he describes a method for calculating the size of the Moon, as well as the proportion between the size of its orbit and the size (...) of the Earth. It is possible to find some descriptions of the argument in general histories of astronomy or in books dedicated to Capella’s work, but usually they do not try to make sense of the argument. Rather, they limit themselves to describe or paraphrase what Capella says. As far as I know, there is no single study of the argument itself. The explanation for this absence is simple: the calculation offers many difficulties in its interpretation, for it shows obvious inconsistencies in the steps of the argument and apparent arbitrariness in the selection of the data used. In this article, I offer an interpretation that tries to discover, behind Capella’s confusing presentation, a well-sound argument for calculating the Moon’s absolute size. Interestingly, we have no records of this argument in other sources, at least in the form described by Capella. (shrink)

In 1975, Imre Lakatos and Elie Zahar claimed that the determination of planetary distances represents excess empirical content of Copernicus's theory over that of Ptolemy. This claim provoked an interesting discussion during the first half of the 1980s. The discussion started when Alan Chalmers affirmed that it is not correct to attribute this advantage to the Copernican system over the Ptolemaic. Other scholars criticized Chalmers's assertion, reaffirming the position of Lakatos and Zahar: one went even further, asserting that Copernicus has (...) not one but two methods for calculating distances, even though this claim was subsequently also criticized. But all participants assumed that Ptolemy has no method for calculating planetary distances. In this article, I argue that this is not correct. I argue, in fact, that Ptolemy has two independent methods for calculating the distances of some of the planets and, therefore, as far as the calculation of planetary distances is concerned, Ptolemy's system surpasses that of Copernicus. (shrink)

Tycho Brahe was not just an observer; he was a skilled theoretical astronomer, as his lunar and solar models show. Still, even if he is recognized for proposing the Geoheliocentric system, little do we know of the technical details of his planetary models, probably because he died before publishing the last two volumes of his Astronomiae Instaurandae Progymnasmata, which he planned to devote to the planets. As it happens, however, there are some extant drafts of his calculations in Dreyer’s edition (...) of Tycho’s Opera Omnia under the name Calculi ad Corrigenda Elementa orbitae Saturni, which, to the best of my knowledge, have not yet been analyzed before. In these manuscripts, Tycho starts with calculations based on the Prutenic Tables and makes a series of adjustments to the mean longitude, the longitude of the apogee, and the eccentricity to fit a series of observations of oppositions. In doing that, Tycho describes and applies a new method for obtaining accurate values for the parameters of the superior planets, he develops a divided eccentricity model of Saturn, similar to the one we know Longomontanus and Kepler applied to Mars, and finally he realizes that the true position of the Sun somehow affects the motion of Saturn around the zodiac and develops a method to correct the position of Saturn as a function of solar equation of anomaly. So, a close analysis of the calculations reveals details of the Tychonic planetary models unknown until now. The present study analyzes these drafts. (shrink)

It is well known that heliocentrism was proposed in ancient times, at least by Aristarchus of Samos. Given that ancient astronomers were perfectly capable of understanding the great advantages of heliocentrism over geocentrism—i.e., to offer a non-ad hoc explanation of the retrograde motion of the planets and to order unequivocally all the planets while even allowing one to know their relative distances—it seems difficult to explain why heliocentrism did not triumph over geocentrism or even compete significantly with it before Copernicus. (...) Usually, scholars refer to explanations of sociological character. In this paper, I offer a different explanation: that the pre-Copernican heliocentrism was essentially different from the Copernican heliocentrism, in such a way that the adduced advantages of heliocentrism can only be attributed to Copernican heliocentrism, but not to pre-Copernican heliocentrism proposals. (shrink)

This paper assumes that there is a distinction between empirical and non-empirical science. It also assumes that empirical science has two complementary parts, namely, theorization and experimentation. The paper focuses strictly on the experimental aspect of science. It is a call for reformation in African experimental science. Following a deep historical understanding of the revolution that brought about experimental philosophy this paper admits that magic was the mother, not just the “bastard sister” of empirical science. It uncovers the fact that (...) magic added the dimension of experimentation to science. This paper somewhat maintains that most of the ideas presented by some African scholars contain vestiges of the magical tradition in them. Even though this might not be a flaw by any reasonable standard, the paper still argues that there is a genuine need to separate magic from science, if we ever crave for any form of material/physical progress in Africa. I insist that the thrust of the call for paradigm shift in this paper is centered basically on experimentation. The issue of theoretical entities was introduced only to the extent such entities enhance experimental realism in the practice of African science. Of course, reformation can equally take place at the level of scientific theorization, but that is strictly beyond the scope of this paper. The fact is that those who are versed on the issues of experimentation should begin to get more focused on that aspect; and those who are given to theorization should settle with the formulation of well-structured theories. Time has indeed come for us to properly streamline our thoughts and make progress in the direction of African experimental science. In making this clarion call, we adopted a combined approach of hermeneutics and analysis. Keywords : Magic, African science, experimental science, paradigm, African thought. (shrink)

Varied theories and models of development have been advanced by many scholars to explain the failure of developmental theories and policies in Africa. This paper critically reviews the existing literature on the bane of development in Africa, arriving at what it considers as the most fundamental twin minions of underdevelopment in the continent. The two implicated interrelated issues are thought predicament and unwillingness to act. Whereas thought predicament affects the intellectual faculty, unwillingness to act is the defect of the volitional (...) and affective faculties. This paper strongly claims that without first rectifying these three core faculties of the African person, the continent can at best be chasing shadows. This, however, does not suggest that all other reasons for underdevelopment are insignificant or implausible. Well-planned educational system and deliberate conscientiousness towards enhancing the intellectual, volitional and affective faculties of humans are key to sustainable development of any state in Africa. Keywords : Thought Predicament, Unwillingness to Act, Underdevelopment, Africa. (shrink)

This essay emphasizes and explicates factors and forces that led to the creation of the Tulip futures market. It considers whether critics of that market were correct about Tulip Mania. The introductory section describes briefly the Dutch economy and states the thesis that the Dutch developed an innovative futures market. The principal section describes the forces and factors at work in the Tulip futures market. The concluding normative section assesses the bases for criticism and approves of the workings of the (...) market.Cet article met en avant et explique les facteurs et les forces qui ont conduit à la création d’un marché de futures de la Tulipe. Il examine si les analyses de ce marché étaient correctes concernant la Tulipe Mania. La section introductive décrit brièvement l’économie hollandaise et explique que les Hollandais ont développé un marché de futures innovant. La section principale décrit les forces et les facteurs qui opèrent sur le marché financier des Tulipes. La section normative de conclusion évalue les fondements des critiques et défend le fonctionnement du marché. (shrink)

In this article, we aim at presenting a thorough and comprehensive explanation of the mathematical and theoretical relation between all the aspects of Ptolemaic planetary models and their counterparts which are built according to Kepler’s first two laws. Our article also analyzes the predictive differences which arise from comparing Ptolemaic and these ideal Keplerian models, making clear distinctions between those differences which must be attributed to the structural variations between the models, and those which are due to the specific parameters (...) Ptolemy determined in the Almagest. We expect that our work will be a contribution for a better understanding not only of the Ptolemaic theories for planetary longitudes through a clearer perception of the way in which Keplerian features are present—or absent—in Ptolemy’s models, but also for a more balanced judgement of different aspects of the contribution of the first two laws of Kepler to the modern astronomical revolution. (shrink)

The eclipse predictor (or Saros dial) of the Antikythera mechanism provides a wealth of astronomical information and offers practically the only possibility for a close astronomical dating of the mechanism. We apply a series of constraints, in a sort of sieve of Eratosthenes, to sequentially eliminate possibilities for the epoch date. We find that the solar eclipse of month 13 of the Saros dial almost certainly belongs to solar Saros series 44. And the eclipse predictor would work best if the (...) full Moon of month 1 of the Saros dial corresponds to May 12, 205 BCE, with the exeligmos dial set at 0. We also examine some possibilities for the theory that underlies the eclipse times on the Saros dial and find that a Babylonian-style arithmetical scheme employing an equation of center and daily velocities would match the inscribed times of day quite well. Indeed, an arithmetic scheme for the eclipse times matches the evidence somewhat better than does a trigonometric model. (shrink)

Arab Christians and the Qurʾan from the Origins of Islam to the Medieval Period. Edited by Mark Beaumont. History of Christian-Muslim Relations, vol. 35. Leiden: Brill, 2018. Pp. xiv + 216. $120, €104.

Eric T. Poehlman, Ph.D., was an internationally recognized, tenured professor at the University of Vermont (UVM) in Burlington when, in October 2000, a junior member of Poehlman’s laboratory became convinced that he had altered data from a study on aging volunteers from the Burlington area. This suspicion developed into one of the most significant cases of scientific misconduct in the history of the US Department of Health and Human Services’ (HHS) Office of Research Integrity (ORI), launching a US Department of (...) Justice (DOJ) civil and criminal fraud investigation and, eventually, to a much publicized guilty plea and felony conviction. In the end, Dr. Poehlman admitted to 54 findings of scientific misconduct made by the UVM and ORI, agreed to retract or correct ten of his publications and to exclude himself from federal procurement and nonprocurement transactions for life. The United States Government’s handling of this case was distinguished by a highly cooperative approach that integrated the resources of the US Attorney’s Office for the District of Vermont (USAO) and both ORI and the Office of the Inspector General (OIG) in HHS in the common goal of prosecuting research fraud. (shrink)

Research in the fields of complex problem solving (CPS) and dynamic decision making using microworlds has been mainly conducted in Western industrialized countries. This study analyzes the CPS process by investigating thinking‐aloud protocols in five countries. Participants were 511 students from Brazil, Germany, India, the Philippines, and the United States who worked on two microworlds. On the basis of cultural‐psychological theories, specific cross‐national differences in CPS strategies were hypothesized. Following theories of situatedness of cognition, hypotheses about the specific frequency of (...) problem‐solving strategies in the two microworlds were developed. Results of the verbal protocols showed (a) modification of the theoretical CPS model, (b) task dependence of CPS strategies, and (c) cross‐national differences in CPS strategies. Participants’ CPS processes were particularly influenced by country‐specific problem‐solving strategies. (shrink)

Majority cycling and related social choice paradoxes are often thought to threaten the meaningfulness of democracy. But deliberation can prevent majority cycles – not by inducing unanimity, which is unrealistic, but by bringing preferences closer to single-peakedness. We present the first empirical test of this hypothesis, using data from Deliberative Polls. Comparing preferences before and after deliberation, we find increases in proximity to single-peakedness. The increases are greater for lower versus higher salience issues and for individuals who seem to have (...) deliberated more versus less effectively. They are not merely a byproduct of increased substantive agreement. Our results both refine and support the idea that deliberation, by increasing proximity to single-peakedness, provides an escape from the problem of majority cycling. (shrink)

Clandestine philosophical manuscripts, made up of forbidden works including erotic texts, political pamphlets, satires of court life, forbidden religious texts, and books about the occult, had an avid readership in the seventeenth and eighteenth centuries, becoming objects of historical research by the twentieth century. The purveyors of the clandestine could be found in the Dutch Republic, Switzerland, Denmark, Spain, and not least in Paris or London. Despite the heavy risks, including prison, the circulation of these manuscripts was a prosperous venture. (...) After Ira Wade's pioneering contribution (1938), Clandestine Philosophy is the first work in English entirely focused on the philosophical clandestine manuscripts that preceded and accompanied the birth of the Enlightenment. Topics from philosophy, political and religious thought, and moral and sexual behaviour are addressed by contemporary authors working in both America and Europe. These manuscripts shed light on the birth of pornography and provide an important avenue for investigating philosophical, religious, political, and social critique. (shrink)