Yael Kedar

The idea that nature is governed by laws is credited to the natural philosophers of the scientific revolution. Early modern science embraced the category of "law" in order to render natural regularities intelligible. In this influential and most productive conception, nature submits to governing laws which are imposed from without. Our inquiry focuses on the period before this view of nature coalesced. In our collection of essays we ask by which principles and concepts natural regularities were accounted for in pre-1700 thought. Since it has often been the case that natural regularities were not discussed per se, we expand the range of our investigation to the way natural order was conceived at large.

Many historians of science consider laws of nature a modern category. Some, however, claim for the consolidation of a nomic conception of nature in the thirteenth and fourteenth centuries. The first time that specific laws were formulated in medieval texts was in the scientific works of Robert Grosseteste (c.1175–1253), who stated the law of refraction and the law of reflection of light rays, and of Roger Bacon (c. 1220–1292/1293), who added the law of the gravity of water and the law of universal nature. It is probable that Bacon’s concept of optical law had reached the modern times before Descartes. The nominalists-voluntarists of the fourteenth century, and most prominently William of Ockham (1288– c.1348), may have had an important part in the emergence of the concept of laws too. They rejected the realism of forms and immanent factors and stressed the sovereignty of God in creating and the contingency of his imposed decrees. This philosophy of nature provided a context within which the idea of a law of nature was comprehensible and natural. It had reached seventeenth-century scientists through Martin Luther (1483–1546).

Roger Bacon was born in Ilchester in either 1214 or 1220. After his matriculation at Oxford, he was one of the pioneers to teach Aristotle at the University of Paris. His return to Oxford in the late 1240s marked a turning point in his career. He joined the Franciscans in 1257, and in 1267/1268, he sent three works, comprising a plan for the reorganization of Christian studies, to the Pope. In his Parisian phase of career, he developed the idea of the utmost significance of the speaker’s intention and original theories of imposition and equivocation. He affirmed that universals are extramental, believed in innate confused knowledge, and held to the theory of universal hylomorphism. In his mature phase of thought, he proposed an order of sciences in which the practical sciences received precedence, advocated the use of experimental method, developed the theory of the multiplication of species, and combined it with Alhacen’s ideas on light and vision. By this move, he initiated the tradition of the science of Perspectiva in the West. Bacon viewed nature as a coherent system governed by laws and formulated some of them. He stressed the importance of mathematics in providing scientific explanations and drew geometrical diagrams exemplifying various optical phenomena. Bacon described the details of the workings of the sensitive soul and ascribed complex cognitive capacities to animals. He presented an original classification of signs and reversed the linguistic triangle prescribed by Aristotle and Boethius. His view of matter as positive and worthy of investigation found expression in his strong notion of representation, advocating the need to portray both formal and material aspects in cognitive contents and language.

Medieval Latin optics had its sources in Greek and Arab thinkers, including Aristotle, Euclid, Ptolemy, Galen, al-Kindi, Avicenna, and Alhacen. Its prominent scholars had been Robert Grosseteste, Albert the Great, Roger Bacon, John Pecham, Witelo, and Theodoric of Freiburg. The medieval Latins discussed light’s ontological status and whether its mode of existence in the medium is spiritual or material. They adopted from Alhacen the model of radiation from individual point-sources and the idea of spherical propagation, thereby opening their account to radial analysis. Grosseteste identified light with the first corporeal form, which inserts dimensions onto matter, and Bacon developed the theory of multiplication of species, of which the activity of light was the observable instance. Light thus became the key to the workings of natural causality. The perspectivists formulated optical laws and applied them in explanations of natural phenomena such as the rainbow, pinhole images, and in their account of sight. They debated about the direction of the visual cone and subjected the eye to geometrical analysis. They explained sight as caused by the perpendicular species, since they are the shortest and therefore the strongest. Upon entering the eye, perpendicular rays pass through the cornea, refract at the rear surface of the crystalline lens, and project through the opening of the optic nerve. Sight perceives light and color directly, and twenty more visual qualities through complex processes of comparison, concept-formation, and reasoning. Attention was given to the various faculties of the brain – such as imagination and memory – and their role in processing visual information.

I claim that Grosseteste and Bacon played a crucial role in the evolution of the idea that nature is governed by laws. The idea that the explanatory terms of natural phenomena are universal, necessary and impersonal laws which can be formulated quantitatively, replaced the Aristotelian emphasis on the ‘nature’ or the ‘form’ of a thing. The Aristotelian explanation placed individual objects and phenomena at the center of attention and considered their cause of change internal, namely, the aspiration to realize potentialities. Grosseteste’s concept of ‘form of corporeity’ and Bacon’s concept of ‘species’ contributed significantly to the development of the idea of laws in nature. With the identification of the form of corporeity with light, Grosseteste turned corporeity into a universal principle of both extension and activity. Nature can be now described by general statements about the quantitative behavior of light or corporeity, rather than by the definition of specific natures. On his part, Bacon replaced the concept of corporeal form with that of species. While Grosseteste portrayed a natural world that share a common feature, Bacon sought to describe the activity of that common feature. What unites matter, according to Bacon, is the mode of causal influence which is always conveyed through the propagation of species. The laws formulated by Grosseteste were the laws of the radiation of light; the laws which Bacon drew up were the laws of the propagation of species. In both cases, the formulation was subsequent to an assumption that the material world is unified by common, active, forms.

Religions and Interreligious Dialogue in the Galilee is a theoretical and experiential course designed to give students a deeper understanding of the historical, political, and religious background of Galilee communities, and to experience interreligious dialogue. The course takes advantage of our unique setting to supplement lectures and panel discussions with on-site learning, meeting with leaders and exploring religious sites of the diverse Christian, Jewish, Muslim, and Druze communities. The course will focus on conflict resolution and interreligious dialogue from religious leaders and activists for whom these challenges are part of their daily life. Eligibility The course is open to a limited number of participants. Graduate students, postdocs and research scientists from institutions of higher education of all nationalities are welcome to attend. * The course will be taught in English.