Medieval Physics in Oxford: Reflections by Brian Tanner

20150628_192910 (1)When Jo Ashbourn, Senior Tutor at St Cross College, Oxford asked me to summarize the proceedings at the end of a one day conference on Medieval Physics in Oxford, I responded enthusiastically. Several weeks later at the start of what proved to be an interesting day, I was less than certain that it had been a wise decision.

The over-subscribed meeting, sponsored by the British Society for the History of Science was one of a series of one-day conferences run by St Cross College. Its aims were firstly to challenge the commonly held view of the prolonged gap in the progress of Western civilisation’s understanding of the natural world by examining the place of physics in the medieval world-view. Its second aim was to review the contributions of the medieval scholars working specifically in Oxford and demonstrate the evolution of their activity from its theoretical, theological origins into the activity using mathematics and experimental observations which forms the basis of modern physics.

The Ordered Universe Project was well represented both amongst the participants and in the proceeedings. Grosseteste featured strongly in the morning session, chaired by Professor Robert Iliffe of the University of Oxford. James Hannam, author of God’s Philosophers, described the personalities associated with medieval physics in Oxford, their work and their underlying motivations. His comments on Grosseteste’s scientific legacy were amplified by our own Jack Cunningham of Bishop Grosseteste University, Lincoln in an enthusiastically delivered talk on Grosseteste’s Oxford years. Jack pointed out Grosseteste’s importance in Oxford in the early 13th century by highlighting that the 1234 Royal Mandate to arrest all prostitutes was delivered to Robert Grosseteste and Roger Bacon. He also told the story that the magnitude of Grosseteste’s intellect was rumoured to arise from him owning a brazen head to which he asked questions and received answers. There was a 16th century story that the brazen head got broken, resulting in Grosseteste changing his focus from science to theology. The morning concluded with a description by Brian Clegg of the work of Roger Bacon and an examination as to why Bacon has become so famous in comparison with other Oxford scholars such as Grosseteste. This appeared to be a mix of the volume of his scientific output and the growth of a legend around him.

After lunch, the session was chaired by the Ordered Universe team member, Dr Pierre Dechant of the University of York. Pierre presided over a demonstration of a number of astronomical instruments by Oxford University’s Allan Chapman, the day being concluded by a talk by Nicolas Weill-Parot of the Université Paris-Est Créteil on the historical significance of late medieval physics in Oxford.

Following some frenetic Power Point creation during the tea break, I was charged with summarizing the key points emerging from the talks and trying to draw some general observations on the day. On the contribution of the Oxford scholars, it was noted that it was very strongly based on Greek and Arabic antecedents. The challenge, in questions to James Hannan and Jack Cunningham, of what new science had emerged from specifically from Oxford was strongly defended by Jack in the context of Grosseteste’s understanding of the role of refraction in the formation of the rainbow. However, as set out by Jack in his talk, the chronological issues associated with Grosseteste’s whereabouts when he wrote the scientific treatises leave the specifically “Oxford” contribution in some doubt. Bacon’s argument that science was essential prior to study of theology, expounded by Brian Clegg, was an important contribution to the development of the curriculum, particularly that of the Franciscans. It was apparent from the talks of both James Hannan and Allan Chapman that although medieval university science made a negligible contribution to technology or practical application, it was itself clearly influenced by technological developments outside of the university environment.

GrossetesteGrosseteste’s emphasis on unification of explanation of natural phenomena, illustrated by his link between light and matter, and between light and sound, resonated with points made by most speakers. Jack Cunningham of course highlighted Grosseteste’s theory that light is the first form, giving dimension to the universe and that in understanding nature we should recognise that nature operates in the most efficient way possible. The uniformity of nature reflected the benevolence of the Creator. In this context, James Hannan emphasised the harmony between science and theology in this period. A somewhat different slant on unification came out in the strong links that existed between Oxford and Europe at this time.

I compared Grosseteste’s four substantial contributions to scientific methodology with those of other Oxford scholars described by the speakers. Grosseteste described the method for reaching a universal principle from repeated observations under controlled conditions and developed the principle of falsification for testing theories. His third key contribution was the development of the method of reducing a complex and intractable problem into simpler, tractable components. His fourth development, usually associated with the later Oxford scholar, William of Ockham, was in the argument that the explanation needing fewer suppositions and premises was the best. James Hannan and Brian Clegg had both emphasised that the 13th century saw major development of the use of mathematics to explain the natural world and although not using arithmetic or trigonometry this is entirely consistent with the highly mathematically structured treatises of Grosseteste. Allan Chapman had drawn out the application of mathematical instruments to reach quantitative conclusions over this period and showed how such activity operated in the prevailing technological culture. He illustrated this thesis by pointing out that the first treatise on how to use a mathematical instrument was produced by Chaucer in Oxford. The presence of three medieval astrolabes in Merton College is suggestive that there was expertise in scientific instrument making in Oxford during the 14th century. Astrolabes are specific to location, indicating that the key brass components were made locally.

Brian's PennyQuestion of “experimentum” and its interpretation either as experience or experiment had been highlighted by Jack Cunningham. I am afraid that I could not resist wading in and discussing the visibility of hidden object when water fills a vessel due to refraction. In Grosseteste’s De iride, he describes the experiment, quoting from Pseudo-Euclid’s Catoptrica. However, a later copy describes not an “object” but specifically a “coin”, suggesting that the demonstration was certainly done. On the other hand, if Grosseteste had known the experiments described in Ptolemy’s Optics or Alhazen’s works, it is unlikely that he would have formulated his proposition that the angle of refraction is always half the angle of incidence. What we would recognise as experiments do appear by the end of the 13th century but it is not clear that they featured earlier.

A fascinating comment concerning funding for science captured the audience’s imagination. Just as now, surplus wealth was necessary for scholars to have time to devote to intellectual enquiry. They needed leisure and time for thought and such conditions did seem to have developed in medieval Oxford with a great enhancement of economic activity in the 14th century. The transmission of the legacy of the Oxford scholars to other institutions in Europe was hinted at in the presentations. The school in Oxford founded by Grosseteste did, through people like Roger Bacon, indeed influence scholars such as Witelo and Dietrich of Freiburg in the development of the theory of the rainbow based on total internal reflection inside individual raindrops.

To end the summary, I gave the “take-home” warning, already articulated by Nicholas Weill-Parot that we must understand medieval science in the context of its time. Attempts to superpose a modern world-view and seek to identify discoveries ahead of their time must be resisted as anachronistic.

Brian Tanner

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