Natural philosophy, medieval
Authors: Sylla Edith Dudley 
Published: September 2018

Medieval Latin natural philosophy falls into two main periods, before the rise of the universities (mainly in the twelfth century, when works were produced in connection with aristocratic patrons, monastic institutions or cathedral schools) and after their rise. In the earlier period, the dominant Greek influence is that part of Plato’s Timaeus which had been translated into Latin and commented on by Calcidius. In the university period, the central works are those of Aristotle, often together with commentaries by Averroes.
Before the twelfth century, there was very little that could be described as natural philosophy. Such work as existed fell mainly into the genres of natural history (encyclopedic works using Pliny and the like as sources), didactic works (perhaps following a question and answer format on the model of Seneca’s Natural Questions) or biblical commentary (especially commentaries on the Hexaemeron, or six days of creation). In the twelfth century, however, there are a number of original texts that may be considered as natural philosophy; examples include William of Conches’ Philosophia mundi (Philosophy of the World), Bernard Sylvester’s Cosmographia or Hildegard of Bingen’s Scivias (Know the Ways). Greek natural philosophy also reached the Latin West through its influence on medical works and on art, for example on drawings of the cosmos, heaven, angels and hell.
The high and late Middle Ages (thirteenth and fourteenth centuries) was perhaps the preeminent period in all of history for natural philosophy. Natural philosophy was an official area of study in the arts faculties of medieval universities, alongside and distinct from the seven liberal arts (the trivium – grammar, rhetoric and logic – and the quadrivium – arithmetic, geometry, astronomy and music), moral philosophy or ethics, and first philosophy or metaphysics. As a subject of the arts faculty, natural philosophy was also defined as distinct from the subjects studied in the graduate faculties of theology, medicine and law.
The most common approach to natural philosophy in the thirteenth and fourteenth centuries was to comment on, or to dispute questions arising from, the natural works of Aristotle, especially his Physics, On the Heavens, On Generation and Corruption, Meteorology and On the Soul, as well as his various works in biological areas and the so-called Parva Naturalia, a group of short works on psychological topics. Medieval investigations of the cosmos that were largely mathematical – for example, most of astronomy – were considered in the Middle Ages to belong not to natural philosophy but to the quadrivium or perhaps to the so-called ‘middle sciences’ (such as optics, statics or the newly developed ‘science of motion’). What little medieval experimental science there may have been (for instance that appearing in Peter Peregrinus’ De magnete (On the Magnet), in Frederick II’s De arte venandi cum avibus (On the Art of Hunting with Birds) and perhaps in some works on alchemy) seems not to have been done within the university setting. In the fourteenth century the new methods of medieval logic (supposition theory, propositional analysis or exposition, rules for solving sophismata and so on) are prominently used in natural philosophy.
Thirteenth- and fourteenth-century natural philosophy began with the general assumption of the Aristotelian world view, but later medieval natural philosophers did not hold to the Aristotelian view rigidly or dogmatically. In some cases, Christian faith seemed to contradict or to add to Aristotle’s ideas, and natural philosophers tried to resolve these contradictions or to make the appropriate additions, as in the case of heaven and hell and angels. A number of difficulties, inconsistencies and sticking points in Aristotle were special subjects for discussion and received new resolutions as time went on.
Within the medieval university, natural philosophy was considered to be a part of general education, but it was also thought to be useful as a tool for theology and medicine. In northern universities such as Paris and Oxford, some of the most fundamental original work in natural philosophy was done in connection with the investigation of theological problems, for which natural philosophy, together with the other disciplines of the arts faculty, served as important aids. In Italian universities, where faculties of theology were less prominent or non-existent, natural philosophy was similarly tied to the resolution of medical questions.
European libraries contain many manuscript commentaries on Aristotelian works that still await modern analysis. The medieval university system did not as a rule identify, encourage or reward originality or uniqueness. Many natural philosophers claimed to be explaining Aristotle’s meaning, even when they were introducing a novel interpretation of or variation on his ideas. When they made use of the ideas of earlier commentators, they rarely mentioned them by name. What we now know about medieval natural philosophy is not a mirror reflection of what happened in the thirteenth and fourteenth centuries, because modern scholars have chosen to study those subjects and individuals relevant to their own present situations: Dominicans have emphasized the history of Dominican natural philosophy in such thinkers as Albert the Great and Thomas Aquinas, Franciscans have studied Franciscans such as John Duns Scotus and William of Ockham, historians of science have studied those individuals who had something to say about the subjects of modern science such as bodies, forces, velocities and resistances, logicians have studied logic, and so on. Because natural philosophy as such is not the focus of attention of many modern philosophers or other scholars, much medieval natural philosophy remains unread, sometimes in large-scale and handsomely produced commentaries on Aristotle’s works, sometimes in hastily scribbled student notebooks.