It is commonly assumed about natural philosophy in the Middle Ages consisted either of slavish adherence to Aristotelian philosophy, or the suppression of the study of nature by Christian thought. In light of the reading you have done on the Middle Ages, evaluate these assumptions. What were the methods by which medieval philosophers came to knowledge about nature?

     Common ideas concerning the nature of scientific thought in the Middle Ages are that either a too absolute adherence to Aristotle or suppression by Chirstian authorities severely limited natural study during this time. Upon inspection, it is evident these ideas are incorrect. Although medieval scholars did not discard Aristotelian philosophy altogether, they did expand it and in many cases went beyond its principles guided by reason, observation or Christian doctrine. While scholars subjected themselves to the doctrines of faith, they found great freedom within those bounds and rarely did Church officials intervene to suppress their pursuits.

Bradwardine's Law and theories of motion

    Discontent with Aristotle was especially visible in the area of local motion, which was elevated by Medieval scholars to a place of centrality. John Philoponus was perhaps the first vocal critic of Aristotle's thoughts on moving objects. He appealed to observation to refute Aristotle's claim that the time of fall of an object is inversely proportional to the weight. By considering air agitated behind a stone he also refuted the claim that air is the motive force in projectile motion. In fact, contrary to Aristotle, he rejected the idea of a medium being necessary at all for motion, and considered finite motion in a vacuum to be possible.

     Later scholars still retained Aristotle's 'force and resistance' requirements for motion to occur and devised ways of including them within the moving body itself. This was especially necessary to consider motion in the vacuum, a concept which became essential after the condemnation of 1277. Concepts such as internal resistance and various theories of "impetus" or "mail" were discussed in order to supply the 'mover' necessary for Aristotelian motion. For example, John Buridan thought of impetus as an incorporeal force impressed in a moving object. He associated the quantity of impetus with the speed and amount of matter in the object being moved, and claimed that impetus could only be diminished by resistance. From this one could conclude that an object would continue its motion indefinitely in a void or a medium that offered no resistance. However, Buridan limited his application of this principle to planetary motion. In his view, the motion of the celestial spheres could be explained through an impetus imparted to them by God at creation. Thus, the ongoing role of an unmoved mover was not necessary.

     Thomas Bradwardine discussed many laws of motion as he came to know them. In particular, he thought Aristotle's view of velocity being proportional to force and inversely proportional to resistance was incorrect, since it does not predict the motion will cease when the resistance was equal to or greater than the motive force. To solve this problem, he introduced another relationship, namely that velocity increases algebraically, while the ratio of force to resistance increases geometrically. With the new theory, an increase of speed became impossible once resistance equals motive force.

     Medieval scholars also succeeded in developing areas where Aristotle had little or nothing to say. In Merton college during the 14th century the fundamental concepts of kinematics were established. Aristotle himself did not have a quantitative view of velocity or acceleration. The Mertonians developed these concepts in the framework of intensification and remission of qualities. Velocity became a quality of motion. Uniform motion was defined as traversal of equal distances in any and all equal time itervals. This meant the intensity of velocity would be the same throughout the motion. Uniform acceleration in turn meant equal increments of velocity acquired in equal time intervals. Clearly this means a uniform increase in velocity. From geometrical representations developed by Nicole Oresme, the mean speed theorem concerning the equality of uniform acceleration from rest and uniform motion at the midpoint velocity was proven. These were all entirely new developments. There were even attempts at defining instantaneous velocity, which Aristotle considered absurd.

Cosmology

     Early medieval cosmology bore elements of the thought of Plato, the Stoics, and Christianity, as opposed to Aristotle. Wide access to Aristotle's works were simply not available until the 12th and 13th century. At this point, a great influx of classical thought into Western Europe took place via large quantities of translated works, hitherto preserved and developed by the Arabic world.

     While Aristotelian influence largely supplanted Platonic influence in the cosmological theories of the medieval scholars from this time forward, there were still deviations away from Aristotle's model where it was found incompatible with Christian theology. For instance, Aristotle believed that void space did not exist. Prominent medieval scholars including Thomas Bradwardine and Nicole Oresme, however, argued that void space must exist. They based their idea in part on an argument made by the Stoics, whereby an object pushed through the extreme edge of the cosmos had to be met by empty space. The other basis for the argument was that God was not limited to a finite cosmos, but extended infinitely beyond it.  

      Ideas of properties of the element composing the celestial spheres are also present in texts from the Middle Ages, while for Aristotle, the subject was closed: for him, they consisted of æther, which had no describable properties. In the Middle Ages, by contrast, the spheres were described as "solid," but with varying definitions of the word, including fluid, continuous, and "cristallini lapidis quanta firmitas" (Grant 161). Aristotle's spheres were also altered in light of a Christian worldview. Genesis' account of the world's origins clearly contradicted Aristotle's supposition of an eternal universe, and Aristotle was modified to accomodate a beginning as a result.   

     Genesis offered a foundation for other modifications, as well. Discussion of the firmament as separate from the heaven took place, and as a solution, three spheres were added to the model of the cosmos. They took into consideration the biblical mention of the waters above and below the firmament, and found a place for them on the Aristotelian model as part of the crystalline sphere. This is the second of three spheres added by cosmologists of the Middle Ages: the firmament comprised the innermost and the "Habitaculum Dei", comprised the outermost (Grant 153).

     Furthermore, some of these scholars suggested that the lower unmoved movers were angels or intelligences. All these modifications serve to show that original thought did have a presence in the Middle Ages. It simply took as its form commentary and criticism of earlier texts, showing a thoughtful respect for ground already broken by classical thinkers, but fully capable of disagreement and reevaluation.   

Condemnations and Suppression by Church

    Christianity thus motivated many modifications of Aristotelian theory, and periodically provided sources of tension within discussion in the academic realm; however, its role as an oppressor of scientific thought is often overstated.

    Growing numbers of students and the drive to absorb new knowledge led to the need for organization in the sphere of learning. Founded on the model of local guilds students and teachers formed an association called a university. These were legally autonomous enterprises with legal rights and privileges. The curricula, election of chancellor, and other matters were decided by the current membership, which was largely composed of Masters' of Arts faculty memebers active in the development of philosophy, including natural philosophy. This, and the fact that the degrees were granted by the chancellor after examination by the faculty, made it unlikely for a university to subjugate itself to any attempts of influence from Church officials. The members of a university enjoyed wide freedom of thought.  As Aristotle's works became more widely read and discussed, contradictions to church doctrine unavoidably surfaced. These contradictions prompted a reaction from theologically conservative scholars and clergy. Many of Aristotle's works were condemned, as in the condemnations of 1210, 1272, and 1277 or expurgated in the case of 1231. It would be a mistake, however, to assume that Christian thought greatly suppressed the study of nature. 

     The condemnation of 1210 stated that "Neither the books of Aristotle on natural philosophy or their commentaries are to be read at Paris in public or secret, and this we forbid under penalty of excommunication" (CP 42). At first this would appear to be a sweeping prohibition, but in fact it only applied to the arts faculty at the University of Paris. Theologians still could read Aristotle's natural philosophy. Furthermore, it would be a reasonable conjecture that the banned works were read in private by other people (Grant 43). 

     However, the bans of 1210 and 1231 were short lived since in 1255 lists certain works of Aristotle tha the Universoty of Paris made part of their curriculum. According to Edward Grant no later than 1263 Aristotle's natural books were a major component of the University's of Paris' curriculum (43).

     Finally, in 1272 the University of Paris' faculty members that held master's or bachelor's degrees were made to avoid theological questions or resolve the questions in favor of the faith. Then in 1277 the bishop of Paris, Pope John XXI, condemned 219 Aristotelian propositions stating "Ever since the introduction of Aristotle's natural philosophy into the Latin West in the twelfth century, ecclesiastical authorities had feared its impact on theological studies and Christian belief" (CP 45). People who accepted any of the 219 banned works were punished by excommunication. There could have been positive aspects to the ban of 1277. First of all, a group of followers still existed that adhered to the traditional natural philosophy who either were not ready to accept or did not want to accept Aristotelian propositions (Lindberg BWS 248). Though the condemnation of 1277 did suppress thought to a degree, the condemnations could have encouraged scholars to explore new non-Aristotelian physical and cosmological alternatives (Lindberg BWS 248).  Thus, paradoxically, even periodic attempts at religiously-motivated suppression often resulted in a net advancement in the study of nature. While it is true that the Catholic Church periodically made pronouncements against ideas it did not like, it did not amount to anything like a total suppression of natural philosophy; many of the condemnations were short-lived, and in many cases they were ignored.

   As we have shown, despite common assumptions to the contrary, medieval scholars did not blindly accept the tenets of Aristotelian natural philosophy.  They explored its ideas and expanded upon then, and in many cases they went beyond its principles. Also, the process of natural philosophy was not severely impeded by Christian authority. The University setting allowed natural philosophy to be discussed in conjunction with theology, which led to the evolution of thinking in both fields.  Even periodic bans on philosophical literature paradoxically could lead to innovations in philosophy.