Nicole Oresme and his Philosophies: An Example of Medieval Scientific Thought

However, Oresme was in many ways ahead of this time. Certainly his work serves as powerful ammunition for the historians on one side of the continuity debate --- the side that argues against the depiction of the middle ages as dark and unenlightened, rather trying to show how progress in philosophy, and by extension, science, did not come to a halt turing the first half of the medieval period, and indeed, did not even slow down. Oresme's work and the views he came to hold show very clearly how the centuries before the Scientific Revolution were necessary for the occurence of that event, rather than delaying its arrival.

This is evident upon examination of the many branches of natural philosophy and academic thought in general that Oresme contributed to. He wrote on economics and did social and political commentary, was a high-ranking clergy, and was an advisor to King Charles V. Under the direction of that monarch, he translated Aristotle into the vernacular French, which was an importante step in the language's scholastic tradition. He also wrote on optics, mathematics, and motion theory, and was instrumental in commenting on and extending Aristotle's more sketchy writings.

In fact, it was a uniquely Aristotelian idea that led Oresme to develop his principles of graphing in the De configuratione qualitatum arguably his greatest achievement. He wanted to fuse Aristotle's principles of form and quality with a kind of geometric analyisis, and thus came up with his system of graphing - he called it the "latitude of forms". Pierre Duhem, one of the first historians to study Oresme's work and compare it to that of later philosophers, was very enthusiastic about Oresme's latitude system, and seems to have implied that it precipitated Descarte's writings, centuries later. Upon examination of Oresme, though, this appears to be an exaggeration at best. He did nothing that hinted at the idea of representing a line as an equation (which is not surprising, since geometry was the mathematical idiom of the day, and not until after Descartes would algebra come into vogue) and obviously was not thinking of "functions" in the modern mathematical sense.

That he did not consider these modern concepts is in no way surprising. With medieval natural philosophy so deeply rooted in ancient Greek thought, the only sort of curved object given significance was the circle - we can hardly criticize Oresme for not drawing an imperfect, wavy line on his graph. And even now, the precise definition of a "function" is a fairly esoteric concept. To Oresme, it would have been utterly alien. Nevertheless, Oresme's inspiration to use geometry in any way to represent qualities rather than form was unquestionably innovative.

Innovative they were, but the applications that Oresme seems to have envisioned for this new mathematical tool show that while his ideas were creative, they were still firmly rooted in the aristotelian tradition. Aristotle envisioned objects possesing matter and quality (form), and Oresme saw his latitude of forms as being a way to represent the degree to which a given object held a given form. So to Oresme, color was no different a property than heat or motion, on his latitude of forms. This made the tool a generalized one, but also a singularly aristotelian one. Thus we can see that it would be premature to say, for example, that Oresme's work was a clear precursor to that of Descartes. Oresme failed to see the significance and usefulness of studying this latitude of forms in its own right, while Descartes essentially invented the very process for doing so. Had Oresme recognized the potential power of this graphing system as a tool for pure mathematical analysis, rather than a simple visual representation of nongeometric qualities, it would be more reasonable to say his work preceded Descartes. Still, the fact that we must go to this extent to show the timeliness of Oresme's ideas proves the creativity and probing mind that must have been at work.

But it would also be an exaggeration to say that Oresme followed Aristotle blindly. His writings on motion theory clearly show otherwise. Aristotle's antiperistasis theory is suspicious at best, and although Oremse was undoubtedly not the first to revise Aristotle's opionions on the subject, his revision came fairly close to the modern theory of motion - closer than anybody else at the time, certainly. It is difficult to say how much of his thought on motion was his own, and how much he inherited from Jean Buridan. Buridan was older than Oresme, and possibly his teacher at one point. Buridan's and Oresme's theories are very alike in their use of the term "impetus", referring to a quality of a body that compels it to move, which stays with it until it is acted upon by external means. This sounds suspiciously like the modern inertia principle, but since it's outside the scope of this discussion to determine whether Oresme formulated the thought on his own or was influenced by Buridan, we'll instead pursue another of Oresme's interests: Light.

Oresme's writings on light are more indicitive of the nature of medieval natural philosophy than perhaps anything else he did. They draw heavily on previous work, from Aristotle to his Islam commentators to other medieval philosophers. While his work was firmly rooted in the science of the day, some of Oresme's intuitions on light prove very interesting, since when taken out of their medieval context, they look very modern. It seems possible that if atomism had been an acceptable theory at the time, Oresme's theory of light might've been as near to the modern one as his theory of motion. This is of course pure conjecture, so we'll now turn to the facts as laid out in Questiones super libros Aristotelis de anima, a commentary on Aristotle's De Anima.

To show how Oresme's theory differed from others of the period, it is useful to give a brief overview of the consensus optical theory, which, like so much of medieval natural philsophy, was based on Aristotle's writings on the subject. Philsophers of the day tended to use two Latin terms when reffering to light: Lux and lumen. Aristotle used a single term ("Phos"), and the dual terminology appears to have its origins in Ibn Sina's retooling of De Anima, where he distinguished between two types of light. Luxlumen was the quality of a medium (or body, presumably) which transmitted light. This view of light having a dual nature was dominant through Oresme's age, and it was instrumental in his writings on the subject.

The other principle component of medieval optical theory was the idea of species, which were immaterial instances of the object being seen, propogated successively through a light-bearing medium, and were the cause of sight. Although theories on species were diverse and poorly-explained (even by Oresme himself) they figured heavily in his writings. It is perhaps fortunate for Oresme that he did not spend his time debating the nature of species, since the various arguments surrounding them (dimensionality, corpreality, spirituality) were labyrinthine and baroque, and were ultimately unimportant to the "meat" of optical theory.

Instead, Oresme chose to do his principle work on the reflection, refraction and speed of light. They are based mostly on the Aristotelian tradition, but combine other opinions in fairly interesting and insightful syntheses. Perhaps the most useful of these combinations is the basis of his argument that diffusion and the scattering of light was simply a special case of reflection. This support for this argument came from Oresme's opinion that lumen was simply the species of lux, which was a nice simplification compared to previous theories. The insight that there was no fundamental difference between lux and lumen was revealing, and formed the basis of all of Oresme's subsequent arguments. It's outside the realm of this lowly writeup to go into the details of said arguments, but imagining the current model of light with an Aristotelian slant will nicely sum up Oresme's opinions on the subject.

Oresme's other main topic in his optical writings was the speed of light. Aristotle had said in De Anima that light, since its propogation was not observable, must propogate instantaneously. Oresme defended this theory rigorously, and used an interesting type of argument to do so. After discussing various real-life instances of illumination, he posits what he believes to be an impossible situation. The details of his arguments are unimportant for our purposes; the important thing is that Oresme seems to have formulated a very abstract, idealized principle by using logical reasoning on several real-life examples. When the common conception is that generalized, abstract laws didn't come into use until the Renaissance or later, the fact is that the trend had already been started in the middle ages. Oresme is an excellent example of this trend toward simplification and clarification.

While we've gleaned all we realistically can from Oresme's work in natural philosophy within the frame of a writeup such as this, there are other fields he worked in which are revealing in the context we are examining him. We know he wrote on economics and politics, perhaps what we would now call the social sciences. One particularly interesting work is the Livre de Divinacions, a treatise on divination and astrology. It is revealing for multiple reasons. First, it's written in French, so Oresme is clearly writing to different audience than in his philosophical writings. Also, although it's a critical, and at times downright scathing commentary on diviners and fortunetellers, Oresme is careful to distinguish between the types of astrology he was able to place at least a qualified belief in, and those he expressed frank incredulity in. So already we find what is by modern standards quite a dichotomy. No recent scientist would admit to belief in anything as vague as astrology or divination (Oresme also allowed for palmistry), and would certainly not write seriously on the subject. But Oresme did, and in as scholastic a manner as any other of his writings, drawing from many diverse sources (scripture, classical philsophers, and some arab writers) to support his conclusions.

So here is possibly the best evidence so far that Oresme was not some far-thinking head-in-the-clouds genius (not to slight the man's intellect) but rather deeply involved with his age, and all the concerns therein. Here also (to point the way for research left as an excercise for the reader) is a fascinating example of the Church's relationship with astrology and divination, given Oresme's position as an orthodox clergy.

So we've shown Nicole Oresme to be perhaps the prime example of medieval natural philosophy and scholastic tradition, handily shouldering the burden of scientific thought on through to the Renaissance. It would be a mistake to allow the brilliance of the great thinkers of that later age blind us to the more subtle, but no less important accomplishments of those that came before them.