
Peter Lombard
'For whether it commences from zero degree or from some [finite] degree, every latitude, as long as it is terminated at some finite degree, and as long as it is acquired or lost uniformly, will correspond to its mean degree [of velocity]. Thus the moving body, acquiring or losing this latitude uniformly during some assigned period of time, will traverse a distance exactly equal to what it would traverse in an equal period of time if it were moved uniformly at its mean degree [of velocity].'
William of Heytesbury
I was amused to see Richard Carrier’s horrified reaction to the suggestion that Thierry of Chartres’s commentary on Genesis had anything to do with science. For Carrier, Thierry’s effort - which attempted to set out the creation of the world using Platonism and Aristotelian logic – ‘isn't even remotely scientific behaviour’ and ‘almost in every way exactly the opposite of doing science’. In fact it is so the antithesis of science it even confirms Jim ‘no beliefs’ Walker’s graph of ‘scientific advancement’ which depicts the Christians of the early to high Middle Ages as a bunch of indolent, sub-literate, bible bashers.

Furthermore, the natural philosophers of this period were not like modern scientists, though we are often guilty of projecting our worldview onto theirs. Their explanation of the natural world was inseparable from their philosophical views, their religious beliefs and their theological assumptions. The full historical picture is therefore highly complex because science, philosophy and theology are so inextricably entwined. If we want to understand it, we can’t simply go back through the past giving ‘gold stars’ to those who conform to our expectations and red lining those who don’t. It is true that if you submitted Thierry of Chartres's Hexameral treatise to the scientific journal ‘Nature’ today it would doubtless be dismissed as ‘hand-waving’ and ‘kookery’; but in the context of the early Middle Ages these commentaries provided a framework and a context in which natural philosophy could be done and they undeniably furthered the study of the natural world.
Another good example from the Middle Ages is what we would today recognise as the science of the kinematics (dynamics, or causes) of motion. As documented by Edward Grant in ‘The Foundations of Modern Science in the Middle Ages’, this actually seems to have developed out of a purely theological speculation made a couple of centuries earlier. In the middle of the Twelfth century, the theologian Peter Lombard asked a question about how grace or charity could be increased in a person. Could a person become more filled with grace or more charitable?, or as Peter put it ‘whether it ought to be conceded that the Holy Spirit could be incread in man [that is] whether more or less [of it] could be had or given’. His answer was that, since grace and charity are gifts of the Holy Spirit, they are absolute quantities and cannot vary. This means that when a person becomes more charitable it is only because of his participation in absolute charity.

Aristotle had said that there were three kinds of motion. Motion of place, from point A to point B. Motion of quantity, when the quantity of something changes; and motion of quality, for example when an apple turns from green to red. Once the notion of intention and remission had been applied to notions of quality (the amount of grace or charity in a person) it could also be applied to motions of place; or in other words an object moving from a to b or moving with increasing speed. This meant that speed could count as a ‘quality’ and we can therefore add speed with conceptual validity. As time went on, the scholastics who debated this point became less and less interested in the theological and ontological aspects and more interested in the mathematical aspects of qualitative change.

They also devised the mean speed theorem (which according to Carrier’s definition is a ‘renaissance’ invention; and in any case, it wasn’t used properly until the scientific revolution when some Gibbon-eque ‘scientific values’ mysteriously permeated society and ousted the faithheads; in any case Archimedes probably came up with it, we just don’t have the evidence yet and arguments from silence are invalid etc etc..).
The mean speed theorem goes something like this. Assuming that there is uniformly accelerating motion (a body going from zero to say 60 miles an hour) a body will travel the same distance in the same time as another body moving at a constant velocity which is the mean between the starting velocity and the final velocity of the first object. In other words, if we have an object that is starting at a speed of zero and it goes to a speed of eight, it will traverse in a given interval of time in the same space as a body moving with a velocity the mean between zero and eight (four). William of Heytesbury’s version from ‘Rules for solving sophisms’ goes as follows:
“For whether it commences from zero degree or from some [finite] degree, every latitude, as long as it is terminated at some finite degree, and as long as it is acquired or lost uniformly, will correspond to its mean degree [of velocity]. Thus the moving body, acquiring or losing this latitude uniformly during some assigned period of time, will traverse a distance exactly equal to what it would traverse in an equal period of time if it were moved uniformly at its mean degree [of velocity].”

We therefore need to take an extremely wide view when reading the history of science. You cannot simply go through intellectual history, isolating things we recognise as scientific. If you do that, you completely miss the historical context and the causation behind things. You miss an enormous amount of the influences that come in and originate from what we would today segregate as non scientific activity. Sure, it might be 'not even remotely scientific behaviour'; but so what?; appearances can be deceptive.
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