The Nature of Light

November 16, 2021

Part 10 of a series on Whether There Was a West.

I wrote a post today about how divergent Greek philosophy really is, but it got too long, so first I want to look at the history of science as it relates to the Greek schools.

Before Newton, the Greek schools (Epicurean, Aristotelian, Platonic) had no consensus about the nature of light.

Here is Thomas Kuhn, again in Structure of Scientific Revolutions (1962), on how “Western” thinking changed with Newton (emphasis mine):

These transformations of the paradigms of physical optics are scientific revolutions, and the successive transition from one paradigm to another via revolution is the usual developmental pattern of mature science. It is not, however, the pattern characteristic of the period before Newton’s work, and that is the contrast that concerns us here. No period between remote antiquity and the end of the seventeenth century exhibited a single generally accepted view about the nature of light. Instead there were a number of competing schools and subschools, most of them espousing one variant or another of Epicurean, Aristotelian, or Platonic theory. One group took light to be particles emanating from material bodies; for another it was a modification of the medium that intervened between the body and the eye; still another explained light in terms of an interaction of the medium with an emanation from the eye; and there were other combinations and modifications besides. Each of the corresponding schools derived strength from its relation to some particular metaphysic, and each emphasized, as paradigmatic observations, the particular cluster of optical phenomena that its own theory could do most to explain. Other observations were dealt with by ad hoc elaborations, or they remained as outstanding problems for further research.

For Kuhn, there is a pre-paradigm period in which each school argues with the other schools about fundamental questions. In physics, Kuhn sees the first consensus coalescing with Newton. Einstein represents a scientific revolution, after which the consensus is replaced with a new one, after a period of crisis.

In 1550, there were many competing theories, each of which explained some aspect of light better than the others. But by 1850, if you thought Newton was wrong, you were suddenly not a scientist.

For Kuhn, what is surprising is not that different branches of science debate one another. What is surprising is that this debate ever ends. I cover this in more detail in this part of my thread, but here’s the relevant section:

No wonder, then, that in the early stages of the development of any science different men confronting the same range of phenomena, but not usually all the same particular phenomena, describe and interpret them in different ways. What is surprising, and perhaps also unique in its degree to the fields we call science, is that such initial divergences should ever largely disappear.

For they do disappear to a very considerable extent and then apparently once and for all. Furthermore, their disappearance is usually caused by the triumph of one of the pre-paradigm schools, which, because of its own characteristic beliefs and preconceptions, emphasized only some special part of the too sizable and inchoate pool of information.

I want to suggest that this kind of homogenizing purge is characteristic of the West — not just of science, but the whole “West”, retrospective myth though it is.

Bryan Kam

I'm Bryan Kam. I'm thinking about complexity and selfhood. Please sign up to my newsletter or see more here.