Concepts and consequences

In Book IV of the Physics, Aristotle explored the concept of place in search of a rigorous understanding. Rejecting the possibilities of shape, matter and “some sort of extension between the bounding surfaces of the containing body” (221b), he arrived at his famous definition as “the boundary of the containing body at which it is in contact with the contained body” (212b).

When Aristotle later identified motion with the changing of place, he left a significant problem for himself and all who followed. In the Aristotelian/Ptolemaic astronomical system, the outermost sphere of the heavens had to be regarded as being without place. At the same time, it was supposed to move with constant angular velocity in order to bring about the celestial phenomena. These two assumptions – of movement and lack of place – were contradictory: one of them had to be rejected.

In his Or Adonai of circa 1400, Hasdai Crescas criticised Aristotle’s account of place in great detail (not the least of his objections being that the place of a whole would necessarily be less than that of a part of it). Generally speaking, it seems skepticism of the notion of the universe being moved persisted over the years, even being condemned in 1277 at Paris (proposition 49 reading Quod Deus non possit movere Coelum motu rectu. Et ratio est quia tunc relinqueret vacuum).

Copernicus chose otherwise and attacked the idea that the outermost sphere moved. Noting, in chapter 5 of Book 1 of his De revolutionibus orbium celestium, that “every apparent change in place occurs on account of the movement either of the thing seen or of the spectator”, he further remarked that “if some movement should belong to the Earth it will appear, in the parts of the universe which are outside, as the same movement but in the opposite direction”. Galileo employed this same argument much later; that is, that the question of geostaticism versus geokineticism (whether the Earth moves, not the separate issue of where it sits in the astronomical system) could not be decided on the basis of observations because the phenomena produced by moving heavens and a stationary Earth would be the same as the converse (but opposite when seen from “outside”, per Copernicus’ comments). Having explained this difficulty, Copernicus went on to say that “it will not be clear at once why movement should not be assigned to the contained rather than to the container”.

Later, in chapter 8 of the same book, he went on to call the contrary assumption “absurd”, employing the aesthetic argument that “the state of immobility is regarded as much more noble and godlike than that of change and instability, which for that reason should belong to the Earth rather than to the world” (later moving on to his heliocentric appeal, “who would place this lamp of a very beautiful temple in another or better place than [the centre] wherefrom it can illuminate everything at the same time?”). Although not the only motivation for his work, it is obvious from his own testimony, as well as the ongoing concern at the incompatibility of the motion and lack of place of the outermost heavenly sphere, that Aristotle’s carefully argued conception had consequences well beyond its original use.

This, of course, is the point: the choices we make in our underlying concepts delimit what we can achieve with them subsequently, unless we regularly subject them to scrutiny. No one accorded this vital part of science more importance than Einstein, who, in his foreword to Max Jammer’s study, declared that “… in the interests of science it is necessary over and over again to engage in critique of these fundamental concepts, in order that we may not be unconsciously ruled by them.” This is a lesson that also appears worth learning “over and over again.”

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2 Responses to Concepts and consequences

  1. Awet says:

    Einstein’s point seems to indicate a foundational concept of knowledge in which the grounding concept determines the shape of the entire framework. Could this be avoided if the system of knowledge has a different shape, a more holistic one than a hierarchical one?

    • Paul Newall says:

      Well, I agree with you that foundationalism is “generally quaint, romantic at best, and ultimately untenable”. However, I think the idea here is more that concepts delimit what we can learn and hence we need to continually reassess them to test these boundaries. In a future entry I will consider this advice in light of Kuhn’s work.

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