An example of an abandoned idea

Self motion was a fundamental question for pre-classical physics. It divided any number of schools (Plato and Aristotle, Aquinas and Scotus) and the problem was disputed at great length. But the question of self-motion is simply untranslatable into modern physical or biological categories. How would Newtonian self-motion be different from Relativistic or quantum self motion? What would the difference between Darwinian and Lamarckian theories look like? Both questions are absurd – you might just as well try to distinguish the theories by their color.

But for all that, self-motion is still a live question. It certainly seems like it happens, i.e. that it is a physical fact, but what sort of theoretical edifice would allow for its truth? For that matter, what sort of edifice could prove that it does not happen, or even that speaking about it is meaningless?

This question about self-motion spills over into other considerations: responsibility requires self-motion, which ties the idea to freedom; again, self-activity is the activity of a self, which ties the question to the definition of a self or, in the case of human beings, the account of a person, etc. Again, self-motion is exactly what the ancients used to define life as opposed to nature, and so in losing any meaningful account of self-motion we will lose any meaningful sense of the difference the ancients saw between the living and the non-living (or merely physical). This in turn affects the sort of reductions to physics we think are possible…

You get the idea. But self-motion is just one example of many. We abandoned the idea after becoming interested in other things.


  1. sdcojai said,

    March 24, 2013 at 1:14 am

    I completely agree with you that self-motion is still an important question. In fact, I think it has more, rather than less, significance than some of the ancients thought, and that it is a key to cosmology. The reason why I think these things is because it is fairly demonstrably false that inanimate bodies are purely passive with respect to their own location, as the ancients assumed …So I wonder if it is exactly accurate to say that we abandoned the idea after becoming interested in other things … at least if “after” means “because.” It seems more plausible that we abandoned the idea because we didn’t know how to keep up with it, so to speak. More generally, we abandoned any serious attempt to keep science and philosophy as genuine parts of an integrated endeavor.

    • March 24, 2013 at 4:09 pm

      I have two responses. They’re inconsistent with each other but they both point to some difficulty with a modern account of self-motion. Some things here are consistent with what you’re saying, though I have a more skeptical view of the possibility of integrating philosophy and science.

      1.) I don’t see how to articulate the difference between self-motion and moved by another in contemporary categories. Illustrate the problem like this: if you asked me to write a chapter on self motion in Plato, Aristotle, or anyone who did physics until a few centuries ago, then the debate would be well defined, the relevant concepts and texts in play well-known, and the outcome of the debate would be of great significance to the various sciences. If you asked me to write a chapter on the difference between self-motion and motion from another for a modern biology or physics textbook, there would be no contemporary debate to point to, no set of concepts that the science used that could articulate the problem, and it’s hard to see how the outcome of the debate would change anything in what these sciences were trying to do. I’m reminded of the end of Newtons second corollary to the Laws of Motion, where he speaks indifferently of levers, screws, and the limbs and joints of animals, i.e. in the context of what he’s trying to do (which is something like “to bring all motions under simple laws or axioms of motion”), there’s no relevant difference between the living and the non-living, the self-moving and the non self moving.

      I’m limited here in my understanding of the history. For all I know, there was a vigorous debate about self-motion in the 19th century within the modern context. I’m skeptical though.

      2.) [I]t is fairly demonstrably false that inanimate bodies are purely passive with respect to their own location, as the ancients assumed

      But isn’t the passivity of things a tacit point of agreement between (some) Ancients and the moderns? It seems to me that “to know” in the modern sense is tied to the ability to make something, that is, to be able in principle to assemble it and control the processes that make it come to be and work. In practice, this means you are able to isolate energy source from the system that channels it or responds to it. Energy (or, for Newton, “force”) is purely active but all the things that one studies in nature are mere conduits of it. On this account, all “things” are purely passive, just conduits for free energy or negentropy or something like that.

      The ontology in play here seems to be that everything active is directionless and everything that goes anywhere is merely running off it. If you made things “self-movers” you would, in modern terms, have to introduce an energy source that was directed or responsible, or something like that.

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