Moves by itself and by another

Aristotle insists both that:

1.) Nature has a principle of motion of itself, as opposed to art, where the principle is extrinsic.

2.) Everything in motion is moved by another, i.e. by something extrinsic.

Some commentators see a contradiction here – but this goes too far.

Responses: 1.) The “principle of motion” in 1 is primarily matter. 2.) Natural things move as instruments do: they contribute some actuality of themselves to the work (e.g. the cut will resemble the saw) but not as primary movers. 3.) Nature is fundamentally an openness to be moved in a certain way by divine action; i.e. it is fundamentally a unique aspect of the exterior procession of God.


  1. E.R. Bourne said,

    April 24, 2013 at 6:41 am

    James, why do we say “principle” of motion? If we take principle to mean ‘source’ or ’cause’ or ‘explanation,’ then how does it apply properly to nature? The cut will resemble the saw, but how can the saw be said to be the principle of motion?

    • April 24, 2013 at 9:37 am

      I hope I’m not talking past you, but my initial response would be this: When we want to understand nature as a principle (and Aristotle wants to do this) we are working from an idea of “nature” as opposed to “art”, where art is taken it the broad sense of some product made by human skill. This is the sense we are using when we speak of “getting out into nature”, i.e. getting out of the city, away from all the things that human beings make, and into that world that does what it does without any human imposition, planning, or oversight. IOW, when I’m walking around Minneapolis I can think something like “human action is the source of all this stuff”. But what is the parallel thought when I’m walking around in the forest? On such an occasion “nature” is the placeholder term for whatever makes the trees keep blooming, the rain keep falling, the leaves fall off in the fall, etc. On Aristotle’s account of all this, this makes “nature” a source within things. Nature is, for him, not an object – the bloom is not “nature”, nor a tree, nor even a stand of trees, but whatever power it is that makes a bloom, or that makes the tree, the stand of trees, or the forest fire that wipes them out. Nature is what plays the role in the forest that construction firms or city planners play in the city.

      That last example forces one into seeing that Aristotle has a two-tier account of nature as a principle. Just as to explain the construction of each building is not the same thing as to explain how the totality of buildings is arranged to make a city (say, with various zoning areas, water and freeway access, and with various monetary and environmental relationships to the things around it) so too the principle in this tree that makes it grow and bloom can’t explain it as a member of an ecosystem. Construction firms and city planners are both sources causes of the same building, but at different levels of universality. This is the idea that Aristotle is working from when he says that man is generated by man and the sun. He was wrong about the sun, and perhaps wrong about there being any universal causes outside of the spiritual world (although the sun is some sort fo universal cause of plant generation, water cycles, weather, etc.)

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