Prime movers

Aristotle made the number of prime movers, logically enough, equal to the number of prime movèds or mobiles. He wasn’t sure how many such mobiles there were: he had a hunch that there was only one, but the authorities of his time said there were over 50.  What does our physics think?

Presumably energy moves all things before anything else, and so far as we see it as shifting forms and being applied now here and now there we see it as mobile as well. But if this is right, why posit a mover of the energy itself? Isn’t this like positing a mover that makes steam expand, or a mover that tugs metal for magnets? Presumably, steam expands simply by itself, and magnets need no assistance to drag ferrous metal. If energy just is, as the textbooks agree, the ability to do work, and so to move things from one place to another, what help does it need to move anything? Why look for some cause other than this?

Aristotle would probably want to appeal to the ways in which energy not only moves, but is required to have a real and not merely logical unity projected onto something that is of itself merely an unconnected heap. Conservation laws must ultimately be cashed out on the level of the universe, and they presuppose that any form of energy can be cashed in for another form, and we either have to say there is some real cause of this or that the conservation laws are merely logical constructs. But such a cause would have to affect its work without using energy, or else our explanation becomes circular. This seems to require some cause ordering and giving an intelligible structure to energy, or whatever primary reality we posit to account for motion in different modalities.

But perhaps a more direct way to the idea of a prime mover from energy might begin with the textbook definition of energy as the ability to do work. While clear enough for physical purposes, this description glosses over an ontological division between abilities in first and second act. Things have the ability to move others both when they are doing so and when they aren’t, and so defining energy though an ability to move can’t of itself explain why anything is actually in motion; though it will allow us to say that all in motion is moved by energy, and this energy by definition moves it.

On this account of the first mover, it is the being whose essence and activity are identified, i.e. there is no difference between what he is and what he can do. Said another way, the first mover is that which is essentially in second act, that whose ability does not stand equally to action and inaction. Just what we are to make of such a being – if the idea is coherent at all – is not entirely clear, but we seem to be committed to the idea that such a being is either impossible or necessary.


1 Comment

  1. Curio said,

    December 16, 2014 at 8:18 pm

    What do you make of the energy/prime matter connection suggested by Oderberg (and Heisenberg?)

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