Notes on the First Way and Classical physics

-Physics never explains motion, it just makes some given mobile larger. Mobile thing A is explained by being linked to B, which gives us only the larger mobile AB.

-The engine moves the wheels, and the wheels in turn move the rest of the car, engine included. At each stage, the motion of one part accounts for another. We co-ordinate one motion with an earlier one. We can push this to the chemical realm too, but only to get the same sorts of explanation. This wouldn’t be a problem if not for motion – or at least the transition from motion to rest –  is the paradigm case of what needs an explanation.

-At best, inertia is an account of why states continue after initiation. So taken, inertia is essentially a secondary cause, preserving the activity of some initiating cause. Inertia not only does not explain the transition from motion to rest it is defined as an impediment to this transition.

-One unwritten history of classical physics is that by placing inertia at the foundation of physics (as happens in Newton’s First Law) we enshrine the fact that physics treats only of secondary causes of motion.

-Newton’s insight is that physics does not explain motion as such but the transition from one state or velocity to another. This does not mean that “change of state” is a tertium quid with the state of motion and rest, but that physics explains the transition of one to the other.

-When Aristotle says that physics is about mobile being, he is speaking about what is given, not what is an object of explanation. The object of explanation in physics is state or velocity transition, not motion. Motion is only an object of explanation in metaphysics.

– A shorter version of the First Way, if “God” is taken as “explanation of nature outside of nature”*

What is, is explicable by something.

What is given is never explained.

Motion is given in nature.


*And if we assume there is more than one such explanation, like angels or souls, then we understand God as the highest possible such explanation. Souls are clearly not entirely outside of nature but are always defined in relation to it (either as forms or movers of the physics) and angels are defined as mediating intelligences – the very word angel specifies the mediating function of delivering a message.

I’m unimpressed by critiques of the First Way – here I’m thinking of Joseph Bobik – which state that it could just as easily conclude to an angel. This would be true only of our idea of angel was not essentially intermediary, but it is. No theory of angels as angels has ever even suspect that they were the highest beings.



  1. D.S. Thorne said,

    January 6, 2015 at 1:52 pm

    In light of Newton, is it better to understand the First Way as accounting for the motion-underlying-inertia (i.e. why should there be motion at all and not rather rest?), or as accounting for motion-as-changes-in-velocity?

    • January 6, 2015 at 3:21 pm

      I think both. Any transition of states or change in velocity. Newton just gives a particular answer to a more general problem of projectiles, however, sc. he can be read as positing a cause of continuance of motion after separation from an initiator, though he very well might not have wanted to do so.

%d bloggers like this: