Another approach to the First Way

As a BARBARA syllogism, the First Way is:

Everything moved by another is moved by a first, immobile mover.

Everything in motion is moved by another.

Everything in motion is moved by a first, immobile mover.

Now if we step back from the controversial fact that this is supposed to be proving the existence of God (which, for whatever reason, always tends to trigger logical hyper-scrupulosity), we might take it as a rather uncontroversial proof for either laws of nature or something like energy.* Physics is in the business of explaining why things move around, and it always explains things in terms of some first thing that always remains unchanged in itself. If you see a bunch of things fall in the inverse square of the distance, you account for this by saying there is some law of gravity, and this law of gravity doesn’t move around – whether in the inverse square of the distance or in any other way. Again, if you see things moving around, you account for their motions in terms of energy or something like it, and this energy doesn’t ever change qua energy, but only manifests itself in different modes. So the major premise and the conclusion seem to be uncontroversial claims – which gives us the minor premise for free by logic alone (though this is usually the most controversial premise when the FW is usually presented)

But even if the laws of nature or something-like-energy are immobile in themselves, neither suffice to explain why anything is actually in motion. Laws of nature only give us actual motion if we help ourselves to initial conditions, since laws are ways of relating initial conditions to outcomes. Energy also doesn’t explain why something is actually moving, since energy is the ability to do work but a thing has the same ability to do work whether it is actually working or not. And so while physics explains things in motion by relating them to the immobile, the immobility it attains to is still not adequate to account for the things of experience, leaving us having to add something to physics in order to account for the very thing it’s trying to explain.

Read in this way, the FW is an apologia for metaphysics, that is, for a science distinct from but contiguous with physics which carries on the explanatory enterprise to its conclusion. Physics carries the explanation as far as it can go along the line of things that can be given to sensation, which allows at most for things that interact with something we can sense either directly or through an apparatus. The physicist’s job is done as soon as he hits on some unseen power that works interactively, that is, the power of an entity that cannot exist apart from something at least potentially sensible, like laws of nature, which are defined with physical and sensible things (like meters, masses, speeds, etc.).


*”Something like energy”, i.e. maybe mass-energy, or whatever might wind up unifying all the fundamental forces, or what might end up unifying the fundamental forces with dark energy, or what might unify the dark energy-fundamental forces thingamajigger with something else we end up discovering. At any point on this progression, energy is something remaining the same in itself and yet manifesting in diverse modes to give us diverse forces.


  1. JeffC said,

    December 19, 2014 at 11:22 am

    I actually wrote my MA thesis at the Center for Thomistic Studies in Houston on much this same topic (with a different entry point into the discussion). I think you’ve very succinctly explained why the motion proofs are part of natural philosophy, yet lead us to metaphysics.

    Some want to argue that the motion proofs are part of metaphysics. This begs the question, because how can we be doing metaphysics until we know that something beyond the physical world exists. Once we conclude to the existence of an unmoved-mover in natural philosophy, we can move into a further discussion of the implications of that conclusion in another science: metaphysics. The FW then, stands at the door between one science and another.

    • December 19, 2014 at 1:35 pm

      how can we be doing metaphysics until we know that something beyond the physical world exists?

      This is certainly true for STA, and it is probably the safest and most minimalist epistemology, but it depends on rejecting the Ontological Argument, a sensus divinitatis, various logics that see real possibility as failure to see a contradiction in something, various definitions of (natural) science that define the object of science in opposition to subjectivity and/ or secondary qualities and/ or qualia, some versions of the Cogito, the Eastern Orthodox insistence on the unity of the mystical and the natural in lived experience (and a good deal of Eastern Theology, like Schmemann’s symbolism), and maybe half a dozen other claims and arguments (like all Idealisms). Again, St. Thomas does reject all these things, but all sorts of arguments are thrown against him for doing so. I mention this because no one has yet succeeded in finding a common thread in all these things STA rejects, but I’m pretty confident there is some one thing making them all X. It would make for a fascinating study to consider the various interactions and complaints of Thomistic and X-ist philosophy.

    • December 21, 2014 at 8:28 am

      Can y’all expand on how physics leads to metaphysics? I am assuming that you don’t mean physics naturally leads to metaphysics in that the concept physics somehow contains in it the concept of metaphysics, either virtually or essentially– as in the concept of a cube contains within it the concepts square and rectangle, but not circle. So in what way does physics lead to metaphysics?

      • December 21, 2014 at 12:54 pm

        In this post all I mean is that metaphysics continues the explanation of physical things. My claim is that physics – or at least any physics that explains through something like energy or Laws of nature – does not suffice to explain why things are actually moving.

        We do physics because we’re confident – for whatever reason – that we can give causes of moving things. there’s no reason for this to stop just because the resources of physics give out.

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