Note on Aristotle’s Physics

Aristotle argued that the natural world is an object of stable and permanent knowledge. The opinion was the minority one: most thought that the knowledge of the world was simply doxa, that is, a falsifiable truth that had no perfect objectivity and therefore no permanence. This absence of perfect objectivity meant that the only knowledge of nature we could have needed to rest on stipulated realities and  hypotheses. While Aristotle wrote a lot about nature that was based on doxa, his Physics was thought to contain more permanent truths about nature, since it was supposed to be based on common experience, which was thought to be more or less true and not open to critique by specialized experience. But in turning to the Physics in search of such truths, all one  finds is a series of conclusions that are either false or of no value, and by “of no value” I mean the term as Aristotle himself used it: “definitions which do not enable us to discover the derived properties, or which fail to facilitate even a conjecture about them, must obviously be… futile (De anima, I:1)” If the value of definitions is from the power they give us to derive new properties and facilitate conjecture, then we must admit the truth of any number of things that nullify the supposed truth of common experience. For example, it is more valuable to identify rest and motion (as happens in inertia) or magnitude and time (as happens in Relativity). Again, we should affirm that things with no parts can move (Like electrons. The premise is not inconsequential – it grounds Aristotle’s proof for the existence of God) and we should deny that anything in motion needs a subject of notion (a light wave is not some thing waving – like aether) and that, as a consequence to this, magnitude is not the foundation of physical things, that is, a sort of substrate that supports all activity. It goes without saying that we can’t imagine any of these things or visualize what nature must be like if it is like this, but this seems to be the most fruitful way to consider it. This seems to prove that common experience of physical things is really just humanized experience, that is, the subjective conditioning of phenomena common to the human animal. Had we evolved to move at faster speeds or with a body closer to the Planck scale, our common experience of the natural world would be nothing like it is now. The truths that would remain the same would either be taken from mathematics or metaphysics.

And so while Aristotle deserves credit for making the strongest case that there is some permanent knowledge of nature, the project failed, and we have yet to fully mine all the truth that we can get out of its failure.



  1. Mitchell said,

    March 14, 2012 at 8:15 am

    First of all, Inertia does not have a proper definition, the constraints of which Aristotle laid out in his Posterior Analytics. At the most, it is a postulate. Also, definitions of motion are extremely rare. Aristotle’s is the only one I know of that is actually a definition. Most of them follow this formula (motion is what things that move are doing). Furthermore, do electrons have no parts? Is this true? Or do you mean distinct parts.
    Really, the lack of true definitions in science is so great that one wonders what science can actually prove. The answer is already contained in the scientific method. “Science cannot prove anything.” It can only make hypotheses to greater or lesser degrees. Here I use hypotheses in the Aristotelian sense.

    • March 14, 2012 at 10:09 am

      If the lack of a proper definition rules out inertia, it would rule out Aristotle’s own definition of motion too, since Aristotle himself denies that there is a genus of motion, and even if there were, “potency as potency” is not a genus. So pick: either we keep Aristotle’s definition and allow inertia (which, to be honest, causes extreme problems for A’s theory) or throw out A’s definition for being improper (which throws out perhaps the one part of his physics that someone might believe.)

      We know what it means to spin an electron, and no amount of spin causes it to separate into component parts, though every other particle we spin does separate. So the electron is different from any other particle we find with component parts. We do not, moreover, follow the logic of the argument if we say it “has component parts that do not separate”, since the very test for component parts is their separability.

      I agree that science uses hypotheses in Aristotle’s sense. But to say from this that it proves nothing is a standard of proof that Aristotle himself denies. He wrote a whole book on dialectical proof. If you meant that modern physical science does not produce a body of demonstrations that Aristotle describes in APo, all formalized into a single system, then I would agree with that too, but it is also the case that there is no such science. If you want to argue that there could someday be such a thing, this is all very well, but there is no such thing now, and all attempts to create it (and Aristotle’s Physics was certainly not the only one) have met with failure. You can still try to find such a thing or wait for it to come, but after this amount of failure it is not the reasonable play.

  2. Mitchell said,

    March 15, 2012 at 8:08 am

    Aristotle indeed says that there is no proper genus of motion, in the sense that it does not belong properly to any one of the ten categories. When placed in the categories, however, the species of motion come to be. For example, motion in the category of substance is called generation and corruption, motion in the category of quantity is called growth and diminution.
    I think the genus in the definition could be the “actuality of what exists in potency.” The species making difference would be the “as such”. This makes sense as both a tree that has grown and a tree that is growing are “actuality of what exists in potency”, since both the tree growing and the tree grown were in potency and are now in actuality. The tree which is growing, however, differs from the tree which has grown by being the “actuality of what exists in potency as such.” The other definitions of motion follow this pattern. “Act of the mobile as mobile” as it differs from the “Act of the mobile as paperweight.”
    Meanwhile, we cannot get rid of something which we do not have. And the tendency of an object in motion to remain in motion unless acted upon, is not a definition. Especially since it goes against the idea that a finite mobile cannot be moving through an infinite distance, because (one of my favorite Aristotelian principles) “you cannot be doing what cannot be done.” Since Aristotle’s definition is not improper, we must therefore throw over inertia.
    So electrons do not have component parts. Do they have size? If so, that is great, and Aristotle will not stand in the way of anyone saying that they move. Still, remember that these electrons are probably the least known of all the things we experience. Even spinning them sounds like some sort of mathematical analogy for what is actually going on. Besides, spinning is weird. Is it motion of the whole or the parts? The point is unimportant.
    Aristotle was most impressive for his ability to find the right method for the right science. He was not like Descartes, who wanted one method and one system of knowledge for all things, but rather one who recognized how to approach each subject. Dialectical proofs have their purposes. One of their highest uses is to discover definitions. The scientific method itself recognizes its own limitations as proudly declares that it cannot prove anything to be true, only most likely. Unfortunately the sciences have been broken by ideas such as yours, that Aristotle’s Physics is useless in the realm of science and should be banished to the “Humanities” as if one thing can be true in science and another true in philosophy. It could just be that science wants philosophy out of the room so they can play with electrons and talk about spinning them without philosophers asking them what they mean by spinning. It would of course make things move more slowly and more complex, but that is the way with the Truth. Not all attempts have been met with failure, rather they have been ignored and passed by. I don’t deny that science has done some wonderful things, but I am loath to ascribe to it the complete understanding of those same things.

    • March 15, 2012 at 12:16 pm

      I skip over your argument about act since it concedes that the definition does not have a proper genus or difference.

      [Inertia is false] since it goes against the idea that a finite mobile cannot be moving through an infinite distance

      Unless, of course, this finite mobile is a planet, which has already moved in an infinite local motion. This is allowed because its infinite motion is circular, and circular motion is recognized by physics as essentially different from motion in a straight line, which is how all terrestrial bodies move; and the planets must move with an infinite motion because they are the equivocal causes of generated species on earth… There’s so much falsehood here (though not unreasonable falsehood) it’s hard to know where to start.

      Here’s the fundamental problem: since A. admitted that motions that returned to themselves could be infinite (or even needed to be) he could only deny that “straight line” ones failed to do so by assuming that the space of Euclidean geometry was the same as real space, at least so far as a straight line in real space cannot return to itself. This is certainly a premise that would be granted to common experience, and it’s sturdy enough. But it’s not true nor necessary. In reality, it is just another dialectical postulate that was, like all things in natural science, open to revision. I’m not saying that it wasn’t a good theory in its time, but it no longer is.

  3. sancrucensis said,

    March 15, 2012 at 11:32 am

    “in turning to the Physics […] all one finds is a series of conclusions that are either false or of no value.”

    Which category does the demonstration of the first mover fall into?

    • March 15, 2012 at 11:52 am

      Well, we all agree it’s false as Aristotle actually gives it, sc. that there is a being who has moved the planets for an infinite amount of time (and who will continue to do so infinitely) on crystalline-sphere orbits (and these premises are integral to his proof!) but you probably mean the parts of the proof which are closer to common experience and which many argue are of permanent value. So lets deal with those: So far as the proof is based on the idea that mobiles cannot move without extended parts, it’s false and based on an unfruitful hypothesis. Again, so far as it’s based on the idea that nature is arranged in a hierarchy with equivocal causes on top, I’m leaning towards calling it false too. I see no such hierarchy in the universe nor do I see present cosmology as wanting because it does not have it. Man is not being caused by the sun and conserved by Saturn, and nothing replaced these sorts of causes (nor do they appear to be worth looking for.)

      I still think there is some form of the Prime Mover argument that works, but I don’t think that it can conclude from information provided by Natural science alone, or maybe (more modestly) from information that is proper to natural science. This opens up a great number of epistemological questions, but I’m not satisfied with either the Kantian answer or the abstractionist one.

      Even if I admitted the PM argument full stop, it seems to me that this is not a development proper to physics, and that the statement quoted is substantially true.

      • March 15, 2012 at 12:35 pm

        One last point: I think that the essence of natural science is to judge sensibles according to the information given to sense, and so I’d deny that there is any cosmological argument that belongs essentially to physics. My suspicion is that the natural world gives information to both sense an intellect by being itself neither sensible nor intellectual, but some substratum of both. Judgments belonging to physics must ultimately be made according to what belongs to the stream detected by sense, not the stream detected by intellect, though there is obviously some mingling of the two into a single object.

      • March 29, 2012 at 4:52 pm

        Man is not being caused by the sun and conserved by Saturn, and nothing replaced these sorts of causes (nor do they appear to be worth looking for.)

        Arguably, all life on earth is being conserved through the sun’s heat and light: green plants most clearly and all other animals through the necessity of a body temperature. But, even if the sun and planets are not “universal causes,” is such a conception absolutely essential to Aristotle’s cosmology? All I see in the Physics is a necessity of a first mover and some second mover which changes in relation to the cosmos as a whole: perhaps the first is God and the second the expansion of space. In fact, Aristotle’s conception of place justifies relativity to the extent that if there is no utterly immobile limit to be absolute place, no place has a perfectly absolute determination.

        If all motion is relative, and the relative must reduce to the absolute in some way, why not make the first motion growth? It seems clear enough that place is intimately bound up with quantity and so, if local motion cannot be the “first motion” why not the expansion of the quantity of the universe? That, at least, would give us Aristotle’s first moved mover again and, more importantly, would account for the findings of Lemaitre and Einstein.

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