Aristotle’s Revenge 1: on the philosophy of science

This is part 1 of a three part series on Scholasticism and some topics in the philosophy of science, loosely organized around a review of Edward Feser’s new book Aristotle’s Revenge:  The Metaphysical Foundations of Physical and Biological Science.

Importance of a philosophy of nature

There is an impression in some quarters that scholastic philosophers and theologians are always stepping on scientists’ toes, trying to shut down investigation of empirical questions with sophistical a priori arguments. I think if anything, scholasticism’s failing has more often been the opposite–a great retreat into metaphysics, into principles that, being supposedly valid in any possible universe, can tell us nothing about the one that happens to exist. While this does protect against “Galileo affairs”, there is the danger that we will not know how to apply the general categories of “substance”, “potency”, etc. to the world we experience and have revealed to us in science. And concepts we cannot apply, we don’t really understand.

The other danger is that, without a thought-out metaphysics as guide, we may read into scientific theories an unexamined metaphysics and recapitulate ancient fallacies. Science is the fullest and most systematic exposition of our experienced world. We do want to read our ontology out of it, but how to do this is neither obvious nor easy, and we need the help of general metaphysics.

Thus, the American Thomist Edward Feser’s philosophy of science book, Aristotle’s Revenge, is to be welcomed, whether or not one agrees with his conclusions.

Transcendent Laws vs. Causal Potencies

Why think that Aristotle would be a useful guide for reading ontology out of science? I became convinced of it when I noticed that people, scientists and nonscientists alike, mean two different things when they say that the laws of physics explain such-and-such. One view, the sensible one I would say, is that laws of physics are descriptions of how the sorts of things that happen to exist behave. But I have noticed that sometimes laws of physics are treated as universe-transcending causal agents, as for example when they are said to enable the universe itself to come into existence out of “nothing” (another grievously misused word). This is in fact the error of Plato, who also put the loci of intelligibility in a transcendent realm, and physical laws conceived this way face all of the same interaction problems. Aristotle solved the problem in the only way possible, by relocating the forms into the physical world, and we must do the analogous thing with physical laws.

Feser explains this pretty well in his previous book Scholastic Metaphysics by retrieving the concept of potency. He notes that contemporary analytic philosophers have themselves reinvented the concept under the name “physical intentionality”, and Feser argues pretty convincingly that it can’t be reduced to actual structure if one is unwilling to appeal to transcendent laws of nature.

Suppose A is potentially X but actually Y. A is not actually X, but A being X is more than a counterfactual statement:  counterfactuals are statements; potencies are the beings that ground such statements.  Let’s apply this to my problem. Consider a system in classical mechanics. Its actual state is a point surrounded, one might say, by a phase space of possibilities. The phase space contains structure (a symplectic 2-form, a Hamiltonian) which, to do their work, must be defined in the nonactual space. (They would be senseless if only defined at the actuated point.) The Aristotelian solution is to assign a sort of reality (potential being) to unoccupied state space to represent the nature of the system and to be where the “laws of physics” live.

Naive attempts to read ontology out of science often end in metaphysical extravagance. Other examples of this come from attempts to relegate features of the manifest world exclusively to the mind. Early modern discourse on “secondary qualities”, when it was falsely believed that physics does not recognize the reality of color, heat, and other non-geometric qualities, is a case of this. So too are claims that intentionality and teleology exist only in the mind. The trouble with this is that if the mind contains things not in the material world, then minds must be mysterious, immaterial things.

I support the modern prejudice that philosophy should not need to posit immaterial metaphysical constructs–Platonic forms or immaterial souls, regardless of whatever names these hide under–to explain the material world. The claim I shall investigate is that Aristotelianism-Thomism is materialism done right.

Images scientific, manifest, and metaphysical

Feser endorses structural realism in a general way, without accepting any narrow version of this position that reduces scientific knowledge to triviality. One suspects that with this label Feser mostly means to endorse my starting points above: science gives us real knowledge about the world, but ontology can’t just be read off its surface. In Feser’s case, there is also a strong emphasis on the supposed incompleteness of physics, or of scientific reductionism more generally.

I would like to clarify the assertion that physics gives an incomplete picture of the world, because many philosophers make such claims, but they can mean very different things. I will concentrate on the possibility that physics misses information about the material world, granting as obvious that physics has little to say about things like ethics and religion that are beyond its purview. The most modest and popular antireductionist claims are of the “missing the forest for the trees” variety. Even if one could predict the behavior of machines, people, and animals by evolving all of their molecules, one would miss out on the macroscopic categories (function, motivation, etc) that provide a distinct layer of intelligibility at this level. Thus, philosophers speak of irreducibly new phenomena emerging from the lower level. It’s not clear, though, that any reductionist would disagree. Some of Feser’s arguments are of this kind, e.g. that to explain themodynamic or macroscopic chemical phenomena, the explanation must refer to those phenomena and thus be cognizant of the macrolevel. This is true, but it takes one no farther than forest/trees anti-reductionism (i.e. emergentism).

A more radical claim would be that the laws of physics are actually wrong and don’t apply outside of the highly controlled situations in which scientists test them. This is Nancy Cartwright’s position, but her examples are unconvincing. Feser flirts with this idea, but the main thrust of his argument is that physics is incomplete because it is an abstraction of reality, and abstractions necessarily leave things out. No doubt, physicists routinely discard “irrelevant” details in their explanations, but the claim that physics necessarily leaves out information about the physical world is a radical one.

It does nothing against Feser’s claim to point to the astounding reliability of physics, because physics could be perfectly reliable in its own order while completely ignoring features outside this order. However, if claims of the limitations of physics are to be more than gestures of epistemic humility, we must have some independent source of information.  Feser sometimes thinks he can get this from our manifest image “common sense” experience/conceptualization of the world, but I find this questionable.

For example, in a section on secondary qualities, Feser rightly objects to claims that color is a mere subjective experience. Physics has clearly established that color is the wavelength of visible electromagnetic waves. But Feser dismisses this account of color as not being “color as common sense understands it”, so that the world of physics is still in some esoteric way colorless. I do not understand this at all. Common sense is not an understanding of light rival to that of optics; it’s not an understanding at all, but a bare experience of it. The qualia of colors (the only thing physics clearly does not provide) have no independent structure, which allows us to identify them simply as the experience of light at different wavelengths. The color of physics, meanwhile, explains all our experiences of color: the blueness of the sky, the order of colors in the rainbow, the red glow of a hot stove… What else is there?

Feser also does not believe that physics captures the reality of change and temporal succession. Again, the claim will seem odd at first, since in physics we often encounter cases of \frac{d}{dt}something\ne 0. Is that not change? Feser replies that physics ignores the difference between space and time, that it only recognizes “static change”, which fails to capture time “as common sense understands it”. Here I would partly agree and partly disagree.  It is not true that temporal succession is no different in physics than spatial adjacency. Spacetime has a definite causal structure, encoded in the metric, so that one can unambiguously say whether two events are timelike separated and hence that one could influence the other.  Only spacelike hypersurfaces are Cauchy surfaces.  Nor is a moving object at an instant of time static: it is perfectly sensible to have \frac{d\vec{x}}{dt}\ne 0 even though dx\rightarrow 0 as dt\rightarrow 0.  (If you find something metaphysically suspicious about limits, re-express in terms of the tangent space at a point.)

On the other hand, the situation of time is in some ways opposite to that of color. The aspects of “manifest time”–spatially separate simultaneity, “flow” from the past to the future–are not direct experiences but a sort of first-order conceptualization. I will later argue that physics’ conceptualization is superior in adequacy to experience, parsimony, and internal coherence. For now, I’ll just point out that pointing to the experience of change does no damage to the physicist’s spacetime picture, because that I have different experiences at different events on my worldline is expected on the physicists’ picture too.


Having registered this single (but important) epistemological disagreement with Prof. Feser at the beginning, I will continue with his and my exploration of an Aristotelian reading of the world revealed to us by science. In part 2, we’ll look at the ontology of space, time, and motion.  In part 3, we’ll turn to mereology: the interpretation of quantum mechanics, the Aristotelian critique of atomism, and the reality of biological function.

10 thoughts on “Aristotle’s Revenge 1: on the philosophy of science

  1. Thank you for this. I bought the book recently and it has been serving admirably as a dust collector but I have begun to suspect the contents may have some other value.

  2. Pingback: Aristotle’s Revenge 1: on the philosophy of science | Reaction Times

  3. Thanks for this review.

    Physics has clearly established that color is the wavelength of visible electromagnetic waves. But Feser dismisses this account of color as not being “color as common sense understands it”, so that the world of physics is still in some esoteric way colorless. I do not understand this at all. Common sense is not an understanding of light rival to that of optics; it’s not an understanding at all, but a bare experience of it. The qualia of colors (the only thing physics clearly does not provide) have no independent structure, which allows us to identify them simply as the experience of light at different wavelengths. The color of physics, meanwhile, explains all our experiences of color: the blueness of the sky, the order of colors in the rainbow, the red glow of a hot stove… What else is there?

    I’m not sure I understand what your objection is. Even if qualia have no independent structure (I agree), isn’t the fact that qualia – the subjective experiences – are something that physics cannot give us precisely the point? What do you think of thought experiments like Mary’s Room or Nagel’s “What is It Like to Be a Bat?”
    If there were nothing left to explain, then why the drive among naturalists to explain consciousness completely in terms of neuro-structure (or whatever)? Isn’t the seemingly irreducible first-person point of view inherent to qualia exactly what modern materialists find problematic?

    • Well, I would say that if we’re just talking about experience, then this would seem to be a truth about us, rather than a truth about light.

      I agree with Feser, though, that primary vs. secondary qualities is not a fruitful way of thinking about this. After all, there are, I suppose, qualia associated with perceptions of spatial extension, so I don’t see any way of claiming that experience of the directions photons are moving when they hit one’s eye (the basis of the experience of direction/space) is more real than our register of the energy of those photons.

  4. I am feeling my way towards something like this, but I don’t think I can accept the whole system yet. But I was figuring out these parts:
    – It is not true that only matter exists. Information also exists. Information is a weird thing. It can take any material form. “4” made of pixels on the computer screen and “IV” drawn in sand still mean the same information. Information is meaning. It requires conscious minds. However, my usual problem is this: I don’t know if our minds make up, create information or just notice it.
    This is part of a bigger problem. I think there are two large epistemologies out there, for want of a better term we could call them creative vs. perceptive. Aristoteleans, Christians, tend to think truth is out there and we are just perceiving it. The modern model is creative, you MAKE a logical model of things in your mind and test it empirically. The model is like a machine. And the model is only perfect if its moving parts are the same as of the same machine – causality – in reality. This argues for the perceptive model. Sir Roger Penrose wrote in The Emperor’s New Mind that mathemathics looks like a creative, inventive process and yet it tends to feel like a discovery. You just spot it at some point. And complex numbers were invented for a specific purpose yet we keep discovering new and new things about them. Which would imply they somehow exist out there and we are just perceiving, discovering them. These are strong arguments. Still, the perceptive model just seems so *weird* !
    – Aristotle: mixing matter with form. Well, that sounds like what a 3D printer is actually doing. Mixing matter in a basic blob form with information in the computer.
    – Aristotle is saying form always appears mixed with matter, and it is only in your mind (and perhaps Gods) you get pure form. We get the forms by abstracting away the similarities of various things. This actually sounds like what we are really doing. But are we creatively abstracting them away or perceptively noticing their abstract forms?
    I was musing about this here:
    “I think Feser and the Scholastics also believe in higher levels of immateriality, which are really like ghosts, but that is not really relevant. But to be fair I am not even sure about that, really. After all they believe in the resurrection of bodies after the last judgement because they are aware humans do not have the kind of ghosts that could live a happy ghost life in an afterlife. Because only the abstract-thinking aspect of the human mind is immaterial. Our emotions and all that not. That’s brain stuff. But Aquinas even argued angels are pure form and could that really mean angels are like software code?
    But saying software is immaterial and you need that for your computer to do something useful is obvious and correct. After all if software was not immaterial, we could not even try to argue that videogame piracy is not theft 🙂”

    • So the form of a plant would be its DNA. “That which makes it what it is.” Mixing DNA with matter you get a tree. With animals it is a bit more complex. A trained dog is different from am untrained dog. So the information in the brain is also part of the form…
      I think hylomorphism dualism does make sense because information is really a different thing than matter. But it is hard to grapple with it in the original terminology…

  5. Hi, Bonald: it seems like color is a wavelength of light in the same way “love” is endorphins. Those physical things might be implicated in the production of the phenomena but neither one can be reduced to their physical antecedents.

    From one point of view what really exists is the spectrum of light; from the very fast and short wavelengths, to the relatively slow and long wave lengths.

    The only reason we break up the spectrum into what we call “colors” is because of the effect of certain wavelengths have on our organs of perception and brains. We call a portion of the spectrum of light “green” because of what it looks like subjectively. We only know that that portion of the light spectrum is “green” by looking at it. Without subjective experience there would be no grounds for distinguishing one “color” from another because “color” would not exist as far as we knew.

    Light waves are a necessary but not sufficient condition for the experience of color. If we were all color blind, like some animals, then we would never talk of color but only of wave lengths of light. And we would have no means of breaking the light spectrum into bits.

    A wavelength of light can give rise to the phenomenon called “color” but color cannot be reduced to its physical correlate. A scientist could tell us that this wavelength of light is faster or slower than another, but without subjective experience, he could not tell us that this wavelength of light has gone from being a shade of the color “green” to some other color.

    I have sometimes toyed with the idea of color realism. In that case color is a fundamental ontological reality and our organs of perception simply allow us to perceive it. The nonrealist position would be that what we call “color” is simply the name we give to the effects of wavelengths of light on our nervous system. Similarly, “sound” is not sound waves. Sound waves are merely potential sound. Without ears to hear it, sound does not exist. Certainly the world of a deaf person contains no sound. If ears did not exist at all, we would not refer to sound waves by that name, but only as vibrations transmitted through a medium like air or water. Again, sound realism is a fun idea to me – though I’m not sure if sound should have an absolute existence independent of animal hearing or whether it requires God to hear it.

    • Hello Dr. Cocks,

      Is our disagreement one over definition, that you mean by color a subjective experience and I mean by it the objective reality that is experienced (and which could equally well be distinguished by the colorblind using prisms, diffraction gratings, the photoelectric effect, color filters, etc)? So, for instance, what you call green is the experience in a being like us of what I call green.

      In this case, it’s not clear that we have achieved disagreement, although I’d be more inclined to swap the designations of “realist” and “anti-realist”. By saying that, for example, green just is EM waves in the wavelength range 520-560nm, and our experience of green just is the experience of such radiation, I fend off worries that color has a reality inaccessible to our experience or to physics.

      Suppose someone out there has the experience that we call red when he sees grass. Of course, he would have learned to call that experience one of seeing “green”. By my definition, which is public, he would indeed be seeing green. Possibilities like this do raise the possibility that physics ignores something not about color but about us. It’s considerations like this that make me lean toward property dualism.

  6. Pingback: Materialism done right: my review of Aristotle’s Revenge in one post | Throne and Altar


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