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 something. 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 even though as . (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.