Change and causality

Ed Feser has been defending his Aristotelianism against criticism from George Mason University physicist (and atheist) Robert Oerter, whose book on the standard model of particle physics I have just ordered second hand in hardback for £2 from the USA.  I've no idea if it's any good---these sorts of books are either too popular and convey none of the mathematics, or too advanced, and quite abstruse if you lack the background.  The Amazon and Google Books previews aren't very helpful, but the first chapter mentions Emmy Noether and doesn't dive straight into equations so I'm hopeful.  At less than £5 including p&p it's worth a pop.  I wonder when it will get here?

Oerter explains how contemporary physics remains silent as to when (and hence why) certain atomic level changes occur.  His example is the decay of an excited state of a hydrogen atom with the emission of a photon.  Radioactive decay of an atomic nucleus would be another.  The best that we can do is predict the mean lifetime of such states.  Physics says they decay 'spontaneously' though subject to certain statistical constraints.  Indeed, theory suggests that if there were physical properties that we are unaware of that do determine when such changes occur, so-called hidden variables, then the statistics that we see in experimental results would be different.  This is all very technical but it suggests to Oerter and many other physicists that our everyday ideas about causation do not extend down into the atomic world.  Ed Feser will have none of it. He clings to the metaphysical principle that

Any potential, if actualized, must be actualized by something already actual.

Or, in less technical language perhaps,

It is also sometimes formulated as the thesis that whatever is moved is moved by another or whatever is changed is changed by another.

So if an atom has the potential to transit from an excited state back to its ground state it would seem that this change, when it occurs, must be the result of some cause. 

But the status of causality as such is precisely what the principle of causality is about.  And that is why QM has nothing to tell us about the principle of causality.  They are simply not addressing the same question.  Given that you have already determined on independent grounds whether or not the principle of causality is true, QM may raise questions about how it is to be understood in contexts like that of the hydrogen atom (to allude to Oerter’s example). 

Am I alone in finding this a strange thing to say?  Feser doesn't tell us what these independent grounds for adopting the principle of causality might be.  They can't be empirical for the principle appears to be declared immune  to any countervailing evidence.  Rather, one can only guess that this principle is a straight jacket into which Feser has volunteered his thinking.  We simpy cannot view the world except through the lens of the principle of causality, he seems to be saying.  He goes on:

But there is nothing special about QM in that regard.  One billiard ball knocking into another, melting and freezing, electromagnetism, gravitational attraction, plant and animal growth, volitional behavior, divine creation, all involve very different sorts of efficient causality.  There are also distinctions to be drawn between essentially ordered and accidentally ordered causes, between causes that contain what is in their effects formally and those that contain what is in their effects only virtually, between total causes and partial causes, between the causality of substances and that of accidents, and so forth.  If you think that all efficient causality reduces to some crude, deterministic billiard-ball model, then QM might seem to be a challenge to the very notion of causality.  (“Look, there’s no little billiard ball deterministically pushing the electron into a higher energy level!  Causality itself crumbles!”)  But no Aristotelian or Scholastic would buy this simplistic conception of efficient causality in the first place.  (Naturalist critics of Aristotelian-Scholastic arguments rarely beg one question at a time.  They beg whole books full of questions.)

OK.  Aristotelian causation is a rich and sophisticated theory.  What does it have to say about why, on a realist perspective, an excited hydrogen atom decays to its ground state at a particular moment? Ed continues:

The principle of causality itself does not make any claim about how exactly efficient causes operate in all of these diverse cases.  It just tells us that whatever the details turn out to be, any potential will only be actualized by something already actual.  How does this work out in the case of QM? 

He then spends a paragraph or two explaining how it's not the laws of physics themselves that bring this about.  They do not even count as a formal cause.  They are not explanations at all, he says, but rather descriptions of 'how things will tend to operate given their natures, essences, or substantial forms'.  If there were to be a conflict between QM and the principle of causality then we should take an instrumentalist view of QM.  However,

An interpretation of QM that is both Aristotelian and realist will, naturally, insist that it is not the laws of QM themselves that cause anything, since they are mere abstractions from concrete systems operating in accordance with their substantial forms.  Hence it is in virtue of the substantial form of a hydrogen atom that it will behave in the manner described by QM, just as it is by virtue of the substantial forms of material things in general that they will exert a gravitational attraction on one another.   Now for the Aristotelian, the substantial form of an inanimate substance is not the efficient cause of its natural operations; rather, those operations flow “spontaneously” from it, precisely because it is in the nature of the substance to operate in those ways.  (See James Weisheipl’s Nature and Motion in the Middle Ages for an important treatment of the subject.)  Hence that a planet exerts a gravitational pull is just something it does by virtue of its nature or substantial form; it does not need a continuously operating efficient cause to make it exert such a pull.  That does not mean that there is in no sense an efficient cause of a thing’s natural operations, but that efficient cause is just that which gave the substance in question its substantial form in the first place, i.e. that which generated the substance or brought it into being.  It is not something that needs continuously to operate after the thing is brought into being.  Hence the efficient cause of a planet’s exerting a gravitational pull on other objects is just whatever natural processes brought that planet into existence millions of years ago, thereby giving it the nature or substantial form it has.  Its exerting that pull is now something it just does “spontaneously,” by virtue of its nature.  (Mind you, that does not mean that it can exist or operate even for a moment without a divine sustaining cause; it cannot do so, for reasons I spell out in my ACPQ article “Existential Inertia and the Five Ways.”  But that is a separate issue.  What I am talking about here is whether there needs to be some efficient cause alongside it within the natural order that causes it to exert a gravitational pull.)

Now, along the same lines, we might say that the hydrogen atom also behaves as it does “spontaneously,” simply by virtue of having the substantial form it does.  Why do the electron transitions occur in just the pattern they do?  Because that’s the sort of thing that happens in anything having the substantial form of a hydrogen atom, just as gravitational attraction is the sort of thing that naturally happens in anything having a substantial form of the sort typical of material objects.  What is the efficient cause of this pattern?  The efficient cause is whatever brought a particular hydrogen atom into existence, just as the efficient cause of gravitational attraction is whatever brought a particular material object into existence.  That is one way, anyway, of giving an Aristotelian interpretation of QM phenomena of the sort cited by Oerter, and it is intended only as a sketch made for purposes of illustration rather than a completely worked out account.  But it shows how QM can be naturally fitted into the Aristotelian framework using concepts that already exist within the latter.

Of course, critics of Aristotelianism will reject this way of interpreting what is going on.  Fine and dandy.  (Though please don’t waste everyone’s time with sophomoric Molière-style “dormitive virtue” objections to substantial forms.  I have explained why this objection is no good in The Last Superstition and Aquinas.)  The point is that QM itself gives one no reason whatsoever to reject it.  If the critics of the Aristotelian position are to find rational grounds for rejecting it, they must look elsewhere.

I have quoted Ed at some length for fear that if I paraphrase him I'll miss out something important.   Others must judge for themselves but I find this, as explanation, rather unsatisfying.   It comes down to what kind of answer I have come to expect for a why question.  Let's ignore the human and animal worlds for now because some why questions concerning people and animals we can answer with reference to intentions.  Let's concentrate on the vegetable and mineral.  Many why questions concerning change in an object or system are nicely answered by reference to the how of its parts.  If we're allowed a certain metaphysical freedom in interpreting 'system' and 'part' then perhaps all such questions can be answered in this way.  By 'the how of the parts' I mean description of the parts and their interactions, seen as instances of familiar kinds.  The hands of a pendulum clock turn at a seemingly steady rate because falling weights turn the interlocking gear wheels and the regular swing of the pendulum driving the escapement allows this to happen in periodic discrete equal tiny steps.  A plant grows because its cells multiply and themselves grow.  Rain falls because water from the seas evaporates, the vapour rises, and subsequently condenses.  Explanation in the biological and physical sciences follows this paradigm closely:  the why of plant growth is the how of cells; the why of cells is the how of molecules; the why of molecules is the how of atoms; the why of atoms is the how of particles and fields.  And there the explanations stop.  Perhaps the why of particles and fields is the how of certain abstract mathematical entities, but here we seem to be taking a step into a different metaphysical domain.  Let's stay within the physical, as we currently conceive it.  A general characteristic of the explanatory chain is that as we proceed the number of entities increases but the number of kinds falls.  The explanations become more and more general, less and less 'ad hoc'.  This universality I find deeply satisfying.  Perhaps it fills the same need in me that in others is filled by God.   But contrast this with Ed's Aristotelianism.  Everywhere we look we find substantial forms, doing their thing.  What relates the form of a plant to the form of its cells, and the form of its cells to the form of its molecules?  If everything is a combination of undifferentiated prime matter and form, where is the Aristotelian science of forms which would reveal the unity of the world?  It simply doesn't exist. And it doesn't exist because there is no need of it.  Every form is complete unto itself like a Leibnizian monad.  And there are myriads of varieties.  I won't stoop to complaints about 'dormitive virtues'.  I will simply say that, to my mind, the whole gallimaufry utterly lacks explanatory power.  As an over-arching conception of the world it adds nothing to what I can see for myself.  Is this a rational ground for rejecting it?   Would it be a rational act to adopt a metaphysic that failed to satisfy a hunger for understanding?  I think not.  But in any case, look elsewhere I shall.