Time for the two-week teaching sojourn.
In order to grasp cause, we need a brief, a very brief, introduction to the Aristotelian metaphysics of change. These are ancient views, largely abandoned in moderns, but becoming current one again. Philosophers like Nancy Cartwright, Ed Feser, and others are restoring a full philosophy of causation back to the sciences. This is a précis of Feser’s Scholastic Metaphysics. Full arguments are not given here; interested readers should follow up with the authors mentioned.
Contingent things exist as composites of act and potency, or actuality and potentiality. A lump of clay is potentially a vase. A lump of clay is not potentially a 1965 Barracuda with a 278 (a weepingly beautiful automobile) nor is it potentially a stereo. A vase is in potentia to being a pile of shards. A vase is in actuality a vase, and a lump of clay is in actuality a lump of clay. The reader is in potentia to receiving a salary of fifty-thousand a year, unless he already possess that trait, and is therefore in actuality receiving it. And so on.
Some thing or things must cause every potentiality to be an actuality, must cause every change. A potter, say, is required to turn the potential vase in a lump of clay into a vase, while a child can actualize the shards which are in potentia in that vase. Feser (p.33) : “These potentialities or potencies are real features…even if they are not actualities.” Potentialities exist. The number of numbers between 0 and 1 is potentially infinite, but not actually infinite in practice, a fact which has special consequences in measurement.
Whatever is changed, is changed by another: whatever is in potential, is made actual only by something actual. Whatever cannot be changed, is not changed. (Don’t skip that sentence.) It is not the lump’s potential to be a vase that turns it in into a vase, it is an actual potter. The potter uses his power of making a vase; his hands are the efficient cause. Clearly, the potter has the power to make the vase even when he is not making it (say, when he’s taking his Barracuda out for a spin). Aquinas said “nothing can be reduced from potentiality to actuality, except by something in a state of actuality” (Summa Theologiae I.2.3; quoted in Feser). This is the principle of causality which I take as axiomatic and necessary to do any science. Things do not happen without causes.
Science deals with the contingent: (p. 106) a “contingent thing is such that its existence is distinct from its essence, where its essence is in potency relative to its existence, which actualizes it…To cause a contingent thing is thus to actualize a potency…whatever is contingent has a cause…” which is everything in science. This is not to say that everything has a cause; only that contingent things do.
A child throws a ball and it hits the vase. As the ball hits, the vase buckles; as the ball hits, the vase begins to break. The “event” is the ball-hitting-vase, and it is simultaneous, which is not to say instantaneous. The ball hitting and the vase buckling happen through a short period of time; they are not different events “entirely loose and separate”, to use Hume’s mistaken phrase. It is not because we “happen” to see, or “chance” upon the spectacle of ball-hitting-vase that we know the ball caused the vase to break. It is because we learn, via induction, that balls traveling at sufficient speed have the power to break vases of this certain type. It is the vase’s nature to break when hit by balls like that under these circumstances. We are back to essence. Understanding essence and powers is to understand cause.
Many modern authors put this the wrong way, saying first the ball hits then the vase breaks. This is not so. There are not two separate events, but one joint event, spread through time. This point is crucial. It is difficult to find modern examples where distinctness in events and separateness in time is not assumed. The mistake leads to some curious views indeed. An example is in Roberto Mangabeira Unger and Lee Smolin’s The Singular Universe and the Reality of Time: A Proposal in Natural Philosophy which proposes the “laws” of nature change through time, but which leaves out what these causes are.
Of course, that the ball-hitting-vase is spread through time, however brief, does not mean that all events are. Certain quantum mechanical events are thought to be instantaneous. But that merely confirms the view that we are not witnessing “loose and separate” events, but joint ones.
Knowing the ball was the efficient cause of the vase breaking is not the whole story, though it is enough for most (it was for my mother). There are all sorts of forces involved, including the ball’s momentum, friction, elasticity of both objects, and so forth. These are not necessary to understand to say the ball caused the break. These additional forces can be investigated to form a deeper understanding of the precise mechanisms. Each of these investigations are no different in spirit than the gross (my mother’s) version. The essence and powers of the forces involved are understood to be causes. But there are limits.
Let’s investigate the joint event more closely. The ball and vase are not monoliths, but composed of smaller parts. As the ball pushes into the vase, the molecules of the ball and vase are themselves undergoing change. These changes, which are actualizations of potentials, are caused by something actual, which are the atoms in the molecules. These are also undergoing change, which are again actualizations of potentials, and are also caused by something actual. This might be the interactions of the constituents of the atoms, the electrons, protons, and nuetrons, which are also undergoing change. More actualizations of potentials caused by other somethings which are actual. These may be quarks, which are themselves pushed about by (say) actual strings (or super-strings or God knows what), which themselves, perhaps, are caused to change by something below those. All of this is happening here-and-now, simultaneously, but again not necessarily instantaneously. This is called a per se times series, or a per se series of events in the here-and-now time.
But you can see that this process cannot continue to infinity. It must bottom out, or nothing can ever get moving; no changes could ever be made. There must be some “first cause” or “first mover” or “changer”. This first cause must be entirely actual and have no potential. It is what makes all “bottom” potentialities actual. It is responsible for every contingent event, at base. This is the prime or primary cause, which is ever-present. Science is and must forever be ignorant of this cause. It is a handy explanation of quantum mechanical EPR-like events, or whatever is “beneath” them.
All of the other here-and-now causes—string into quark into protons into etc.—are secondary causes. All have powers and essences, and it is the goal of science to understand these.
There is another type of causal series, this one distinct in time, an accidental series. The classic, and really perfect, example is that a grandfather caused his son to be made and he, your father, caused you to be made. This doesn’t stop with your grandfather, naturally, but continues along a string into the past. Remove one of the knots in the string, i.e. remove one of the causes, and you would not be reading this now.
Unfortunately, in practice, data analysts often compile accidental series as if they were causal. Example: yearly (or monthly or daily) average temperature (or sales figures, etc.). Last year’s average did not and could not cause this year’s average. Results? Misascribed causes and wild over-certainty. I leave discussion of these accidents until later.