An article was recently published online in the International Journal for Philosophy of Religion by Thomas Oberle titled “Grounding, Infinite Regress, and the Thomistic Cosmological Argument.” Oberle criticizes Aquinas’ argument against infinite regress as question begging.
Oberle recognizes the distinction between essentially and accidentally ordered causal series, and with it the difference between derived and underived causal power. He maintains, however, that the Thomistic argument fails because it equates a finite essentially ordered causal series without a first, underived cause (such as a few boxcars connected to a caboose) and an infinite essentially ordered causal series without a first, underived cause. The former is clearly impossible because it would involve the existence of a cause whose causal power was neither underived nor derived; the cause at the head of the series does not have derived causal power because there is no prior cause to derive it from. An infinite essentially ordered series, however, involves no such absurdity, for every cause has a prior cause from which it derives its causal power, and so there is no cause without at least derived causal power. How do we know that there cannot be an infinite series of borrowers with no owner, Oberle asks?
But despite acknowledging the distinction between essentially ordered and accidentally ordered causal series, Oberle fails to fully appreciate the nature of essentially ordered series. His reasoning implies that having derived causal power renders a secondary cause a sufficient cause of the effect in question, whereas the kind of causal subordination of which Thomists speak means that the secondary cause is not a sufficient cause of the effect. The secondary cause is a conduit for causality; without a first cause with underived causal power, there is no cause of the effect.
Perhaps the example of the train and the related example of a man who moves a stone with a stick could mislead here. If the boxcar and the stick had the requisite kinetic energy, whether they got it from somewhere else or not, they could move the caboose and the stone by themselves. (Although to move the stick or the caboose uniformly, as in the examples, they would have to have a store of potential energy and the ability to convert it themselves, so as to maintain a constant velocity in the resisting caboose and stone; in other words, they would have to be something like engines.) The example of links in a chain holding up an engine block better illustrates Aquinas’ notion of an essentially ordered series. The link attached to the engine block simply does not hold up the engine block, even though it has derived causal power to do so. Neither does the link above it. Only the hoist holds up the engine block, for only there does one find the causal power to do so. If there were no hoist, but only an infinite series of links in a literal chain, the whole chain and the engine block would fall.
Hence infinite essentially ordered causal series are impossible. Without a first cause there is no causality at all, whether derived or underived. Given the nature of derivative causal power in an essentially ordered series, there is no derived causal power without an underived causal power. Derived causal power is derived not from the immediately prior cause in the series, but only from an underived causal power that can terminate the series.