Essentially Ordered Causal Series
| Principal locus | Summa theologiae I, q. 2, a. 3; q. 46, a. 2 ad 7 |
|---|---|
| Definition | A causal series in which intermediate causes exercise their present causality only in virtue of a prior cause |
| School | Thomism |
| Branch | Thomistic philosophy |
| Status | Thomistic metaphysical distinction |
An essentially ordered causal series, traditionally called a per se ordered or hierarchical series, is an order in which intermediate causes exercise causal power here and now only in virtue of a prior cause. The paradigmatic image is a hand moving a stick that moves a stone: the instrument has real causal efficacy, but its instrumental action is derivative while it acts. Aquinas uses this structure in arguments from motion and efficient causality. The essential order concerns dependence in causing, not merely the dates at which the members happen to exist.[1][2]
Causal dependence in the present
A series is essentially ordered when a middle member causes only as an instrumental or subordinate cause whose present causal efficacy is received. The stick moves the stone only while moved by the hand; a hand may act through muscles and nerves, which in turn presuppose living powers. The point is not that the instrument is unreal. The stick truly moves the stone. Its very mode of causing, however, refers beyond itself to a principal source from which its instrumental action derives.[3][4]
Essential order is therefore an explanatory relation, not a list arranged merely by clock time. Members may operate simultaneously in familiar examples, which makes the dependence vivid, but simultaneity alone does not define the series. The decisive question is whether an intermediate cause has the relevant causal power independently in the order being considered. If its action as cause is borrowed or applied here and now, removing every non-derivative source would remove the causal activity of the entire subordinate order.
Why an infinite regress fails
Aquinas argues that an essentially ordered series cannot regress without a first member. Intermediate causes cause only through the causal influence they receive. Adding infinitely many derivative instruments does not supply an underived source of the influence: an endless series of sticks, none moved otherwise, would not move a stone. The denial is not the crude claim that an actual infinite cannot be imagined or numbered. It concerns a hierarchy in which every member's relevant causal contribution is essentially dependent.[1][2]
The word first denotes priority in the causal order, not necessarily the earliest event on a timeline. The principal cause need not be one more body standing at the far end of a very long chain. In Aquinas's natural theology, reasoning from derivative actualization or efficient causality terminates in a source that is not itself actualized or caused in the relevant way. God is thus not inserted as the oldest member of the same class but identified as transcendent first cause.[1][2]
The First and Second Ways
The First Way begins from change: whatever is being reduced from potency to act is actualized by something actual, and ordered movers cannot all be merely moved instruments. The Second Way begins from the order of efficient causes and denies that a thing can be the efficient cause of itself. In each case the conclusion depends upon the causal order, not upon the slogan that everything has a cause. Aquinas explicitly exempts the first cause from the dependent mode that prompts the regress.[1]
These concise arguments require the surrounding metaphysics of act and potency, instrumental causality, and essentially ordered dependence. Treating them as assertions about an earliest observable event weakens them. The immediate datum is present change and present causal activity. Even if a physical sequence had no first temporal event, Aquinas asks what accounts for its actualization and causal power now. The answer he seeks is first in ontological dependence, whether or not it is first in measured time.[2]
Not the same as a temporal beginning
Aquinas held by faith that the world was created with a temporal beginning, but he denied that philosophy could demonstrate that beginning. He therefore distinguishes the impossibility of an infinite regress among essentially ordered causes from the disputed possibility of an infinite accidental succession. The distinction blocks a common anachronism: his arguments for a first cause do not secretly assume that the universe began a finite number of years ago. Creation also means radical dependence upon God, not only the first instant of cosmic history.[5]
For the same reason, scientific accounts of early cosmic states neither establish nor overthrow an essentially ordered causal argument by themselves. Cosmology studies physical conditions and temporal development. Metaphysics asks about the actualization, existence, and derivative causal power presupposed by any physical state. The disciplines can inform one another, but their questions are not interchangeable. A gap in present cosmology is not a premise of Aquinas's argument, and a complete physical model would not abolish first causality.
Terminology and careful use
The expressions essentially ordered and per se ordered are later standard translations of distinctions Aquinas states through several examples and formulations. Hierarchical series is a useful modern synonym when it does not suggest an ecclesiastical rank. By contrast, a linear or accidentally ordered series concerns succession in which a later cause possesses its causal power after an earlier cause has ceased. Father, son, and grandson illustrate that different relation more clearly than hand, instrument, and object.[5][3]
An analysis must specify the causal respect at issue. The same things can belong to different series under different descriptions. A carpenter is the principal cause of a table through tools; those tools may themselves have been manufactured in a historical succession that is accidental to the present act of carpentry. Thomistic arguments succeed only when the claimed derivative power and its hierarchy are shown, rather than inferred from the mere fact that several events can be arranged in a sequence.[3]
References
- Back to citation occurrence 1.0 Back to citation occurrence 1.1 Back to citation occurrence 1.2 Back to citation occurrence 1.3 Thomas Aquinas, Summa theologiae I, question 2, article 3 — The First and Second Ways from ordered movers and efficient causes to a first mover and first efficient cause.
- Back to citation occurrence 2.0 Back to citation occurrence 2.1 Back to citation occurrence 2.2 Back to citation occurrence 2.3 Thomas Aquinas, Summa contra Gentiles I, chapter 13 — Arguments from ordered moved movers to a first unmoved mover, with the causal priority required by instrumental movers.
- Back to citation occurrence 3.0 Back to citation occurrence 3.1 Back to citation occurrence 3.2 Thomas Aquinas, Summa theologiae I, question 7, article 4 — The contrast between an essential order of carpenter, hand, and hammer and an accidental succession of hammers.
- Back to citation Thomas Aquinas, Summa theologiae I, question 105, article 5 — God's operation in every agent as first cause without denying the genuine operations proper to created secondary causes.
- Back to citation occurrence 5.0 Back to citation occurrence 5.1 Thomas Aquinas, Summa theologiae I, question 46, article 2, reply to objection 7 — The distinction between essentially and accidentally ordered efficient causes and Aquinas's denial that reason demonstrates a temporal beginning of the world.