98. Some Scholia on Causation. the Principle Of Causality.—Before enumerating the principal kinds of efficient cause, and analysing the nature of efficient causality, we may set down here certain self-evident axioms and aphorisms concerning causation in general. (a) The most important of these is the Principle of Causality, which has been enunciated in a variety of ways: Whatever happens has a cause; Whatever begins to be has a cause; Whatever is contingent has a cause; Nothing occurs without a cause. Not everything that begins to be has necessarily a material cause, or a formal cause, really distinct from itself. For instance, simple spiritual beings, like the human soul, have no material cause, nor any formal cause or constitutive principle distinct from their essence. Similarly, the whole universe, having been created ex nihilo, had no pre-existing material cause. All the material beings, however, which are produced, generated, brought into actual existence in the course of the incessant changes which characterize the physical universe, have both material and [pg 370] formal causes. But the Principle of Causality refers mainly to extrinsic causes. It is commonly understood only of efficient causes; and only in regard to these is it self-evident. We shall see that as a matter of fact nothing happens without a final cause: that intelligent purpose pervades reality through and through. This, however, is a conclusion, not a principle. What is really a self-evident, axiomatic, necessary principle is that whatever happens has an efficient cause. Only the Necessary, Self-Existing, Eternal Being, has the sufficient reason of His actual existence in Himself, in His own essence. That any being which is contingent could exist independently of some other actual being as the cause of this existence; that it could have come into existence or begun to exist from absolute nothingness, or be produced or brought into actual existence without any actual being to produce it; or that, once existing and subject to change, it could undergo change and have its potentialities actualized without any actual being to cause such change ([10])—all this is positively unthinkable and absolutely repugnant to our intelligence; all this our reason peremptorily declares to be intrinsically impossible. Nor is there question of a mere psychological inconceivability, such as might be due to a long-continued custom of associating the idea of a “beginning” with the idea of a “cause” of this beginning—as phenomenists generally contend.[453] There is question of an impossibility which our reason categorically dictates to be a real, ontological impossibility. The Principle of Causality is therefore a necessary, a priori, self-evident principle.
(b) Every effect must have an adequate efficient cause, i.e. a [pg 371] cause sufficiently perfect, sufficiently high on the scale of being, to have the active power to produce the effect in question; otherwise the effect would be partially uncaused, which is impossible.
(c) An effect cannot as such be actually more perfect than its adequate (created) cause. The reason is that the effect as such is really dependent for its actuality on its adequate created cause. It derives its actuality from the latter. Now it is inconceivable that an agent could be the active, productive principle of a greater perfection, a higher grade of actuality, than itself possesses. Whatever be the nature of efficient causality, actio and passio ([102]), or of the dependence of the produced actuality upon the active power of its adequate efficient cause ([10]), the reality of this dependence forbids us to think that in the natural order of efficient causation a higher grade of reality can be actualized than the agent is capable of actualizing, or that the agent can naturally actualize a higher or more perfect grade of reality than is actually its own. We must, however, bear in mind that there is question of the adequate created cause of an effect; and that to account fully for the actualization of any potential reality whatsoever we are forced to recognize in all causation of created efficient causes the concursus of the First Cause.
(d) The actuality of the effect is in its adequate created cause or causes, not actually and formally, but potentially or virtually. If the cause produce an effect of the same kind as itself (causa univoca), as when living organisms propagate their species, the perfection of the effect is said to be in the cause equivalently (aequivalenter); if it produce an effect of a different kind from itself (causa analoga), as when a sculptor makes a statue, the perfection of the effect is said to be in the cause eminently (eminenter).
(e) Omne agens agit inquantum est in actu. The operative power of a being is in proportion to its own actual perfection: the higher an agent is on the scale of reality, or in other words the more perfect its grade of being, the higher and more perfect will be the effects achieved by the exercise of its operative powers. In fact our chief test of the perfection of any nature is [pg 372] analysis of its operations. Hence the maxim so often referred to already:—
(f) Operari sequitur esse; qualis est operatio talis est natura; modus operandi sequitur modum essendi. Operation is the key to nature; we know what any thing is by what it does.
(g) Nihil agit ultra suam speciem; or, again, Omne agens agit simile sibi. These are inductive generalizations gathered from experience, and have reference to the natural operation of agents, especially in the organic world. Living organisms reproduce only their own kind. Moreover, every agency in the universe has operative powers of a definite kind; acting according to its nature it produces certain effects and these only; others it cannot produce: this is, in the natural order of things, and with the natural concursus of the First Cause. But created causes have a passive obediential capacity (potentia obedientialis) whereby their nature can be so elevated by the First Cause that they can produce, with His special, supernatural concursus, effects of an entirely higher order than those within the ambit of their natural powers.[454]
(h) From a known effect, of whatsoever kind, we can argue with certainty, a posteriori, to the existence of an adequate efficient cause, and to some knowledge of the nature of such a cause.[455] By virtue of the principle of causality we can infer the existence of an adequate cause containing either equivalently or eminently all the perfections of the effect in question.
99. Classification of Efficient Causes.—(a) We have already referred to the distinction between the First Cause and Second or Created Causes. The former is absolutely independent of all other beings both as to His power and as to the exercise of this power. The latter are dependent, for both, upon the former.
The distinction between a first, or primary, or independent cause, and second, or subordinate, or dependent causes can be understood not only of causes universally, but also as obtaining among created causes themselves. In general the subordination of a cause to a superior or anterior cause may be either essential or accidental: essential, when the second cause depends—either for its existence or for an indispensable complement of its [pg 373] efficiency—on the present actual influence of the other cause; accidental when the second cause has indeed received its existence or efficiency from this other cause, but is now no longer dependent, for its existence or action, on the latter. Thus, living organisms are, as causes, accidentally subordinate to their parent organisms: they derived their existence from the latter, but are independent of these when in their maturity they continue to exist, and live, and act of themselves and for themselves. But all creatures, on the other hand, are, as causes, essentially subordinate to the Creator, inasmuch as they can exist and act only in constant dependence on the ever present and ever actual conserving and concurring influence of the Creator.