Being has a dynamic as well as a static aspect; it not only is, but is active, a principle of activity: in a word, cause. This is what we have now to examine: being in its dynamic character, being as cause. Here again the problems are many and complex. Cause is one of the most frequently used notions in human thought; it is also one against which modern philosophy has directed some of its most pointed criticism; besides that, what the early philosophers taught in the matter is not easily gathered and sifted.
The chapter divides into three parts. First, as usual, we go to Aristotle and St. Thomas for their basic ideas on causality, and these in proper perspective. The conception thus gained is next put to test against the typical modern criticism of causality. The chapter then concludes with some extended remarks on the first cause, the consummation of the metaphysics of being.
Neither Aristotle nor St. Thomas has left a complete treatise on causality. Their thoughts on the subject, such as we have them, are fragmentary and, frankly, more often developed by occasion of other matters instead of independently. Still, it is possible to marshal these thoughts into two broad units, which reflect two principal prepossessions: 1) those which tell of causality as it relates to the doctrine of science, and 2) those which speak of it under the study of God (transcendent causality). The elaboration of causality in function of science is practically all Aristotle's, whereas its elucidation in reference to the study of God comes much more from St. Thomas.
1. Causality in Scientific Explanation 1
Aristotle's doctrine of the role of causality in scientific explanation is found, principally, in two works, the Posterior Analytics and the Physics, Book II in particular. In these studies two conclusions stand out, which for the present purpose it will suffice to pass in quick review.
a) Science is knowledge through the causes. This, in fact, is Aristotle's very definition of science, expounded in the Posterior Analytics and echoed again and again in other works, especially in Book II of the Physics and in Book B of the Metaphysics. In the Latinized Aristotle,
scientia est cognito per causas.
What Aristotle is saying is that we "know" (have science of) a thing when we know the cause (or causes) of it. Cause is the proper principle of scientific explanation.
Well and good, but we should also note what Aristotle is not saying. Neither he nor St. Thomas would have us look upon cause as a logical tool only. True, their doctrine of causality finds foremost expression within the framework of logical expositions, but this is not to suggest that they regard causality as void of validity in the real world. Quite the contrary; cause answers to the "why" of a thing and serves as principle of explanation for the very reason that it is, first of all, a principle of reality. Indeed, the principle of causality is essentially a principle of reality. St. Thomas says as much many times over; cause, he insists, as though anticipating future denials, bears directly on esse, existence, which means it bears on what is by nature most real, most concrete. Witness, for example, "the word 'cause' implies influence on the being (esse) of the thing caused." 2
b) Causal explanations in the sciences are possible under all four causes. This proposition is a hallmark of Aristotelianism. Since the causes are four in kind, so will be the causal explanations. In physical doctrine demonstration is by all four causes: material, formal, efficient, and final. Other sciences proceed more restrictively. Mathematics takes in formal cause only. Metaphysics, in the main, focuses on formal, efficient, and final cause.
c) In summary, cause may be considered in the order of objective reality and in the order of explanation or demonstration. Its primary order is that of reality; here, cause is precisely what gives a thing its being, and this through any of the four causes. In the derivative order of explanation cause is what gives the "why" or reason of a thing, and this, too, from each of the four causes.
Essentially, then, a cause is "that on which a thing depends for its being or its becoming." Which, in St. Thomas, is:
Causae autem dicuntur ex quibus res dependent secundum esse vel fieri.3
Analyzing this definition we find that causality necessarily implies these three particulars:
1) a real distinction between cause and effect
2) a real dependence of being
3) consequently, priority of the cause to the effect
2. Causality in Theology
So far we have spoken of cause as it impinges on the order of physical explanation, the order of experience. But this application of causality, even though it satisfies the true notion of cause, is not the whole of it. Causality in its wider range, in its metaphysical or transcendent mode, is seen in the study of God, where the central problem is precisely his existence, or the demonstration of it. Aristotle had already provided such a demonstration, the argument for the prime mover, fortifying it with all the rigor of his philosophical genius :1 This famous argument, stripped of its cosmological overlay, is retained by St. Thomas, who accords it first place in his Five Ways, still the classical proofs of God's existence.5 We do not intend, however, to make a detailed study of the Thomistic proofs. What follows is but three of them, and these in sketch: the argument for the prime mover (First Way), the proof from the degrees of being (Fourth Way), and, in barest form, the proof from finality (Fifth Way). The second and third proof, from causality and contingency (possible being), are mentioned in passing.
a) The argument for the prime mover. For the details of the argument as presented by Aristotle the reader is referred to the analysis we made of it in an earlier volume.6
St. Thomas, as we have said, keeps only the essentials of the argument, namely its metaphysical bases, which are not undermined by shifts in physical theory.
The argument, both in Aristotle and St. Thomas, begins with the fact of motion. It encompasses not only local motion, or the physical changes observable by the senses, though these of course come first to mind. Any becoming, any transition from potency to act can be taken as a starting point. If St. Thomas cites a physical change, this is no more than a pedagogical device.
Given motion, two principles are introduced in proof of a prime mover. First, "whatever is moved, is moved by another" - quidquid movetur ab alio movetur. This is the principle of causality in the more usual Aristotelian formulation of it. Motion, the principle intends, involves transition from potency to act, which is not possible except by agency of another, by a cause in act.
The second principle is "there can be no infinite regress in an essentially ordered series of movers." One mover may be moved by another, but if the series of ordered movers were infinite, there would be no first or unmoved mover, consequently no second or moved movers. More generally, in every order there must be a first, which, as principle or originator of the order, has necessarily to transcend it, to be outside of it. Thus, the order of moved movers requires a first mover, moved by no other. This mover, concludes St. Thomas, all men identify with God.
Such, in broad stroke, is the argument for the prime mover, which, it is plain, rests on the principle of causality. Of this principle we shall have more when addressing ourselves to the critical justification of it. What we wish here to remark is that the second and third proof of St. Thomas (his Second and Third Way) follow the same general pattern. The second proof begins with the order of efficient causes, such as experience shows us, and argues to a first efficient cause, which, transcending every series of caused causes, is caused by no other. The third proof proceeds from the palpable contingency of things to the affirmation of a first necessary being.?
b) The proof from degrees of perfection. This proof departs, or so it may seem, from the principle of causality. Whether or no, here for the moment is the thread of it.
The things of experience exhibit varying degrees of perfection. All things, for example, are good, but some are better; and all are true, but some are truer, etc. However, not all perfections are to the purpose of the argument - only those which do not of their nature imply limitation, pure perfections, as is commonly said. Perfections of this kind are not confined to categorical being, but are to be found in being generally. Pre-eminently they are the transcendentals: the one, the true, the good, and of course being itself. Because of their transcendental character they are realized analogically from being to being.
This is the empirical premise of the proof, the degrees of perfection. Then to the principle on which the proof rests, namely: a perfection is spoken of as more or less only in reference to something that has the perfection to a maximum. Consequently, there is something which is most true, most good, and (it follows) most being.
But (to complete the proof) that which is the maximum in any order of perfection is the cause of all perfections existing in that order. Hence, there is something which is to all other beings the cause of their being, their goodness, their every perfection; and this we name God.8
Thus the proof, the interpretation of which has occasioned much controversy. On the surface the appeal, it would seem, is not to the principle of causality: from the degrees of a perfection the maximum of this perfection is immediately inferred. On the lips of St. Thomas, however, the proof is not complete, and does not formally terminate in God, until the maximum in a given order of perfection is set forth as the cause of all lesser realizations of the same perfection. Consequently, the principle of participation, which is admittedly in the foreground, still implies the principle of causality. All the same, the proof from degrees of being does throw new light on the relation of creatures to God, presenting a fuller view, as it were, than appears through the avenue of causality alone. St. Thomas, for that matter, was not one to depreciate the doctrine of participation, his treatise on God being inspired by it throughout.9 Even so, we must not find in this treatise what is not there, intimations of a metaphysics that would oppose and perhaps supplant the metaphysics via causality. In St. Thomas, participation and causality are not pitted against each other, nor does the latter have to give way to the former, as though they were incompatible.
b) The proof from finality. This proof, last of the Five Ways of St. Thomas, starts from the finality and order seen in the physical universe.
Where (runs the argument) there is order, there is intention; and if intention, intelligence. Ultimately, then, there must be some intelligent being which directs all things of nature to their end. This being is God. This proof is much favored in more popular works on the existence of God, and there is no doubt that the presence of order in the world is a theme well-suited to the purpose. The proof, for all that, is not without its pitfalls; to make its mark it has to be handled with care.
d) Conclusion: causal dependence as the common element in the proofs of God. The arguments presented constitute distinct proofs demonstrating, each from its particular standpoint, the existence of God, the first cause. Yet all the proofs have this in common: the metaphysical principle that contingent being, or being which does not have its sufficient reason of itself, presupposes being that does, the being that exists of itself and to which contingent being is related by the bond of causal dependence. Being which is not of itself can only be of another - of another that is of itself. All theology, not to say philosophy, rests on this fundamental, the causal inference. Is this inference legitimate, well-founded? The question has now to be examined.