(Greek aitía, aítion, Latin causa, French cause, German Ursache; from the Latin both the Italian term cosa and the French chose, meaning "thing", are derived).
Cause, as the correlative of effect, is understood as being that which in any way gives existence to, or contributes towards the existence of, any thing; which produces a result; to which the origin of any thing is to be ascribed. The term cause is also employed in several other suppositions, philosophical, scientific, legal, etc., to which reference will be made in the course of the present article. The description just given is that of cause taken in the philosophical sense, as well as in its ordinary signification in popular language, for, strictly speaking, cause, being a transcendental, cannot receive a logical definition. It is that also commonly advanced as a preliminary to the investigation of the nature of causality, in the schools. Although the ideas of cause and of causality are quite obviously among the most familiar that we possess, since they are involved in every exercise of human reasoning, and are presupposed in every form of argument and by every practical action, a very great vagueness attaches to the popular concept of them and a correspondingly great ambiguity is to be found in the use of the terms expressing them. In view of this fact, it will be necessary to clear the ground traversed in the main portion of the present article by stating that it is concerned, not so much in treating of individual causes considered in the concrete, as with the analysis of the idea of causality underlying and involved in that of every cause. There is also a psychological, as well as a metaphysical, aspect of the subject, which ought not to be lost sight of, especially in that part of the article in which the more recent speculations with regard to causality are touched upon.
As a matter of fact, all mankind by nature attributes to certain phenomena a causative action upon others. This natural attribution of the relationship of cause and effect to phenomena is anterior to all philosophical statement and analysis. Objects of sense are grouped roughly into two classes--those that act and those that are acted upon. No necessarily conscious reflection seems to enter into the judgment that partitions natural things into causes and effects. But when we proceed to ask ourselves precisely what we mean when we say, for example, that A is cause and B effect, that A causes B, or that B is the result of A, we raise the question of causality. Whatever answer we put forward, it will be the statement of our conception of causation. It will be the expression of our judgment as to the actual relationship between A and B involved in the conception of the one as cause and of the other as effect. It will probably be found, when we attempt to formulate any answer to the question, that much more is involved than we had at first sight thought; and, since the investigation we should pursue would probably proceed upon lines analogous to those upon which philosophy has, as a matter of fact, travelled, it will not be amiss to trace the history and development of the problem concerned with causes and causality, and to set down briefly the various solutions advanced. We shall begin, therefore, with the first crude conception of power or efficiency, and pass on through the stages of hyloism and idealism to the full analysis of cause and statement of causality made by Aristotle. This will be considered merely in outline, as filled in in the following more detailed account of the doctrines of the Schoolmen upon the subject, who, while adopting it in all its main lines, in several respects modified the teaching of the Stagirite. The critical attack upon the possibility of a knowledge of causality, made by the Scottish sceptic Hume, will next be considered in its relation to the reply of the Common Sense School, as represented by Reid. The doctrine of Kant, with its double sequence of idealism and materialism, will be touched upon briefly; and, with a comparison of the mechanical concept of modern science with regard to causes and the more fundamental metaphysical analysis of causality, the philosophical treatment of the topic will be brought to an end.
Before the inception of the pre-Socratic schools of Greek philosophy, the first rude and popular conception of causes was mixed up with much that was extravagant and, in the proper sense of the word, superstitious. The powers of nature were personified, and thought of as intelligent and wilful. They were conceived of as far more powerful than man, but uncertain and capricious, so that it was necessary to propitiate them and enlist their favour by offering them sacrifices and praying to them. Thus there was the idea of power, and a loose attribution of effects to one or another of the natural forces that had vaguely come to be looked upon as causes. It was in order to provide a ground of unity, rather than thus to distract causes, that the early philosophers took up their search for the principles of things. The problem immediately before them was that of explaining similarity and diversity, as well as change, in the visible world. With them, though the term aitía was employed, and even occasionally in several of the senses in which Aristotle later distinguished it, the commoner term was arché, with which the former was apparently generally interchangeable. By this term a principle was designated that, in some vague sense, approaches in meaning to the material cause of the Stagirite. It was used to signify an entity prior to existing entities, and yet in some way coexisting with them and furnishing the ground or reason for their existence. But it did not connote the idea of cause in the strict sense, namely as that which actually gives being to its effect, such as is involved in later concepts of causality and is derived from the observation and analysis of the conditions of physical change. The problem thence arising had not yet been definitely set. The task of the philosophers of these early schools was the investigation of nature, with, for result, the discovery of its elemental constituent or constituents, its primordial principles. Thus the representatives of both the Ionian and Eleatic Schools, in reducing all things to a single purely material basis, or to several bases, assign, indeed, a principle that may be considered as a concrete cause, but do not raise the real question of causality, or give any satisfactory account either as to how one thing differs from another or as to how things can come to be at all. Nor, in explaining diversity and change by assigning heat, rarefaction, condensation, arrangement in space, number, etc., was more than an attempt made to call closer attention to the fact of causation and to determine more accurately than did popular opinion what were the concrete causes by which things came to be what they are. This, obviously, is not an analysis of causality, and in no sense really touches the heart of the question. It hardly calls for the remark that at most the causes, or more properly the principles, assigned, even if understood in the sense of inherent differentiating principles, were such as would account for no more than an accidental diversity, leaving all things, the diversity of which was the very point to be explained, really identical in substance.
The progress from this first search for the elemental principles of being to the later investigation and interpretation of alteration, or change, in itself was gradual. Something had to be found that would account for the regularity of the succession of phenomena in the physical world, as well as for their diversity and alteration. The Pythagoreans put forward their doctrines of number as an explanation; Plato, his theory of ideas. Thus, in his advance upon his predecessors, he clearly allows, in a very real sense, for formal causes of existence. But he does not specify the nature of these ideas, other than as substances, separate from the individual entities that they cause. In some manner not fully explained, these individual entities are precisely what they are by participating in the idea. In different passages in his writings Plato alludes to the relation between the ideas and the concrete entities as a participation, a community, or an imitation. Thus he states the fact of similarity in the essences and processes of the physical world, but does not offer any explanation or definite account of it. In common with the earlier nature philosophers, Plato assigns concrete causes but does not attempt to give any solution of the real problems of causality. Not until Aristotle formulated his famous doctrine of the four causes of being can it be said that the question was envisaged with sufficient clearness to admit of exact presentation or fruitful discussion. Instead of explaining diversity in the physical world by a reference to a common underlying principle and an accidental modification, either fortuitous or designed, proceeding from it and in it--at best the crude makeshift of an incipient philosophy that has yet to state correctly the problem to be solved, instead of looking outside the object, or effect, for that which specifies it, and finding a substance entirely separated from it, to which its substantial existence in the world of phenomena, in some cryptic manner, is to be attributed, Aristotle instituted a profound inquiry into the essentially diverse modes in which any one thing can be said to contribute to the existence of any other. In so doing he changed the nature of the inquiry. The result was not only the discovery of the four causes, but a solution of the really far more important question of causality. There is no doubt but that his teaching is, in a very real sense, a synthesis of all that had gone before it; but it is a synthesis in which no one of the preceding doctrines is adopted precisely as it stood in the earlier systems. The secret which governed the adaptation of the currently accepted "principles" and made the synthesis possible, lay in the signification that he gave to the formal cause. The task he had to perform had ceased to be that of discovering merely physical constituents or principles, and had shifted to the fundamental issue of metaphysical inquiry. Aristotle gives the opinions of his predecessors at considerable length in the "Physics", and again in the "Metaphysics", in which he submits them to a careful analysis and rigorous criticism. But the elements of his own doctrine with regard to the four causes, as causes, were there in solution. The signification of the term arché, already used, was sufficiently comprehensive to include that of aitía, since all causes come necessarily under the head of principles. The Ionians of the older school had dealt with matter. Later Ionians had treated vaguely of efficient causes. The method and moral teaching of Socrates had convolved and brought out the idea of the final, while Plato had definitely taught the existence of separated formal, causes. All these factors contributed to the result of his inquiry, and the splendid historical criticism and review to which he submits the earlier philosophers and their teachings on this point show not only his wide and profound acquaintance with their doctrines, but his readiness also to credit them with whatever they had advanced that at all made for knowledge. Still, to this point, as has been said, it was a question of principle rather than of cause; and, when of cause as such, of cause considered in the concrete rather than of the causality of causes.
The problem, then, for Aristotle, took the form of an analysis of essences in such wise as to perceive, separate, and classify those principles which, in conspiring to bring the essence of any effect, object or event, actually into existence, as it were, flow into it. For the idea of cause is of that which in any way influences the production of an effect as an essence. And, to declare the manner in which such causes, once discovered, are found to correspond, and play their several parts in causation, will be to state causality. Now, as our notion of principles in general, whether in the being, in the becoming, or in the understanding of any thing, is primarily derived from observation of motions taking place in space, so our notion of cause is derived from observation of changes, whether local, quantitative, qualitative, or substantial. The explanation of any change leads to the doctrine of the four distinctions, or classes, of causes as formulated by Aristotle. They were:
The teaching of Aristotle is that which substantially passed current in the medieval schools. With certain important modifications concerning the eternity of the material cause, the substantiality of certain formal causes of material entities, and the determination of the final cause, the fourfold division was handed on to the Christian teachers of patristic and scholastic times. As Aristotle had developed and improved the doctrine of Plato with regard to inherent substantial forms, so the leaders of Christian thought, guided in their work by the light of revelation and the teaching of the Church, perfected the philosophical teaching of Aristotle. It is not, indeed, advanced that the Christian philosophy of this period was merely theological; but it is contended that certain purely philosophical truths, verifiable in and by philosophy, were obtained as a result of the impetus given to metaphysical research by the dogmas of revelation. This is not the place for enlarging upon such a topic except in so far as it is directly pertinent to the question of causes; and it is principally in other matters that the contention obtains. Still, at least in the three cases to which allusion has just been made, it is true that speculation was helped forward on the right lines by the teaching of the Church. The truth of the contention is patent. In the patristic Period, particularly in the works of St. Augustine, who was a Platonist rather than an Aristotelean, and in the scholastic period, the foremost representative of which is St. Thomas Aquinas, the doctrine of the four causes of being is set forth in connection with the modifications noted. The theory of causality, as held and taught in the Middle Ages, and as taught in the schools today, will in this section be exhibited in some detail.
"The ancient philosophers came to the knowledge of truth by degrees and slowly", writes St. Thomas.
For at first, being as it were less cultivated, they did not recognize any beings other than sensible bodies. And those of them who acknowledged movement in them only admitted movement as to accidents, as in rarity and density, aggregation and disgregation. And, supposing that the substance of bodies was untreated, they assigned certain causes for accidental changes of this kind, as, for example, friendship, strife, intellect or something of this nature. Proceeding, they distinguished intellectually between the substantial form and the matter, which they considered as uncreated; and they perceived that substantial transmutation takes place in bodies with respect to their substantial forms. (Summa Theologica I:44:2)
The last sentence of this passage gives the basis of the Scholastic doctrine with regard to causes. "Consider", a Scholastic would say, "a substantial change--that is to say, a change in which one substance, made known to the understanding by its qualities, ceases to be what it was in the instant A, and becomes, in the instant B, another substance. In order that such a change should be possible, four things are necessary: namely,
The material cause, as presented in the Scholastic system of philosophy, fulfils the conditions of a cause as given above. It gives being to the effect, since without it this could neither exist nor come into being. Though it is conceived as an essentially incomplete subject, as a merely passive potentiality, it is distinguished from the complete effect, to the becoming and being of which it contributes. The diversity of primordial matter from the forms which actuate it is exhibited by the consideration that there is an essential distinction between the subject of change and the states, modifications, or determined natures from which and towards which the change is conceived as acting. Hence primordial matter is reasonably held to be a reality, belonging reductively to the category of substance, and determinable to every kind of corporeal substance by reason of its essential ordination to the reception of a form. Quantity is said to be a consequent of material substances by reason of the matter entering into their physical composition; and by matter, as quantified, forms, specifically the same, are held to be numerically individuated.
The doctrine of the school with regard to formal causes must be understood in the light of the thesis that all forms are, of their nature, acts, or actualities. The formal cause of material entities has been described as that substantial reality which intrinsically determines matter in any species of corporeal substance. It is conceived as the actuating, determining, specifying principle, existent in the effect. It is a substance, not of itself as form, but reductively, as the quidditative act, as the material cause belongs to the same category in the sense of being a receptive potentiality. But substantial form, with which we are here dealing, is not of its nature either dependent or independent of the matter that it informs; or actuates. Certain substantial forms are said to be drawn from the potentiality of matter--those, namely, that for the exercise of all their functions are totally dependent upon material dispositions or organs. Of this nature are said to be all substantial forms, or formal causes, specifically below that of the human being, i.e. the soul of man. This, as intrinsically independent of matter in its chief functions of intellection and volition, is, although the formal cause of man, as such, held to be immaterial, and to necessitate a special and individual creative act on the part of God. While the material cause of corporeal entities is one, in the sense that it is one indeterminate potentiality, the formal cause is said to be one in the sense that one substantial formal cause only can exist in each effect, or result, of the union of form and matter. For formal causes, as the specifying factors in diverse corporeal entities, are diverse both numerically and specifically. They are so specifically in that they proceed in an order of varying perfection, from the formal causes of the simple elements upwards, just as the various effects, or results, of the union of matter and form, which are specified by them, proceed in an order of varying perfection, to the lower of which, in each subsequent grade, a higher is super-added. They are numerically diverse, in the same species, because of the differentiation that accrues to them on account of their reception in quantified matter (materia signata).
Consistent with this teaching is that in which the angels are said to be distinguished specifically, and not numerically, as lacking the material subject by which substantial forms of the same species are differentiated. In the same way the human soul, when separated from the body at death, is held to retain its "habit" towards the quantified matter that it actuated as formal principle, and from which it received its differentiation from all other human souls. In a sense similar to that of substantial forms specifying primordial matter, accidental formal causes are conceived as informing corporeal substances already in existence as entities. The causality of the substantial formal cause is shown in the same manner as that of the material. It concurs in the being of the effect, or result of the union of matter and form, as actually constituting this in its proper and specific essence. Yet it is distinct from it in that it does not include in itself matter, which the composite effect does. A parallel consideration will show the nature of the causality of accidental formal causes. The specific qualities of material substances, as well as of immaterial, are said to depend upon their formal causes. It may be noted that, while both the material and the formal principle are, properly speaking, causes, in that they contribute, each in its proper manner, towards the resultant effect, their causal nature is intrinsic. The informed matter is the effect, produced and sustained by the act of information. Form and matter are physically component parts of the effect. The theory derived from an examination of corporeal changes, both accidental and substantial, that has just been outlined, is that commonly known as Hylomorphism. It permeates the whole of Scholastic physical science and philosophy and is employed, both as to terminology and signification, in the exposition of Catholic theology. In this place it will be well to note that the terminology and meaning of this doctrine are not only consecrated to theology by the usage of theologians, but have also been employed in the solemn definitions of the Church. In the general Council of Vienne it was defined that whosoever shall presume to assert, defend, or pertinaciously hold that the rational or intellective soul is not the form of the human body, of itself and essentially, is to be considered as a heretic. (Cf. "Conc. Viennen. Definitiones...ex Clementinâ de Summâ Trinitate" in Denzinger, "Enchirid.", n. 408.) This teaching was reasserted in the decree of Pope Leo X, in the Fifth Lateran Council (Bull, Apostolici Regiminis), and again by Pope Pius IX, in a Brief to the Cardinal Archbishop of Cologne, concerning the books and teaching of Günther (1857).
The efficient cause is that which, by its action, produces an effect substantially distinct from itself. It is denominated efficient on account of the term produced by its action, i.e. the effect itself, and not necessarily from any presupposed material principle which it is conceived as potent to transform. The action, or causality, of the efficient cause is conceived as one which educes the actuality of the effect from its potentiality. This it is held to do in virtue of its own actuality, though precisely how no one has ever explained. No explanation of the essential nature of the action of the efficient cause would seem to be possible. St. Thomas Aquinas tells us that
an effect shows the power of the cause only by reason of the action, which proceeds from the power and is terminated in the effect. But the nature of a cause is not known through its effect except in so far as through its effect its power is known, which follows upon its nature. (Contra Gentiles, III, lxix, tr. Rickaby.)
Both the fact of efficient causality, and an account of its mode of action, as to accidents, are thus expressed by St. Thomas, in answer to the objections of "some Doctors of the Moorish Law":
Now this is a ridiculous proof to assign of a body not acting, to point to the fact that no accident passes from subject to subject. When it is said that one body heats another, it is not meant that numerically the same heat, which is in the heating body, passes to the body heated; but that by virtue of the heat, which is in the heating body, numerically another heat comes to be in the heated body actually, which was in it before potentially. For a natural agent does not transfer its own form to another subject, but reduces the subject upon which it acts from potentiality to actuality. (Op. cit., Bk. III, lxix.)
The same argument, mutatis mutandis, would likewise hold good if applied to the efficient causes of substances. The efficient cause, unlike the material and the formal, is thus seen to be entirely extrinsic to its effect. It is held to act in virtue of its form. The fact and mode of this action is given in the above quotation from the "Contra Gentiles"; but the precise nature of the action, or relation, between the efficient cause and its effect is not stated. It is quite clear that the accident, quality, power, or motion in the cause A is not held to pass over into the effect B, since a numerically new one is said to be reduced from potentiality. Equally clear is it that nothing of the first efficient cause is supposed to pass over into its effects, as creation is said to be ex nihilo sui et subiecti; and there is nothing in God to pass over, since all that we conceive of as in God is God Himself. Consequently it would seem that the concept of efficiency in general includes no more than the activity of the cause as producing the effect by educing an accidental or a substantial form from the potentiality of matter. In the one case of forms not so educible, the efficient cause (God) creates and infuses them into matter. (Cf. In III Phys., Lect. 5.)
There are many divisions and subdivisions of the efficient cause commonly made in Scholastic treatises, to which the reader is referred for a more complete development of the subject. Under this head, however, will be added the principal dignities, or axioms of causality, as laid down by the Schoolmen:
The final cause, or end, is that for the sake of which the effect, or result of an action, is produced. It is distinguished in the following manner: I (1) The end considered objectively, or the effect itself as desired by the agent; (2) the end formally considered, or the possession or use of the effect. II (1) The end of the efficient operation, or that effect or result to which the operation is directed by the efficient cause; (2) the end of the agent, or that which he principally and ultimately intends by his operation. III (1) The end prior to the activity caused by it, both as cause and in the line of being; (2) the end prior to the activity as cause, but posterior to this in the line of being. There are other divisions of the final cause, for the details of which the reader is referred to the literature upon the subject. The causality of the final cause is to be referred to its appetibility. "As the influx of the efficient cause is in its act, so the influx of the final cause is in its being sought after and desired" (St. Thomas, De veritate, Q. xxii, a. ii.) That it is a true cause Aquinas shows in the following words:
Matter does not acquire form, except according as it is moved by an acting cause (agent); for nothing reduces itself from potency to act. But the acting cause does not move, except by reason of the intention of an end. For if the acting cause were not determined to some effect, it would not act to produce one rather than another. In order, therefore, that it should produce a determined effect, it is necessary that it should he determined to something certain as end. (Summa theol. I-II:1:2; cf. also In V Metaphysic., Lect. 2.)
The final cause, like the efficient, is extrinsic to the effect, the latter being the cause of the existence of the former, and the former causing the latter, not in its existence, but as to its activity here and now exercised. Efficient causes acting towards ends are distinguished as: (1) acting by intelligence; or (2) acting by nature. Ultimately, the tendency of the operation of the latter class is resolved into operation by intelligence, since the determined operation following on their nature is, and must be, assigned to an intelligent first cause, either of a particular series, or of all series: i.e. God. Thus deliberative operation is seen not to be of the essence of operation towards the attainment of ends. It is shown that, in no one of the four classes into which causes are differentiated is an infinite progression possible; and, upon the doctrine advanced as to causality in general, and the four classes of causes in particular, are based arguments demonstrating rationally the existence of God. It may be of interest to refer in this section to the exemplary cause, or exemplary ideas, as conceived by St. Thomas. He writes (Summa theol. I:15:1):
In all those things that are not generated by chance, it is necessary that form should be the end of the generation of each. But the efficient cause [agens] does not act on account of the form, except in so far as the likeness of the form is in it. And this happens in two ways. (1) For in certain efficient causes the form of the thing to be made pre-exists, agreeably to natural essence, as in those things that act by nature; as man begets man, and fire produces fire. (2) But in others it pre-exists agreeably to intelligible essence; as in those things which act by intellect; as the likeness of the house pre-exists in the mind of the builder.
He concludes that, since the world is not the result of chance, there is an idea (in the succeeding article of the same question, many ideas) in the Divine mind, as the archetype forms of things. But these ideas are the essence of God understood by Him as imitable in diverse modes on the part of His creatures. In this sense, perhaps, did Aristotle identify form, end, and moving cause. In the imitability on the part of creation, St. Thomas finds the secret of the world of phenomena. Viewed with his theory of causality as exposed above, it is perhaps the most complete and consistent explanation that has ever been given of the problem. When we find Spinoza putting forward substance, with its two attributes of thought and extension, determined to modes (unreal as these ultimately turn out to be); when Berkeley teaches that what we take to be causal changes in the phenomenal world are illusory, that there are no secondary causes, and that God and the human mind alone are real; when Hegel posits the unfolding of thought as the cause of phenomenal change, or Schopenhauer will manifesting itself in phenomenal succession--we seem to have found some clue to the labyrinth of causality, some common ground of unification. But it is at the cost of doing violence to our sense perception and immediate necessary judgments that the unification is brought about. In the Scholastic solution of the problem a ground of unification is provided in the transcendence, rather than the immanence, of the first and original source of all efficient causality. Moreover, with the isolation of the four causes and the declaration of their relationships and interaction, a coherent account is given of the working of secondary causality, as a matter of fact, in the phenomenal world.
There is one aspect of the present topic that usually has a treatment apart from the more general question of causality. How, it is asked, can causal action be conceived as taking place between soul and body--between mind and matter, or between matter and mind? For a fuller statement of the answer to the latter part of this question the reader must be referred to the article EPISTEMOLOGY. It may be pointed out here, however, that in the Scholastic philosophy, man is not regarded as being a double entity--i.e. body+soul--but as a single one. The soul is the true and proper form of the body, which is its matter. It is, consequently, man who sees, hears, feels, etc., just as it is man who understands and wills. The communication from the outside world to his consciousness is made by the action of phenomena upon his organs of sensation. He is in touch with things external to himself through the medium of their "sensible species". These, as phantasmata, under the abstraction of the "acting intellect", are transformed into "intelligible species". Thus, from the observation of causal action in the concrete, man rises to a true intellectual knowledge of causality in itself.
The first part of the question includes two issues. Man wills and performs actions, either becoming the efficient cause of effects, or causing efficient causes to act. God wills and creates the world. In the second case philosophy must confess to a mystery. It is held to be proved, by a consideration of the multiplicity and mutability of the entities that together form the world, that they have their origin in that one supreme and immutable entity which is God. It is further held to be proved that they are neither produced out of Him nor out of an already existing subject. To such a production of effects is given the name Creation. How God, as efficient cause of creation, acts, it is impossible to conceive. In the first case, will is a faculty of the soul, which is the substantial form of man. Consequently a man wills, rather than the will (or the soul), and, by reason of the intimate union of body and soul as matter and form (i.e. one suppositum, thing, or person), man acts. As informed by "soul" man is capable of willing to act and of acting; as body, or matter informed by "soul", he is capable of acting upon other bodies. For a more complete development of this point see PSYCHOLOGY.
Though the Scholastic philosophy never fell into complete desuetude, nor ever lacked distinguished exponents of its principles, the upheaval of the sixteenth century was productive of new systems of thought in the development of which the idea of causality was profoundly modified, and ultimately was, in any intelligible sense, to a great extent abandoned. In this period two main lines of thought with regard to causes and causal action are pursued. On the one hand there is a tendency to revert to a purely mechanical conception, on the other to a purely idealistic one. The later Schoolmen had, by indulging largely in stereotyped, and often useless, speculations, in which a perplexing number of concrete cases of causality figure, brought Scholasticism into disrepute; while a general vague unrest and a desire for practical results from philosophy contributed to the formation of a new empirical system, constructed upon the principles of what is called the scientific method.
In his "Instauratio magna", Bacon gave impetus to the movement. While accepting the traditional fourfold division of causes, he was of opinion that any speculation with regard to final causes is fruitless. The material cause, also, is not a proper subject for investigation. Even the efficient cause, except in given conditions, is such as cannot lead us to knowledge. Forms alone help the interpreter of nature and this in the practical sense that by a knowledge of forms he is in a position to become an efficient minister of nature. What is meant by form is not very clearly explained; but it is fairly safe to say that by it Bacon intended something approximating in meaning to the eîdos of Aristotle. Both Bacon, as is to be seen in his treatment of heat in the "Novum Organum", and Descartes make motion the cause of the "apparently diverse changes in nature". The latter entirely rejected the Scholastic system of formal causes, and considered matter as entirely inert. Hence diversify and change are to be accounted for immediately by motion+matter; while ultimately the sole efficient cause of all things is nothing else than the Will of God.
The opinion of Descartes on this head, together with his complete dualism of body and mind, led to the theory of causality, already advanced by certain Arabs in the eleventh and twelfth centuries, and known as Occasionalism. This is one of the most curious causal theories that has ever been put forward, and merits some notice. The Occasionalists--Malebranche, Geulinex (Leibniz)--taught that created things do not themselves possess any effective activity, but are merely occasions in which the activity of the sole efficient cause, God, is manifested. A cause in nature does not produce any effect; but is the condition--or, more properly, the occasion--of the production of effects. Similarly, there is no causal connection or relation between body and soul. When God acts in nature producing effects, or things, occasioned by the previous existence of other things, He acts directly likewise upon our minds producing the corresponding idea of causal change. When we will, our volition is no more than the occasion of His acting on our bodies and effecting a movement, or change, corresponding to our willing. Akin to this explanation of the origin of our concepts of causality and of volition, is the doctrine of Leibniz on "pre-established harmony" between the soul-monad and the material-monads. Conformably to the theory of the Occasionalists, there is no transeunt, but only immanent, action to be admitted in causal changes. Several of the considerations given above in the section developing the doctrine of the Schoolmen anticipate this theory as an objection, notably that which deals with the reductive nature of efficient causality by which the potential is said to become actual and thus constitute the effect.
The problem of causation, for which a solution was advanced by the Occasionalists in the introduction of God as sole efficient cause, was disposed of by Hume in a still more drastic manner. His critical examination of the idea of causality issues, in full accordance with his sensistic principles, in sheer scepticism. Having previously reduced mind to no more than a succession of perceptions, he declares: "To me there appear to be only three principles of connection among ideas, namely, Resemblance, Contiguity in time or place, and Cause or Effect" (Works, IV, 18). Thus, for Hume, causality is no more than a relation between ideas. It is not an a priori relation, "but arises entirely from experience, when we find that any particular objects are constantly conjoined with each other" (ibid., 24). However, we can never comprehend any force or power, by which the cause operates, or any connection between it and its supposed effect. The same difficulty occurs in contemplating the operations of mind on body.... So that, upon the whole, there appears not, throughout all nature, any one instance of connection, which is conceivable by us" (ibid., 61 sqq.). Whence, then, does our conception of cause come? Not from a single observed sequence of one event from another, for that is not a sufficient warranty for us to form any general rule, but from the conjunction of one particular species of event with another, in all observed instances. "But there is nothing", he writes,
in a number of instances, different from every single instance, which is supposed to be exactly; except only, that after a repetition of similar instances, the mind is carried by habit, upon the appearance of one event, to expect its usual attendant, and to believe that it will exist.... When we say, therefore, that one object is connected with another, we mean only, that they have acquired a connection in our thought, and give rise to this inference, by which they become proofs of each other's existence (p. 63)
Hence Hume defines cause as that object, followed by another, "where, if the first object had not been, the second would never have existed", or "an object followed by another, and whose appearance always conveys the thought to that other" (ibid.). In this doctrine Hume advances a psychological explanation of the origin of the idea (habit), but inculcates an utter scepticism as to the reality of causation.
Hume's position was sharply attacked by Thomas Reid, who invoked "common sense" to confute him, principally on account of the consequences of his scepticism in the region of natural theology. But Reid, mistaking the doctrine of the Schoolmen as to perception--he supposed that Scholasticism taught that the species sensibilis was that which is perceived, rather than that by which the sensible object is perceived--went so far as to assert that sense perception is the same as intellectual judgment. Reid was accused by Kant of having altogether misunderstood the point of the question raised by Hume; and was defended by Galluppi, who instead makes Kant mistaken as to Hume's meaning. Kant represents Hume as saying: "Metaphysical causation is not in the objects observed; therefore it is a product of the imagination based on custom or habit." This he alters to: "Causation is not in the things observed; therefore it is in the observer." But Hume's real argument is: "Metaphysical causality is not in the things observed; therefore it cannot be in the observer, in whom all is derived from observation." This, he says, Reid thoroughly understands, and pertinently retorts: "As a matter of fact the concept of metaphysical causation is in the intellect; and, since it is not derived from the things observed, it must therefore be a subjective law of the observer." Had Reid not misunderstood the import of the species sensibilis his appeal to "common sense" would have given him a greater affinity to the Schoolmen. His division of first principles as necessary or contingent has the metaphysical in the first category. Among these he places the principle of causation, thus assigning it a place as a necessary first principle, prior to all experience and independent of it.
Thomas Brown, whose work was said by Mackintosh to be "all open revolt against the authority of Reid", agrees with Hume in resolving causality into invariable succession, but dissents from his theory that the idea has its origin in "habit", and contends, with Reid, that it is an intuitive, or first truth. His analysis of consciousness into "the whole series of states of the mind", and consequent denial that there is a consciousness capable of knowing its own states, is, however, in explicit contradiction with Reid's teaching. Thus, Reid having overlooked the point of transition from phenomenal observance to noumenal truth, Brown still further separates the two and prepares the way for Hamilton and Mill, the former of whom makes our notion of causality a belief dependent upon a powerlessness of our nature to think otherwise. The latter explains causality as uniform antecedence, the growth of human experience and not to be extended beyond the realm of experience. "In distant parts of the stellar regions", he writes, "where the phenomena may be entirely unlike those with which we are acquainted, it would be folly to affirm that this general law prevails." (System of Logic, III, xxi.)
Hume was the philosophical predecessor of Kant. We accordingly find in the "Kritik der reinen Vernunft" that, on the question of causality, the doctrine of Kant, to a considerable extent, is in substantial agreement with that of the Scottish sceptic. Where Hume posited a repetition of similar instances of connection, by the observance of which is set up a habit that accounts psychologically for the idea of necessary causation, Kant advances a regular succession of effect from cause. This regular succession, whatever it may chance to be in nature, is physical causation. But we cannot know anything of it a priori. There is, as far as we can discover, no reason why A should succeed to B, rather than to C, D, or E. Whatever the order of succession is de facto, we must learn by observation, since there is nothing in the nature of things, so far as we can judge, to make one the consequent of another rather than of some third. We do, however, know--and this a priori--that the order of succession, whatever it may actually happen to be, is, and must be, regular. This follows from a fundamental position of the Kantian philosophy. Space and time are a priori concepts, or subjective forms. All phenomenal successions, whatever they may be, exist in time and space. Or, rather, time is regular succession, just as space is regular reciprocal occupancy. Hence, whatever the things existing in space may de facto be, and however the order of succession may happen to take place, the one must be definitely determined to some set of reciprocal relations, and the other must be one, definite, and irreversible. We arrive at a knowledge of the one actual order of succession, of which some one order must be, by observation; but the datum of a regular order is known beforehand. Efficient causality, therefore, in the world, as regular succession, is an a priori item of knowledge. What the precise order is remains to be discovered, and its formulation is the formulation of natural laws. Between cause, then, and effect there is a constant and necessary relation; but the effect is not in the cause. In the scheme of categories developed by Kant, cause and effect fall under the head of Relation, together with substance and accident, and action and passion. But the relation is known through experience, and consequently is of no value beyond the realm of experience. No inference can be made from it to God, as cause. The cosmological proof is thus rejected by Kant.
From Kant onwards the two lines of thought already noted become yet more clearly marked. Indeed the elements of both are to be found in his own writings. On the one hand, the idealistic development of philosophic thought reaches its expression in Hegel, Schopenhauer, etc. On the other, science, as such, limits itself more and more to purely mechanical concepts. The problems of causality are referred to the idealistic standpoint, or else are treated in terms of matter and motion, with no reference to the essences of the effects.
With Hegel causality takes the form of the development of the Idea, as the Absolute in itself (an sich), through its manifestation as otherness (für sich), and back to identity (an und für sich). All that is, in the way of cause, is the working out, or unfolding, and coming back to itself, of the Absolute Idea. Being is becoming. The Hegelian notion of Being as essentially pure thought issues naturally in a kind of inversion of the ordinary notion of causality; for, with Hegel, the notion of causality is causality itself. Although he opposed Hegel and his philosophy with great violence, the system of Schopenhauer is not greatly dissimilar to this. Schopenhauer substitutes Will for Idea. The world, and its processes, are the objectivized form of the Will. But, strictly speaking, Will cannot be considered as cause and effect. Rather are these but two aspects of one and the same thing. Thus Schopenhauer (as does to some extent von Hartmann) reduces causality to the universal operation of a single ideal principle. Both attenuate the idea of it, Schopenhauer by his extreme doctrine of relativity, von Hartmann by his conception of the all-oneness of the Unconscious. According to Schopenhauer, we call cause that state of objects which is followed by another state (i.e. the effect), on account of the principle of sufficient reason of becoming--principium rationis sufficientis fiendi.
This last notion of causality, as mere sequence, but without any idealistic ground to account for it, is that which principally obtains in current science. A given event, in the instant A, is uniformly followed by a second given event in the instant B. No implication of power, or dependence, is conceived or stated. Similarly, a group of events, in one instant, is followed by another group in the next; the total sum of things comprising the world is succeeded by the total sum of things comprising the world in two succeeding instants. In all these cases, as far as they are considered by science, the event or events of the prior instant are always the cause of what follows, provided the succession is invariable. Thus the same thing may conceivably be, and is sometimes said to be both cause and effect, identical in all respects but that of succession in time. There need be no necessary contradiction between such a view and that of philosophy; for science, as such, does not consider the questions of metaphysics or seek to determine the essential causes of beings. A relationship, given that it is invariable, as the unconditional constant succession of John Stuart Mill, between the two or more phenomena, is all that science demands and, under the particular abstractions with which it deals, this is enough to ensure scientific results. A knowledge of the conditions of the existence of certain phenomena is the principal aim of science; and this is strictly pursued by observation, experiment, and the application of mathematical methods. There is, consequently, no radical opposition between the two provinces of knowledge, since both the ends sought and the means employed in their search differ. Indeed were a man of science to make any pronouncement as to the nature of essential causes or their mode of causality, he would have overstepped the boundaries drawn by his science and declared himself a metaphysician. As a matter of fact, there have not been wanting scientists, whose habit of mind and training are entirely scientific and in no sense metaphysical, who have done this very thing and attempted to give a scientific solution of a purely metaphysical problem. There will be no need to give any detailed account of such an attempt, the success of which is obviously impossible. The scientific means at disposal are not equal to the task. But, on the other hand, in its own sphere and working with its own particular abstractions, science is quite competent to reach its own results in its own way, and this without any necessary correction on the part of metaphysics.
It will be perceived that the period of groping for the concrete causes of things gave place to one in which the synthesis of causes provided an explanation of causality. The concept of the efficient cause--not of the causal nexus and interaction as a whole--was, in the next stage, submitted to a critical analysis resulting in scepticism, then rehabilitated either on idealistic or mechanical lines. But the critical analysis, though it certainly led indirectly to both these later views as to causality, was answered, by the appeal to "common sense", in a way that, but for one missing factor, would probably have turned the current of philosophic thought back to Scholasticism and the Aristotelean doctrine, as the only one providing a satisfactory account, either of the action of what we call causes and the production of effects in the world, or of the true origin of the idea of necessary causality. For the theory of Aristotle and the Schoolmen can lay claim, most truly, to a character of common sense. It is based upon the observation, by the senses, of individual cases of causal action in the phenomenal world. So far it is no more than in agreement with the common experience of mankind. But, beyond this, it provides a suitable account of the manner in which an observation of individual cases can become an intellectual concept. This it does in its theory of the origin of ideas. In this point, then, the Scholastic system of philosophy can be represented as in full accord with, and built out of, the common judgments of mankind. It parts company with this only in requiring clearer evidence, using stricter analysis and sharper criticism. Also, it proceeds farther, though still along the lines traced by common sense, in its analyses and syntheses, until it has presented natural knowledge as a complete and co-ordinate whole.
The fact, already alluded to, that several of the systems given to the world, even after Hume's criticism, have much in common with, yet lack the conclusive and convincing force of, the Scholastic system on this issue, would seem to argue in favour of the claim of the latter to common sense or naturalness. As a metaphysical theory, it has the merit of being straightforward, clear, and consistent; and it accounts for that for which it professes to account without ambiguity or circumlocution. That, as a matter of history, modern speculation on this point did not return, confirmed and justified, to the earlier lines, after the criticism of Hume, is probably due, in the main, to the fact that the full concept of causality had been more or less lost sight of during the period preceding him. His criticism was aimed at the possibility of a knowledge of causal efficiency; and without an adequate theory of cognition, as well as a proper grasp of the relationships between efficient cause and effect in the process of becoming, the idea of efficiency, or power, is indeed inexplicable. Thus, while in the idealistic theories the attempt is made to restate the problem on a new basis, and solve it by reference to the manifestation, in one or another form, of Spirit, modern science pursues its own course and limits itself to the investigation of purely scientific conditions. Neither the one nor the other, properly speaking, raises the question as to the true and immediate causes of the qualities or essences of entities, for both have abandoned that standpoint from which alone the problem, in this sense, is envisaged.
Cause, in law, embraces any action, suit, or other original proceeding, between a plaintiff and a defendant. A cause of action is the entire set of facts that give rise to an enforceable claim. It includes the right of action; but the right does not necessarily include the cause. Thus, by lapse of time, a cause may cease to be actionable; or by legal enactment, as in the case of a solicitor, who cannot sue for his bill of costs until one month after its delivery. Until the expiry of the time there is no cause of action.
APA citation. (1908). Cause. In The Catholic Encyclopedia. New York: Robert Appleton Company. http://www.newadvent.org/cathen/03459a.htm
MLA citation. "Cause." The Catholic Encyclopedia. Vol. 3. New York: Robert Appleton Company, 1908. <http://www.newadvent.org/cathen/03459a.htm>.
Transcription. This article was transcribed for New Advent by Rick McCarty.
Ecclesiastical approbation. Nihil Obstat. November 1, 1908. Remy Lafort, S.T.D., Censor. Imprimatur. +John Cardinal Farley, Archbishop of New York.
Contact information. The editor of New Advent is Kevin Knight. My email address is feedback732 at newadvent.org. (To help fight spam, this address might change occasionally.) Regrettably, I can't reply to every letter, but I greatly appreciate your feedback — especially notifications about typographical errors and inappropriate ads.