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  • CAUSE IN GREEK PHILOSOPHY The Pre-Socratics, Plato, Aristotle
  • scholastic ">THE SCHOLASTIC ANALYSIS OF CAUSATION Material Cause, Formal Cause, Efficient Cause, Final Cause
  • CAUSATION IN MODERN THOUGHTBacon, Descartes, Hume, Reid, Kant
  • LATER SPECULATIONS Hegel and Schopenhauer, Cause in Science, Common Sense, law "> Cause in Law

(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.


The Pre-Socratics

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:

  • matter, húle--tò hex oû gínetaí tí enupárchontos
  • form, morphé, eîdos--ho lógos ho toú ti ên eînai--
  • moving, or efficient cause, tò kinetikó--hóthen he archè tês metabolés he próte--
  • final cause, tò télos--tò hoû héneka (Cf. Physics, II, iii.)
These are severally related in various ways. It is in the declaration of this relationship that the notion and explanation of causality is to be found. The material cause, that out of which the principiate, or effect, is made or caused, is conceived as an indeterminate potentiality. It is determined to a definite substantial essence by the formal cause. This, in turn, is conceived as an actuality specifying the material potentiality. Formal causes are the changeless essences of things in themselves, permanent in them amid the flux of accidental modifications, yet by actual union with the material cause determining this to the concrete individual ; and not, like the ideas of Plato, separated from it. They are, under the action of the moving, or efficient, cause, the accomplishment of the determinability of matter. The moving, or efficient, cause, which, as will be seen later, is that which has come to be chiefly regarded as the true cause, and that round which most controversy has arisen, is, in this fourfold division of causes, that one by the operation or agency of which the effect is brought into being; i.e. by the operation of which the formal cause of the effect is induced in the material. Lastly, the final cause is that principle on account of which the efficient cause moves towards the production of its effect. It is the effect itself formally considered as the term of the intention of the agent, or efficient cause. Neither Aristotle nor Plato is very clear as to the precise sense in which the final cause is to be understood. The Aristotelean phrase is loose enough to cover the two meanings: i.e., the end considered as the object desired, and the end considered as the desire of the object. Aristotle perceives and teaches that the end is frequently identified with the form, and that this is also frequently identified in species with the moving cause; for man, as he says in the example that he gives, begets man. It does not, however, follow that all moving causes are always identified, even in species, with their effects. Indeed, Aristotle teaches that this is not the case. He holds that the world is eternal ; but, in virtue of his fundamental principle that no potentiality can precede actuality, he makes it a participative eternity. Hence the material and the formal causes that together go to make up the world are created, or more properly, eternally concreated. From this fundamental principle of the priority of actuality over potentiality, Aristotle proves also the fact of the existence of God as the first moving cause. As each effect of a process is now to be reckoned an actuality that was before no more than potential, and postulates a moving cause in order that it should have come into being as the term of a motion, so all things in the world, taken together, necessitate an absolutely first cause of the same nature. This first moving cause must, on Aristotle's principle, be an absolute actuality, since, were it not entirely in act, it could not be the moving cause of all things nor keep them eternally in motion. Similarly, it must be pure form, or noûs, with no admixture of matter, since this would import a limitation of its actuality. Thus did Aristotle raise and answer the question of causality, dividing causes into four classes, and indicating the nature of the causal influx with which each contributes towards the production of their common effect. For, according to this theory, all the four causes, taken together, are really the cause of any given physical effect.


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 thing that is changed;
  • the term, or manner of being, or essence, that is induced in that which is changed;
  • the active agent that produces the change, or accomplishes the existence of the new term, manner of being, or essence ; and
  • the motive, or reason why this latter acts.
  • There is also, though it cannot be reckoned as a cause, the terminus a quo, or the original determinative of the thing changed, which passes out of being with the advent of the newly induced term. These four necessary things, since they produce the final result by a mutual action and interaction, in which they give being to it considered as result, are its causes. They are to be discovered, moreover, wherever and whenever any change takes place, not only in substantial, but also in accidental, changes, or mere changes of qualities." Consider the two cases, the one of accidental, the other of substantial, change. A cube of wax is moulded by the hand into a sphere. The wax, as permanent substratum of the change of figure, is considered to be the matter, or material cause. The spherical figure supervening upon that of the cubical, is the induced formal cause. The moulder, or fashioner of the sphere, is the efficient cause. The final cause is to be sought for in the intention of the moulder. The substance of the wax remains throughout the entire process of the moulding. It is affected only accidentally by the operation. Consequently the example is one of accidental change, and gives us no more than an accidental formal cause. But in cases of substantial change, such as, for example, the electrolysis of water, the induced formal cause is a substantial one; and, moreover, since the substance of the water does not remain after the change has taken place, the material cause cannot be other than a subject, or permanent substratum, that is neither water nor oxygen and hydrogen taken together. In such a case, it is called primordial, or first matter, and is conceived as being a subject potential to information by any and all formal causes. It is a potentiality, but, as a permanent substratum, or determinable entity, is capable of receiving new substantial determinations in the place of that which actually denominates it. It cannot exist alone, but exists only as informed, or actuated by a formal cause. It is not eternal, but created, or, more properly, concreated with substantial form. Material Cause

    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.

    Formal Cause

    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).

    Efficient Cause

    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 :

  • Whatever exists in nature is either a cause or an effect (Contra Gent., III, cvii).
  • No entity can be its own cause (op. cit., II, xxi).
  • There is no effect without a cause.
  • Given the cause, the effect follows; the cause removed, the effect ceases. This axiom is to be understood of causes efficient in act, and of effects related to them not only in becoming but also in being (op. cit., II, xxxv).
  • An effect requires a proportionate cause. This axiom is to be understood in the sense that actual effects respond to actual causes, particular effects to particular causes, etc. (op. cit., II, xxi).
  • The cause is by nature prior to its effect. Priority is not necessarily understood here as relating to time. (Op. cit., II, xxi; Summa theol. III:62:6 ; "De potentiâ", Q. iii, a. xiii; "De veritate", Q. xxviii, a. vii.)
  • The perfection of the effect pre-exists in its cause (formally, virtually, or eminently). (Cf. Summa theol. I:6:2. )
  • Whatever is the cause of a cause (precisely as cause) is the cause also of its effect. This axiom enunciates a truth with regard to series of connected causes formally acting by their nature. (Cf. Summa Theol. I:45:5. )
  • The first cause (in any order of causes dependent one on the other) contributes more to the production of the effect than the secondary cause. (Cf. De causis, in cap.) Arguments, besides that given above, for the establishing of the fact of efficient causality in the physical world are to be found in the "Contra Gentiles ", III, lxix.
  • It may be pointed out, in anticipation of the conception of purely mechanical, or dynamical, causation to be referred to later on, that in this system causation is not merely taken to mean an impulse, or change, in motion. The theory advanced is one to account for change of any kind, and, by a profound analysis, to reach the causes upon which things depend for their becoming and their actual beings. Final Cause

    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 produc

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