Chapter XLII: Section D: Methodology of Science (2)

After this brief survey, if we look back over the road we have come, we observe the following general facts. In every case the development of a science consists in the formation of concepts by certain abstractions from experience, and setting of these concepts in relation with each other so that a systematical control of certain sides of our experience is made possible. These relations, according to their generality and reliability, are called rules or laws. A law is the more important the more it definitely expresses concerning the greatest possible number of things, and the more accurately, therefore, it enables us to predict the future. Every law rests upon an incomplete induction, and is therefore subject to modification by experience. From this there results a double process in the development of science.

First, the actual conditions are investigated to find out whether, besides those already known, new rules or laws, that is, constant relations between individual peculiarities, cannot be discovered between them. This is the inductive process, and the induction is always an incomplete one on account of the limitlessness of all possible experience.

Immediately the relationship found inductively is applied to cases which have not yet been investigated. Especially such cases are investigated as result from a combination of several inductive laws. If these are perfectly certain, and the combination is also properly made, the result has claim to unconditional validity. This is the limit which all sciences are striving to reach. It has almost been reached in the simpler sciences: in mathematics and in certain parts of mechanics. This is called the deductive process.

In the actual working of every science the two methods of investigation are continually changing. The best means of finding new successful inductions is in the making of a deduction on a very insufficient basis, perhaps, and subsequently testing it in experience. Sometimes the elements of his deductions do not come into the investigator's consciousness; in such cases we speak of scientific instinct. On the other hand we have much evidence from great mathematicians that they were accustomed to find their general laws by the method of induction, by trying and considering single cases; and that the deductive derivation from other known laws is an independent operation which sometimes does not succeed until much later. Indeed there is to-day a number of mathematical propositions which have not yet reached the second stage and therefore have at present a purely inductive empirical character. The proportion of such laws in science increases very quickly with the rise in the scale (page 339).

Another peculiarity which may be mentioned here is that in the scale all previous sciences have the character of applied sciences (page 341) with reference to those which follow, since they are everywhere necessary in the technique of the latter, yet do not serve to increase their own field but are merely auxiliaries to the latter.

If we ask finally what influence upon the shaping of the future such investigations as those which have been sketched in outline above can have, the following can be said. Up till now it has been considered a completely uncontrollable event whether and where a great and influential man of science has developed. It is obvious that such a man is among the most costly treasures which a people (and, indeed, humanity) can possess. The conscious and regular breeding of such rarities has not been considered possible. While this is still the case for the very exceptional genius, we see in the countries of the older civilization, especially in Germany at present, a system of education in vogue in the universities by which a regular harvest of young scientific men is gained who not only have a mastery of knowledge handed down, but also of the technique of discovery. Thereby the growth of science is made certain and regular, and its pursuit is raised to a higher plane. These results were formerly attained chiefly by empirically and oftentimes by accidental processes. It is a task of scientific theory to make this activity also regular and systematic, so that success is no more dependent solely upon a special capacity for the founding of a "school" but can also be attained by less original minds. By the mastery of methods the way to considerably higher performances than he could otherwise attain will be open for the exceptionally gifted.

THE CONTENT AND VALIDITY OF THE CAUSAL LAW

BY BENNO ERDMANN

(_Translated from the German by Professor Walter T. Marvin, Western Reserve University_)

[Benno Erdmann, Professor of Philosophy, University of Bonn,
since 1898. b. October 5, 1851, Glogau in Schlesien,
Germany. Ph.D.; Privy Councilor. Academical Lecturer,
Berlin, 1876- ; Special Professor, Kiel, 1878-79; Regular
Professor, _ibid._ 1879-84; _ibid._ Breslau, 1884-90;
_ibid._ Halle, 1890-98. Member various scientific and
learned societies. Author of _The Axioms of Geometry_;
_Kant's Criticism_; _Logic_; _Psychological Researches on
Reading_ (together with Prof. Ramon Dodge); _The Psychology
of the Child and the School_; _Historical Researches an
Kant's Prolegomena_, and many other works and papers in
Philosophy.]

We have learned to regard the real, which we endeavor to apprehend scientifically in universally valid judgments, as a whole that is connected continuously in time and in space and by causation, and that is accordingly continuously self-evolving. This continuity of connection has the following result, namely, every attempt to classify the sum total of the sciences on the basis of the difference of their objects leads merely to representative types, that is, to species which glide into one another. We find no gaps by means of which we can separate sharply physics and chemistry, botany and zoölogy, political and economic history and the histories of art and religion, or, again, history, philology, and the study of the prehistoric.

As are the objects, so also are the methods of science. They are separable one from another only through a division into representative types; for the variety of these methods is dependent upon the variety of the objects of our knowledge, and is, at the same time, determined by the difference between the manifold forms of our thought, itself a part of the real, with its elements also gliding into One another.[4]

[Footnote 4: Cf. the author's "Theorie der
Typeneinteilungen," _Philosophische Monatshefte_, vol. xxx,
Berlin, 1894.]

The threads which join the general methodology of scientific thought with neighboring fields of knowledge run in two main directions. In the one direction they make up a closely packed cable, whereas in the other their course diverges into all the dimensions of scientific thought. That is to say, first, methodology has its roots in logic, in the narrower sense, namely, in the science of the elementary forms of our thought which enter into the make-up of all scientific methods. Secondly, methodology has its source in the methods themselves which actually, and therefore technically, develop in the various fields of our knowledge out of the problems peculiar to those fields.

It is the office of scientific thought to interpret validly the objects that are presented to us in outer and inner perception, and that can be derived from both these sources. We accomplish this interpretation entirely through judgments and combinations of judgments of manifold sorts. The concepts, which the older logic regarded as the true elementary forms of our thinking, are only certain selected types of judgment, such stereotyped judgments as those which make up definitions and classifications, and which appear independent and fundamental because their subject-matter, that is, their intension or extension, is connected through the act of naming with certain words. Scientific methods, then, are the ways and means by which our thought can accomplish and set forth, in accordance with its ideal, this universally valid interpretation.

There belongs, accordingly, to methodology a list of problems which we can divide, to be sure only _in abstracto_, into three separate groups. First, methodology has to analyze the methods which have been technically developed in the different fields of knowledge into the elementary forms of our thinking from which they have been built up. Next to this work of _analyzing_, there comes a second task which may be called a _normative_ one; for it follows that we must set forth and deduce systematically from their sources the nature of these manifold elements, their resulting connection, and their validity. To these two offices must be added a third that we may call _a potiori_ a _synthetic_ one; for finally we must reconstruct out of the elements of our thinking, as revealed by analysis, the methods belonging to the different fields of knowledge and also determine their different scope and validity.

The beginning of another conception of the office of methodology can be found in those thoughts which have become significant, especially in Leibnitz's fragments and drafts of a _calculus ratiocinator_ or a _spécieuse générale_. The foregoing discussion has set aside all hope that these beginnings and their recent development may give, of the possibility of constructing the manifold possible methods _a priori_, that is, before or independent of experience. However, it remains entirely undecided, as it should in this our preliminary account of the office of general methodology, whether or not all methods of our scientific thought will prove to be ultimately but branches of one and the same universal method, a thought contained in the undertakings just referred to. Although modern empiricism, affiliated as it is with natural science, tends to answer this question in the affirmative even more definitely and dogmatically than any type of the older rationalism, still the question is one that can be decided only in the course of methodological research.

The conception of a methodology of scientific thought can be said to be almost as old as scientific thought itself; for it is already contained essentially, though undifferentiated, in the Socratic challenge of knowledge. None the less, the history of methodology, as the history of every other science, went through the course of which Kant has given a classical description. "No one attempts to construct a science unless he can base it on some idea; but in the elaboration of it the schema, nay, even the definition which he gives in the beginning of his science, corresponds very seldom to his idea, which, like a germ, lies hidden in the reason, and all the parts of which are still enveloped and hardly distinguishable even under microscopical observation."[5]

[Footnote 5: Kant, _Kr. d. r. V._, 2d ed., p. 862.]

We are indebted to the Greek, and especially to the Platonic-Aristotelian philosophy for important contributions to the understanding of the deductive method of mathematical thought. It was precisely this trend of philosophic endeavor which, though furnishing for the most part the foundation of methodological doctrine well on into the seventeenth century, offered no means of differentiating the methods that are authoritative for our knowledge of facts. What Socrates was perhaps the first to call "induction," is essentially different, as regards its source and aim, from the inductive methods that direct our research in natural and mental science. For it is into these two fields that we have to divide the totality of the sciences of facts, the material sciences, let us call them, in opposition to the formal or mathematical sciences,--that is, if we are to do justice to the difference between sense and self perception, or "outer" and "inner" perception.

Two closely connected forces especially led astray the methodological opinions regarding the material sciences till the end of the eighteenth century, and in part until the beginning of the nineteenth century. We refer, in the first place, to that direction of thought which gives us the right to characterize the Platonic-Aristotelian philosophy as a "concept philosophy;" namely, the circumstance that Aristotelian logic caused the "concept" to be set before the "judgment." In short, we refer to that tendency in thought which directs the attention not to the permanent in the world's occurrences, the uniform connections of events, but rather to the seemingly permanent in the things, their essential attributes or essences. Thus the concept philosophy, as a result of its tendency to hypostasize, finds in the abstract general concepts of things, the ideas, the eternal absolute reality that constitutes the foundation of things and is contained in them beside the accidental and changing properties.[6] Here we have at once the second force which inspired the ancient methodology. These ideas, like the fundamentally real, constitute that which ultimately alone acts in all the coming into existence and the going out of existence of the manifold things. In the Aristotelian theory of causation, this thought is made a principle; and we formulate only what is contained in it, when we say that, according to it, the efficient and at the same time final causes can be deduced through mere analysis from the essential content of the effects; that, in fact, the possible effects of every cause can be deduced from the content of its definition. The conceptual determination of the causal relation, and with it in principle the sum total of the methods in the material sciences, becomes a logical, analytical, and deductive one. These sciences remain entirely independent of the particular content of experience as this broadens, and so do also the methods under discussion.

[Footnote 6: According to Plato, it is true, the ideas are
separated from the sensible things; they must be thought in
a conceptual place, for the space of sense perception is to
be understood as non-being, matter. The things revealed to
sense, however, occupy a middle position between being and
non-being, so that they partake of the ideas. In this sense,
the statement made above holds also of the older view of the
concept philosophy.]

As a consequence, every essential difference between mathematical thought and the science of causes is done away with in favor of a rationalistic construction of the methods of material science. Accordingly, throughout the seventeenth century, the ideal of all scientific method becomes, not the inductive method that founded the new epoch of the science of to-day, but the deductive mathematical method applied to natural scientific research. The flourish of trumpets with which Francis Bacon hailed the onslaught of the inductive methods in the natural science of the time, helped in no way; for he failed to remodel the traditional, Aristotelian-Scholastic conception of cause, and, accordingly, failed to understand both the problem of induction and the meaning of the inductive methods of the day.[7] Descartes, Hobbes, Spinoza, and related thinkers develop their _mathesis universalis_ after the pattern of geometrical thinking. Leibnitz tries to adapt his _spécieuse générale_ to the thought of mathematical analysis. The old methodological conviction gains its clear-cut expression in Spinoza's doctrine: "_Aliquid efficitur ab aliqua re_" means "_aliquid sequitur ex ejus definitione_."

[Footnote 7: Cf. the articles on Francis Bacon by Chr.
Sigwart in the _Preussische Jahrbücher_, xii, 1863, and
xiii, 1864.]

The logically straight path is seldom the one taken in the course of the history of thought. The new formulation and solution of problems influence us first through their evident significance and consequences, not through the traditional presuppositions upon which they are founded. Thus, in the middle of the seventeenth century, when insight into the precise difference between mental and physical events gave rise to pressing need for its definite formulation, no question arose concerning the dogmatic presupposition of a purely logical (_analytisch_) relationship between cause and effect; but, on the contrary, this presupposition was then for the first time brought clearly before consciousness. It was necessary to take the roundabout way through occasionalism and the preëstablished harmony, including the latter's retreat to the omnipotence of God, before it was possible to miss the question of the validity of the presupposition that the connection between cause and effect is analytic and rational.

Among the leading thinkers of the period this problem was recognized as the cardinal problem of contemporaneous philosophy. It is further evidence how thoroughly established this problem must have been among the more deeply conceived problems of the time in the middle of the eighteenth century, that Hume and Kant were forced to face it, led on, seemingly independently of each other, and surely from quite different presuppositions and along entirely different ways. The historical evolution of that which from the beginning has seemed to philosophy the solving of her true problem has come to pass in a way not essentially different from that of the historical evolution in all other departments of human knowledge. Thus, in the last third of the seventeenth century, Newton and Leibnitz succeeded in setting forth the elements of the infinitesimal calculus; and, in the fifth decade of the nineteenth century, Robert Mayer, Helmholtz, and perhaps Joule, formulated the law of the conservation of energy. In one essential respect Hume and Kant are agreed in the solution of the new, and hence contemporaneously misunderstood, problem. Both realized that the connection between the various causes and effects is not a rational analytic, but an empirical synthetic one. However, the difference in their presuppositions as well as method caused this common result to make its appearance in very different light and surroundings. In Hume's empiricism the connection between cause and effect appears as the mere empirical result of association; whereas in Kant's rationalism this general relation between cause and effect becomes the fundamental condition of all possible experience, and is, as a consequence, independent of all experience. It rests, as a means of connecting our ideas, upon an inborn uniformity of our thought.

Thus the way was opened for a fundamental separation of the inductive material scientific from the deductive mathematical method. For Hume mathematics becomes the science of the relations of ideas, as opposed to the sciences of facts. For Kant philosophical knowledge is the knowledge of the reason arising from concepts, whereas the mathematical is that arising from the construction of concepts. The former, therefore, studies the particular only in the universal; the latter, the universal in the particular, nay, rather in the individual.

Both solutions of the new problem which in the eighteenth century supplant the old and seemingly self-evident presupposition, appear accordingly embedded in the opposition between the rationalistic and empiristic interpretation of the origin and validity of our knowledge, the same opposition that from antiquity runs through the historical development of philosophy in ever new digressions.

Even to-day the question regarding the meaning and the validity of the causal connection stands between these contrary directions of epistemological research; and the ways leading to its answer separate more sharply than ever before. It is therefore more pressing in our day than it was in earlier times to find a basis upon which we may build further epistemologically and therefore methodologically. The purpose of the present paper is to seek such a basis for the different methods employed in the sciences of facts.

* * * * *

As has already been said, the contents of our consciousness, which are given us immediately in outer and inner perception, constitute the raw material of the sciences of facts. From these various facts of perception we derive the judgments through which we predict, guide, and shape our future perception in the course of possible experience. These judgments exist in the form of reproductive ideational processes, which, if logically explicit, become _inductive inferences_ in the broader sense. These inferences may be said to be of two sorts, though fundamentally only two sides of one and the same process of thought; they are in part analogical inferences and in part _inductive inferences in the narrower sense_. The former infers from the particular in a present perception, _which in previous perceptions was uniformly connected with other particular contents of perception_, to a particular that resembles _those other contents of perception_. In short, they are inferences from a particular to a particular. After the manner of such inferences we logically formulate, for example, the reproductive processes, whose conclusions run: "This man whom I see before me, is attentive, feels pain, will die;" "this meteor will prove to have a chemical composition similar to known meteors, and also to have corresponding changes on its surface as the result of its rapid passage through our atmosphere." The inductive inferences in the narrower sense argue, on the contrary, from the perceptions of a series of uniform phenomena to a universal, which includes the given and likewise all possible cases, in which a member of the particular content of the earlier perceptions is presupposed as given. In short, they are conclusions from a particular to a universal that is more extensive than the sum of the given particulars. For example: "All men have minds, will die;" "all meteoric stones will prove to have this chemical composition and those changes of surface."

There is no controversy regarding the inner similarity of both these types of inference or regarding their outward structure; or, again, regarding their outward difference from the deductive inferences, which proceed not from a particular to a particular or general, but from a general to a particular.

There is, however, difference of opinion regarding their inner structure and their inner relation to the deductive inferences. Both questions depend upon the decision regarding the meaning and validity of the causal relation. The contending parties are recruited essentially from the positions of traditional empiricism and rationalism and from their modern offshoots.

We maintain first of all:

1. The _presupposition_ of all inductive inferences, from now on to be taken in their more general sense, is, that the contents of perception are given to us _uniformly_ in repeated perceptions, that is, in uniform components and uniform relations.

2. The _condition_ of the validity of the inductive inferences lies in the thoughts that _the same causes will be present_ in the unobserved realities as in the observed ones, and that _these same causes will bring forth the same effects_.

3. The _conclusions_ of all inductive inferences have, logically speaking, purely _problematic_ validity, that is, their contradictory opposite remains equally thinkable. They are, accurately expressed, merely _hypotheses_, whose validity needs verification through future experience.

The first-mentioned _presupposition_ of inductive inference must not be misunderstood. The paradox that nothing really repeats itself, that each stage in nature's process comes but once, is just as much and just as little justified as the assertion, everything has already existed. It does not deny the fact that we can discriminate in the contents of our perceptions the uniformities of their components and relations, in short, that similar elements are present in these ever new complexes. This fact makes it possible that our manifold perceptions combine to make up one continuous experience. Even our paradox presupposes that the different contents of our perceptions are comparable with one another, and reveal accordingly some sort of common nature. All this is not only a matter of course for empiricism, which founds the whole constitution of our knowledge upon habits, but must also be granted by every rationalistic interpretation of the structure of knowledge. Every one that is well informed knows that what we ordinarily refer to as facts already includes a theory regarding them. Kant judges in this matter precisely as Hume did before him and Stuart Mill after him. "If cinnabar were sometimes red and sometimes black, sometimes light and sometimes heavy, if a man could be changed now into this, now into another animal shape, if on the longest day the fields were sometimes covered with fruit, sometimes with ice and snow, the faculty of my empirical imagination would never be in a position, when representing red color, to think of heavy cinnabar."[8]

[Footnote 8: Kant, _Kr. d. r. V._, 1st ed., pp. 100 f.]

The assumption that in recurring perceptions similar elements of content, as well as of relation, are given, is a necessary condition of the possibility of experience itself, and accordingly of all those processes of thought which lead us, under the guidance of previous perceptions, from the contents of one given perception to the contents of possible perceptions.

A tradition from Hume down has accustomed us to associate the relation of cause and effect not so much with the uniformity of coexistence as with the uniformity of sequence. Let us for the present keep to this tradition. Its first corollary is that the relation of cause and effect is to be sought in the uninterrupted flow and connection of events and changes. The cause becomes the uniformly preceding event, the constant _antecedens_, the effect the uniformly following, the constant _consequens_, in the course of the changes that are presented to consciousness as a result of foregoing changes in our sensorium.

According to this tradition that we have taken as our point of departure, the uniformity of the sequence of events is a necessary presupposition of the relation between cause and effect. This uniformity is given us as an element of our experience; for we actually find uniform successions in the course of the changing contents of perception. Further, as all our perceptions are in the first instance sense perceptions, we may call them the sensory presupposition of the possibility of the causal relation.

In this presupposition, however, there is much more involved than the name just chosen would indicate. The uniformity of sequence lies, as we saw, not in the contents of perception as such, which are immediately given to us. It arises rather through the fact that, in the course of repeated perceptions, we apprehend through abstraction the uniformities of their temporal relation. Moreover, there lie in the repeated perceptions not only uniformities of sequence, but also uniformities of the qualitative content of the successive events themselves, and these uniformities also must be apprehended through abstraction. Thus these uniform contents of perception make up series of the following form:

_a_1 --> _b_1
_a_2 --> _b_2
" "
" "
" "
_a_n --> _b_n

The presupposition of the possibility of the causal relations includes, therefore, more than mere perceptive elements. It involves the relation of different, if you will, of peculiar contents of perception, by virtue of which we recognize _a_2 --> _b_2 ... _a_n --> _b_n as events that resemble one another and the event _a_1 --> _b_1 qualitatively as well as in their sequence. There are accordingly involved in our presupposition _reproductive_ elements which indicate the action of memory. In order that I may in the act of perceiving _a_3 --> _b_3 apprehend the uniformity of this present content with that of _a_2 --> _b_2 and _a_1 --> _b_1, these earlier perceptions must in some way, perhaps through memory,[9] be revived with the present perception.

[Footnote 9: It is not our present concern to ascertain how
this actually happens. The psychological presuppositions of
the present paper are contained in the theory of
reproduction that I have worked out in connection with the
psychology of speech in the articles on "Die psychologischen
Grundlagen der Beziehungen zwischen Sprechen und Denken,"
_Archiv für systematische Philosophie_, II, III, und VII;
cf. note 1, page 151.]

In this reproduction there is still a further element, which can be separated, to be sure only _in abstracto_, from the one just pointed out. The present revived content, even if it is given in memory as an independent mental state, is essentially different from the original perception. It differs in all the modifications in which the memory of lightning and thunder could differ from the perception of their successive occurrence, or, again, the memory of a pain and the resulting disturbance of attention could differ from the corresponding original experience. However, as memory, the revived experience presents itself as a picture of that which has been previously perceived. Especially is this the case in memory properly so called, where the peculiar space and time relations individualize the revived experience. If we give to this identifying element in the associative process a logical expression, we shall have to say that there is involved in revival, and especially in memory, an awareness that the present ideas recall the same content that was previously given us in perception. To be sure, the revival of the content of previous perceptions does not have to produce ideas, let alone memories. Rapid, transitory, or habitual revivals, stimulated by associative processes, can remain unconscious, that is, they need not appear as ideas or states of consciousness. Stimulation takes place, but consciousness does not arise, provided we mean by the term "consciousness" the genus of our thoughts, feelings, and volitions. None the less it must not be forgotten that this awareness of the essential identity of the present revived content with that of the previous perception can be brought about in every such case of reproduction. How all this takes place is not our present problem.

We can apply to this second element in the reproductive process, which we have found to be essential to the causal relation, a Kantian term, "Recognition." This term, however, is to be taken only in the sense called for by the foregoing statements; for the rationalistic presuppositions and consequences which mark Kant's "Synthesis of Recognition" are far removed from the present line of thought.

We may, then, sum up our results as follows: In the presupposition of a uniform sequence of events, which we have accepted from tradition as the necessary condition of the possibility of the causal relation, there lies the thought that the contents of perception given us through repeated sense stimulation are related to one another through a reproductive recognition.

The assumption of such reproductive recognition is not justified merely in the cases so far considered. It is already necessary in the course of the individual perceptions _a_ and _b_, and hence in the apprehension of an occurrence. It makes the sequence itself in which _a_ and _b_ are joined possible; for in order to apprehend _b_ as following upon _a_, in case the perception of _a_ has not persisted in its original form, _a_ must be as far revived and recognized upon _b_'s entrance into the field of perception as it has itself passed out of that field. Otherwise, instead of _b_ following upon _a_ and being related to _a_, there would be only the relationless change from _a_ to _b_. This holds generally and not merely in the cases where the perception of _a_ has disappeared before that of _b_ begins, for example, in the case of lightning and thunder, or where it has in part disappeared, for example, in the throwing of a stone.

We have represented _a_ as an event or change, in order that uniform sequences of events may alone come into consideration as the presupposition of the causal relation. But every event has its course in time, and is accordingly divisible into many, ultimately into infinitely many, shorter events. Now if _b_ comes only an infinitely short interval later than _a_, and by hypothesis it must come later than _a_, then a corresponding part of _a_ must have disappeared by the time _b_ appears. But the infinitesimal part of a perception is just as much out of all consideration as would be an infinitely long perception; all which only goes to show that we have to substitute intervals of finite length in place of this purely conceptual analysis of a continuous time interval. This leaves the foregoing discussion as it stands. If _b_ follows _a_ after a perceptible finite interval, then the flow or development of _a_ by the time of _b_'s appearance must have covered a course corresponding to that interval; and all this is true even though the earlier stages of _a_ remain unchanged throughout the interval preceding _b_'s appearance. The present instant of flow is distinct from the one that has passed, even though it takes place in precisely the same way. The former, not the latter, gives the basis of relation which is here required, and therefore the former must be reproduced and recognized. This thought also is included in the foregoing summary of what critical analysis shows to be involved in the presupposition of a uniform sequence.

In all this we have already abandoned the field of mere perception which gave us the point of departure for our analysis of uniform sequence. We may call the changing course of perception only in the narrower meaning the sensory presupposition of the causal relation. In order that these changing contents of perception may be known as like one another, as following one another, and as following one another uniformly, they must be related to one another through a recognitive reproduction.

Our critical analysis of uniform sequence is, however, not yet complete. To relate to one another the contents of two ideas always requires a process at once of identifying and of differentiating, which makes these contents members of the relation, and which accordingly presupposes that our attention has been directed to each of the two members as well as to the relation itself--in the present case, to the sequence. Here we come to another essential point. We should apply the name "thought" to every ideational process in which attention is directed to the elements of the mental content and which leads us to identify with one another, or to differentiate from one another, the members of this content.[10] The act of relating, which knows two events as similar, as following one another, indeed, as following one another uniformly, is therefore so far from being a sensation that it must be claimed to be an act of thinking. The uniformity of sequence of _a_ and _b_ is therefore an act of relating on the part of our thought, so far as this becomes possible solely through the fact that we at one and the same time identify with one another and differentiate from one another _a_ as cause and _b_ as effect. We say "at one and the same time," because the terms identifying and differentiating are correlatives which denote two different and opposing sides of one and the same ideational process viewed logically. Accordingly, there is here on need of emphasizing that the act of relating, which enables us to think _a_ as cause and _b_ as effect, is an act of thought also, because it presupposes on our part an act of naming which raises it to being a component of our formulated and discursive thought. We therefore _think a_ as cause and _b_ as effect in that we apprehend the former as uniform _antecedens_ and the latter as uniform _consequens_.

[Footnote 10: Cf. the author's "Umrisse zur Psychologie des
Denkens," in _Philosophische Abhandlungen Chr. Sigwart ...
gewidmet_, Tübingen, 1900.]

* * * * *

Have we not the right, after the foregoing analysis, to interpret the uniform sequence of events solely as the _necessary_ presupposition of the causal relation? Is it not at the same time the _adequate_ presupposition? Yes, is it not the causal relation itself? As we know, empiricism since Hume has answered the last question in the affirmative, and rationalism since Kant has answered it in the negative.

We, too, have seemingly followed in our discussion the course of empiricism. At least, I find nothing in that discussion which a consistent empiricist might not be willing to concede; that is, if he is ready to set aside the psychological investigation of the actual processes which we here presuppose and make room for a critical analysis of the content of the relation of cause and effect.[11] However, the decision of the question, whether or not empiricism can determine exhaustively the content that we think in the causal relation, depends upon other considerations than those which we have until now been called upon to undertake. We have so far only made clear what every critical analysis of the causal relation has to concede to empiricism. In reality the empiristic hypothesis is inadequate. To be sure, the proof of this inadequacy is not to be taken from the obvious argument which Reid raised against the empiricism of Hume, and which compelled Stuart Mill in his criticism of that attack[12] to abandon his empiristic position at this point. No doubt the conclusion to which we also have come for the time being, goes much too far, the conclusion that the cause is nothing but the uniform _antecedens_ and the effect merely the uniform _consequens_. Were it true, as we have hitherto assumed, that every uniformly preceding event is to be regarded as cause and every uniformly following event as effect, then day must be looked upon as cause of night and night as cause of day.

[Footnote 11: The difference between the two points of view
can be made clearer by an illustration. The case that we
shall analyze is the dread of coming into contact with fire.
The psychological analysis of this case has to make clear
the mental content of the dread and its causes. Such dread
becomes possible only when we are aware of the burning that
results from contact with fire. We could have learned to be
aware of this either immediately through our own experience,
or mediately through the communication of others'
experience. In both cases it is a matter of one or repeated
experiences. In all cases the effects of earlier experiences
equal association and recall, which, in turn, result in
recognition. The recognition explaining the case under
discussion arises thus. The present stimuli of visual
perception arouse the retained impressions of previous
visual perceptions of fire and give rise to the present
perception (apperception) by fusing with them. By a process
of interweaving, associations are joined to this perception.
The apperceptively revived elements which lie at the basis
of the content of the perception are interwoven by
association with memory elements that retain the additional
contents of previous perceptions of fire, viz., the burning,
or, again, are interwoven with the memory elements of the
communications regarding such burning. By means of this
interweaving, the stimulation of the apperceptive element
transmits itself to the remaining elements of the
association complex. The character of the association is
different under different conditions. If it be founded only
upon one experience, then there can arise a memory or a
recall, in the wider sense, of the foregoing content of the
perception and feeling at the time of the burning, or,
again, there can arise a revival wherein the stimulated
elements of retention remain unconscious. Again, the words
of the mother tongue that denote the previous mental
content, and which likewise belong to the association
complex (the apperceiving mass, in the wider sense), can be
excited in one of these three forms and in addition as
abstract verbal ideas. Each one of these forms of verbal
discharge can lead to the innervations of the muscles
involved in speech, which bring about some sort of oral
expression of judgment. Each of these verbal reproductions
can be connected with each of the foregoing sensory
(_sachlichen_) revivals. Secondly, if the association be
founded upon repeated perceptions on the part of the person
himself, then all the afore-mentioned possibilities of
reproduction become more complicated, and, in addition, the
mental revivals contain, more or less, only the common
elements of the previous perceptions, _i. e._, reappear in
the form of abstract ideas or their corresponding
unconscious modifications. In the third case the association
is founded upon a communication of others' experience. For
the sake of simplicity, let this case be confined to the
following instance. The communication consisted in the
assertion: "All fire will burn upon contact." Moreover, this
judgment was expressed upon occasion of imminent danger of
burning. There can then arise, as is perhaps evident, all
the possibilities mentioned in the second case, only that
here there will be a stronger tendency toward verbal
reproduction and the sensory reproduction will be less
fixed.

In the first two cases there was connected with the
perception of the burning an intense feeling of pain. In the
third the idea of such pain added itself to the visual
perception of the moment. The associated elements of the
earlier mental contents belong likewise to the apperceiving
mass excited at the moment, in fact to that part of it
excited by means of association processes, or, as we can
again say, depending upon the point from which we take our
view, the associative or apperceptive completion of the
content of present perception. If these pain elements are
revived as memories, _i. e._, as elements in consciousness,
they give rise to a new disagreeable feeling, which is
referred to the possible coming sensation of burning. If the
mental modifications corresponding to these pain elements
remain unconscious, as is often possible, there arises none
the less the same result as regards our feeling, only with
less intensity. This feeling tone we call the dread.

As a result of the sum total of the revivals actual and
possible, there is finally produced, according to the
particular circumstances, either a motor reaction or an
inhibitant of such reaction. Both innervations can take
place involuntarily or voluntarily.

The critical analysis of the fact that we dread contact with
fire, even has another purpose and accordingly proceeds on
other lines. It must make clear under what presuppositions
the foresight that lies at the basis of such dread is valid
for future experience. It must then formulate the actual
process of revival that constitutes the foundation of this
feeling as a series of judgments, from which the meaning and
interconnection of the several judgments will become clear.
Thus the critical analysis must give a logical presentation
of the apperceptive and associative processes of revival.

For this purpose the three cases of the psychological
analysis reduce themselves to two: viz., first, to the case
in which an immediate experience forms the basis, and
secondly, to that in which a variety of similar mediately or
immediately communicated experiences form such basis.

In the first of these logically differentiated cases, the
transformation into the speech of formulated thought leads
to the following inference from analogy:

Fire A burned.
Fire B is similar to fire A.
----------------------------
Fire B will burn.

In the second case there arises a syllogism of some such
form as:

All fire causes burning upon contact.
This present phenomenon is fire.
--------------------------------------------------------
This present phenomenon will cause burning upon contact.

Both premises of this syllogism are inductive inferences,
whose implicit meaning becomes clear when we formulate as
follows:

All heretofore investigated instances of fire have burned,
therefore all fire burns.
The present phenomenon manifests some properties of fire,
will consequently have all the properties thereof.
---------------------------------------------------------
The present phenomenon will, in case of contact, cause burning.

The first syllogism goes from the particular to the
particular. The second proves itself to be (contrary to the
analysis of Stuart Mill) an inference that leads from the
general to the particular. For the conclusion is the
particular of the second parts of the major and minor
premises; and these second parts of the premises are
inferred from their first parts in the two possible ways of
inductive inference. The latter do not contain the case
referred to in the conclusion, but set forth the conditions
of carrying a result of previous experience over to a new
case with inductive probability, in other words, the
conditions of making past experience a means of foreseeing
future experience. It would be superfluous to give here the
symbols of the two forms of inductive inference.

We remain within the bounds of logical analysis, if we state
under what conditions conclusions follow necessarily from
their premises, viz., the conclusions of arguments from
analogy and of syllogisms in the narrower sense, as well as
those of the foregoing inductive arguments. For the
inference from analogy and the two forms of inductive
inference, these conditions are the presuppositions already
set forth in the text of the present paper, that in the as
yet unobserved portion of reality the like causes will be
found and they will give rise to like effects. For the
syllogism they are the thought that the predicate of a
predicate is the (mediate) predicate of the subject. Only
the further analysis of these presuppositions, which is
undertaken in the text, leads to critical considerations in
the narrower sense.]

[Footnote 12: _A System of Logic, Ratiocinative and
Inductive_, bk. III, ch. v, § 6.]

Empiricism can, however, meet this objection without giving up its position; in fact, it can employ the objection as an argument in its favor; for this objection affects only the manifestly imperfect formulation of the doctrine, not the essential arguments.

It should have been pointed out again and again in the foregoing exposition that only in the first indiscriminating view of things may we regard the events given us in perception as the basis of our concepts of cause and effect. All these events are intricately mixed, those that are given in self perception as well as those given in sense perception. The events of both groups flow along continuously. Consequently, as regards time, they permit a division into parts, which division proceeds, not indeed for our perception, but for our scientific thought, in short, conceptually, into infinity. The events of sense perception permit also conceptually of infinite division in their spatial relations.

It is sufficient for our present purpose, if we turn our attention to the question of divisibility in time. This fact of divisibility shows that the events of our perception, which alone we have until now brought under consideration, must be regarded as systems of events. We are therefore called upon to apportion the causal relations among the members of these systems. Only for the indiscriminating view of our practical _Weltanschauung_ is the perceived event _a_ the cause of the perceived event _b_. The more exact analysis of our theoretical apprehension of the world compels us to dissect the events _a_ and _b_ into the parts _a_alpha , _a_beta, _a_gamma--_b_alpha, _b_beta, _b_gamma, and, where occasion calls for it, to continue the same process in turn for these and further components. We have accordingly to relate those parts to one another as causes and effects which, from the present standpoint of analysis, follow one another uniformly and _immediately_, viz., follow one another so that from this standpoint no other intervening event must be presupposed. In this way we come to have a _well-ordered experience_. The dispositions to such experience which reveal themselves within the field of practical thought taught man long before the beginning of scientific methods not to connect causally day and night with one another, but the rising and setting of the sun with day and night. The theoretical analysis, indeed, goes farther. It teaches that in what is here summed up as rising of the sun and yonder as day, there lie again intricate elements requiring special attention, in our own day extending perhaps to the lines of thought contained in the electro-dynamic theory of light and of electrons. Still the ways of thought remain the same, on all the levels of penetrating analysis. We have throughout to relate to one another as cause and effect those events which, in a well-ordered experience, must be regarded as following one another immediately. The cause is then the _immediate_ uniform _antecedens_, the effect the _immediate_ uniform _consequens_. Otherwise stated, the perceived events that we are accustomed, from the standpoint of the practical _Weltanschauung_, to regard as causes and effects, _e. g._, lightning and thunder, from the theoretical apprehension of the world prove to be infinitely involved collections of events, whose elements must be related to one another as causes and effects in as far as they can be regarded as following one another immediately. No exception is formed by expressions of our rough way of viewing and describing which lead us without hesitation to regard as cause one out of the very many causes of an event, and this, too, not necessarily the immediate uniformly preceding event. All this lies rather in the nature of such a hasty view.

The present limitation of uniform sequence to cases of immediate sequence sets aside, then, the objection from which we started, in that it adopts as its own the essential point in question.

Moreover, the way that leads us to this necessary limitation goes farther: it leads to a strengthening of the empiristic position. It brings us to a point where we see that the most advanced analysis of intricate systems of events immediately given to us in perception as real nowhere reveals more than the simple fact of uniform sequence. Again where we come to regard the intervals between the events that follow one another immediately as very short, there the uniformity of the time relation makes, it would seem, the events for us merely causes and effects; and as often as we have occasion to proceed to the smaller time differences of a higher order, the same process repeats itself; for we dissect the events that make up our point of departure into ever more complex systems of component events, and the coarser relations of uniform sequence into ever finer immediate ones. Nowhere, seemingly, do we get beyond the field of events in uniform sequence, which finally have their foundation in the facts of perception from which they are drawn. Thus there follows from this conceptual refinement of the point of departure only the truth that nothing connects the events as causes and effects except the immediate uniformity of sequence.

None the less, we have to think the empiristic doctrine to the bottom, if we desire to determine whether or not the hypothesis which it offers is really sufficient to enable us to deduce the causal relation. For this purpose let us remind ourselves that the question at issue is, whether or not this relation is merely a temporal connection of events that are given to us in perception or that can be derived from the data of perception.

Besides, let us grant that this relation is as thoroughly valid for the content of our experience as empiricism has always, and rationalism nearly always, maintained. We presuppose, therefore, as granted, that every event is to be regarded as cause, and hence, in the opposite time relation, as effect, mental events that are given to us in self perception no less than the physical whose source is our sense perception. In other words, we assume that the totality of events in our possible experience presents a closed system of causal series, that is, that every member within each of the contemporary series is connected with the subsequent ones, as well as with the subsequent members of all the other series, backward and forward as cause and effect; and therefore, finally, that every member of every series stands in causal relationship with every member of every other series. We do not then, for the present purpose, burden ourselves with the hypothesis which was touched upon above, that this connection is to be thought of as a continuous one, namely, that other members can be inserted _ad infinitum_ between any two members of the series.

We maintain at the same time that there is no justification for separating from one another the concepts, causality and interaction. This separation is only to be justified through the metaphysical hypothesis that reality consists in a multitude of independently existing substances inherently subject to change, and that their mutual interconnection is conditioned by a common dependence upon a first infinite cause.[13] Every connection between cause and effect is mutual, if we assume with Newton that to every action there is an equal opposing reaction.

[Footnote 13: This doctrine began in the theological
evolution of the Christian concept of God. It was first
fundamentally formulated by Leibnitz. It is retained in
Kant's doctrine of the _harmonia generaliter stabilita_ and
the latter's consequences for the critical doctrine of the
_mundus intelligibilis_. Hence it permeates the metaphysical
doctrines of the systems of the nineteenth century in
various ways.]

In that we bring the totality of knowable reality, as far as it is analyzable into events, under the causal relation, we may regard the statement that every event requires us to seek among uniformly preceding events for the sufficient causes of its own reality, namely, _the general causal law_, as the principle of all material sciences. For all individual instances of conformity to law which we can discover in the course of experience are from this point of view only special cases of the general universal conformity to law which we have just formulated.

For the empiristic interpretation, the (general) causal law is only the highest genus of the individual cases of empirically synthetic relations of uniform sequence. Starting from these presuppositions, it cannot be other than a generalization from experience, that is, a carrying over of observed relations of uniform, or, as we may now also say, constant sequence to those which have not been or cannot be objects of observation, as well as to those which we expect to appear in the future. Psychologically regarded, it is merely the most general expression of an expectation, conditioned through associative reproduction, of uniform sequence. It is, therefore,--to bring Hume's doctrine to a conclusion that the father of modern empiricism himself did not draw,--a species of temporal contiguity.