Chapter XI: Part 11

It is not intended here to emphasise the difference between facts verifiable by experiment, and historical facts; yet it is desirable with reference to all kinds of facts stated on authority, to understand the importance of a criterion of truth. We do accept and we have to accept, every one of us, without any exception, the most discriminate scientist even and most of all the philosopher, innumerable statements of facts as they have been observed by others. We all have to rely on the authority of others. The time of the longest human life would be too short to repeat all the experiments made by others, with a view to verifying them in detail. On the other hand, it is obvious that no statement of facts should be accepted on pure authority. We must have a means, a sieve as it were, by which the wheat can easily be winnowed from the chaff; a sieve that will enable us to discard at once those statements that are positively erroneous. In this way our attention can be confined to statements of things that are possible, those that need not, but _may_ be true. "Possible" in German is very appropriately called _möglich_, i. e. _mayable_.

The criterion of that which 'may be' true is the first step towards ascertaining truth; and although it does not exhaust the methods of arriving at truth it is of greatest consequence, for if properly understood and applied, it would save from the start many useless efforts in the investigation of truth.

* * * * *

The question arises then, What is the criterion of the possible? We reject statements, sometimes, as _prima facie_ untrue. Have we a right to do so? And if we have, by what standard do we determine this?

Let us first take into consideration how people really behave when a statement of new facts is made. Take, for instance, the following case. Two strangers meet; A. and B. Mr. A. relates to Mr. B. some incident of his life. He is apparently a very trustworthy person and during the conversation remains perfectly serious. He tells a ghost story in detail, how a departed friend of his appeared to him in distinctly visible form; he says that the spirit spoke to him and told him many strange things, and that he pointed out to him an imminent danger.

We suppose that on the one hand A. makes his statement in good faith and that on the other hand B. is a spiritualist. Will B. consider A.'s story as possible? B., being a spiritualist, most probably will consider A.'s story as possible, and, if he is convinced of A.'s honesty, he will believe the story the same as if he had experienced it himself; no less than a scientist will rely on the statement of an experiment made by one of his colleagues whose scientific veracity he has no reason to doubt.

Suppose A. tells the same story to C. Mr. C. is an infidel and a materialist. As characteristic features of his personality we might mention that he considers religion as pure superstition originated by the fraud of cunning priests. This man will, we may fairly suppose, laugh at A.'s story, because it appears to him an out and out lie. Mr. A. as well as Mr. B., he who tells and he who believes the story, C. will declare, are either insane or they are both impostors.

The difference of opinion in B. and C. indicates that the criterion of truth is different with different persons and that it depends upon their conception of the world. Men who have the same world-conception will also have the same criterion of truth.

The problem consequently is, whether this criterion of truth (i. e. the criterion of what is possible) is necessarily wholly subjective, or whether we can arrive at an objective criterion. It is apparent that this question is intimately connected with another problem, namely, Is every world-conception necessarily subjective, or, Is it possible to arrive at an objective world-conception? It appears to me that we can; and the ideal of philosophy to-day is just such an objective representation of facts.

The difficulty that presents itself lies mainly in the confusion between facts and our interpretation of facts. If A. declares that he saw a ghost, he does not relate a fact, but his interpretation of a fact. Let us suppose that he tells his story again to a third person D., who is a psychologist. D. most likely will not think him a liar. D. will accept the statement _bona fide_ as a mere interpretation of a fact and will inquire after the causes that produced the hallucination. He may be able, possibly, to lay bare the facts disfigured by the wrong interpretation of A. And having clearly stated the objective state of things he may with the assistance of his experience explain the origin of the whole process, partly from the mental condition and the physiological constitution of A., partly from individual circumstances that gave rise to the hallucination. He will not doubt that something extraordinary has happened to Mr. A. The latter's mind has been, and perhaps still is in an abnormal state. And as to B.'s believing the ghost story, Mr. D. will not think that he is insane; though we may presume that he will regard B.'s views of the world as resting upon unfirm grounds; and he will not believe him to be a man of critical ability.

The notion is very common among idealists that we can never go beyond our subjective states of consciousness. This would be tantamount to saying that there is no difference between dreams and real life, except that a dream is cut off by awaking while life lasts comparatively much longer and ceases with death, which may also be an awakening from a dream. In that case hallucinations would be of the same value as sensations. Both would be interpretations of facts for which we do not have an objective criterion of truth. Interpretations of facts would be the sole facts, and it would be quite indifferent whether they were misinterpretations or correct interpretations.

Take a simple instance. We see a tree. The perception of a tree is an interpretation of a set of facts. Interpretations of facts, whether correct or not, are of course also facts. Thus the perception of a tree is a fact which, if all matter were transparent, would, physiologically considered, appear to the eye of an observer as special vibrations in the brain. But the peculiarity of this fact is that it represents other facts. The question is no longer whether there is a perception of a tree taking place in a brain, but whether this perception is true, i. e., whether it agrees with the facts represented. Every perception has a meaning beyond itself; every perception is a fact representing other facts, and the question of truth or untruth has reference to the agreement between representations and facts represented.

Professor Mach says in his essay "The Analysis of Sensations" (_The Monist_, Vol. I. No. I, p. 65):

"Bodies do not produce sensations, but complexes of sensations
(complexes of elements) form bodies."[53]

[53] Professor Mach in thus speaking of bodies uses the
word in the sense of representations and not in the sense
of objects represented. He calls them in the sentence next
following "thought-symbols for complexes of sensations
(complexes of elements)."

And, certainly, we do not deny that upon a closer analysis the perception of a tree appears as a bundle, or a complex of sensations; there is the green of the leaves, the color of the bark, the different shades of the color indicating its bodily form, the shape of the branches, and their slight motions in the breeze that gently shakes the tree. Yet the perception of a tree does not consist of these sensations alone. All these sensations might be so many isolated sensations; and if they remained isolated, they would not produce the percept of a tree. These sensations are interpreted; they have acquired a meaning and are combined into a unity. It is this unity which constitutes the perception of a tree. This unity has grown from sensations; and that process which develops and, as we have learned, naturally must develop sensations from sense-impressions, and from sensations perceptions that are representative of a group of facts outside of the perceptions themselves,—that process we define as mind-activity.

What does the 'perception of a tree' mean? It means that if the person perceiving it moves in a certain direction and over a certain distance, he will have certain sensations which upon the whole can be correctly anticipated. Every perception and also every sensation contains a number of anticipations. The perception of a tree is in so far to be considered correct, as the anticipations which it contains, and of which it actually consists, can be realised. If and in so far as these anticipations when realised tally with the perception, if and in so far as they justify it, or can justify it, if and in so far as they fulfil the expectations produced by the perception, if and in so far as they make no alteration of the perception necessary, but being in agreement with it confirm the representation it conveys: the perception is said to be true. Moreover, we can predict similar results with regard to beings of a similar constitution.

* * * * *

Now let us suppose that an apple falls from a considerable height to the ground. Knowing, from former experiences, the hardness of the soil as well as the density of the apple, we can anticipate the effect of the fall. The soil will not show any considerable impression, yet one side of the apple will be crushed. In predicting this result we anticipate sensations that we shall have under a certain set of circumstances. In so far as we shall necessarily have these sensations we have to deal with facts. Not as if our sensations constitute the entire existence of facts; our sensations, being the effects of so-called objective processes upon our senses, are only one end of a relation, which as a matter of course never exists without the other end. Sensations are the one end; they depend upon and vary with the other end. Showing within certain limits as many varieties here as occur there, they represent the other end.

We can, and for certain purposes we must, entirely eliminate the subjective and sensory part of our sensations, in order to represent in our minds not how two objects affect our senses of sight or touch but how two or more objects affect each other. Thus we arrive at an objective statement of facts, how the falling apple affects the soil, and the soil the apple; while the relation of both to our senses is to be eliminated. This objective statement of facts is the ideal of all natural sciences. The physicist states the interaction between the falling apple and the soil. He does not care how many sentient beings witness the fall; he does not care about the psychological element in their observations. He abstracts from the subjective elements in their observations as well as in his own, and confines his attention to the objective facts represented in their minds.

The objection to this conception of things is made by a consistent idealist, that these observations must always exist in some mind, they do not exist outside of a mind, and mind can as little go beyond itself as a person can walk outside of his skin. Certainly, observations always exist in some mind; they have always a subjective element. But they have also an objective element. No sensation, no perception, no observation is without an objective feature. This objective feature in a sensation or a perception, and also in an abstract idea, is the element that if true has to agree with other facts outside of the sentient being of whose mind the perception is a part. An idealist who is pleased to deny this would either have to identify hallucinations with sensations, or he would be obliged to consider the objective elements of his mind merely and solely as subjective states, having no representative value. In that case he would necessarily be obliged to consider the facts represented, i. e. the things outside the body, as parts of his mind. This being granted, every mind would appear as congruent and coextensive with the universe. We should have as many universes as there are minds, and yet all universes would be only one and the same universe, their sole difference being that of a difference of centres. With the death of every living creature a universe would die; but notwithstanding the chain of consciousness were broken forever in death, the existence of his mind, being that which is commonly considered as the objective universe, would not cease; merely a view-centre would be lost. That which we have characterised as representations in feeling-substance (which according to our terminology constitutes mind) would be a transient and unessential feature of mind only; and if it should cease to be, mind would still exist in what we have defined as the outside facts, the facts represented in mental symbols. In short, mind would be the All, it would be a synonym of God. And not only all mental beings actually existing or having existed would each, one and all, constitute the universe, but also all potential minds, every atom and all possible combinations of atoms that possibly might play a part in the mental activity of a sentient being, would constitute it.

The views of an idealist who accepts these consequences are undeniably correct, although we may quarrel about the propriety of his terminology. Yet an idealist of this type, we may fairly assume, will have little difficulty in adapting himself to our terminology, and in that case we might easily agree about the possibility of arriving at a criterion of truth; for his world-conception (aside from a difference in terms) might, or rather would be practically the same as ours.

If truth is the agreement of certain mental facts with other facts outside of the mind—if it is the agreement of subjective representations with objective things or states of things represented, the problem is whether we have any means of revising or examining this agreement.

* * * * *

If the world were a chaos, i. e. if the facts of nature were not ruled by law; if every fact were not only individually but also generically different from every other fact, so that no single fact had anything in common with other facts; if they thus had no features in common, there would exist no general properties, and we could form no concepts of _genera_; facts would vary radically and totally, without exhibiting regularities or uniformities other than such as might occasionally and without any reason incidentally originate by haphazard,—in short, if our world were a world of chance and not of law, there would be no criterion of truth. Our world, however, is a world of law and not of chance. Thus all facts, although individually different, are found generically to agree among themselves. No two atoms are, with regard to their position, the same at a given moment; all of them are different somehow in their operation and effectiveness. Nevertheless every one of them moves in strict accordance with exactly the same law of causation. There is not the least change taking place in the universe which is not the precise effect of a special cause. There is rigidity in mutability, unity in variety, determinateness in irregularity, law in freedom, order in anarchy. The unity of law, which in its oneness is comprised in the universality of causation, is so perfect that the different facts cannot be thought of as being generically different. However much they differ specifically, they represent the action of the same law, and this same oneness of nature is the basis of all monism.

Monism of this kind, it has been remarked by a critic of ours,[54] is identical with philosophy. Certainly it is. Every philosophy is or at least attempts to be monism, and in so far only as a philosophy recognises monism does it possess a criterion of truth. This monism may be based upon a correct or a mistaken conception of unity. Upon the correctness of this monism will depend the correctness of the criterion of truth. But it must be understood that without a monism there can be no criterion of truth, and philosophy must become either scepticism, mysticism, or agnosticism.

[54] _The Nation_ quotes the following passage from a former
essay of mine: "The philosophy of the future will be a
philosophy of facts, it will be _positivism_; and in so far
as a unitary systematisation of facts is the aim and ideal
of all science, it will be _monism_." _The Nation_ rejects
this definition of monism and adds: "The search for a unitary
conception of the world or for a unitary systematisation of
science would be a good definition of _philosophy_; and with
this good old word at hand we want no other."

Very well. Call that which we call monism or a unitary
systematisation of knowledge, "philosophy"; we will not
quarrel about names—_dummodo conveniamus in re_. We agree
perfectly with our critic; for we also maintain that monism
(at least, what we consider monism) is philosophy; it is _the_
philosophy.

What then is the criterion of truth for a single fact, be it a sensation, a perception, or an observation? It is this, that if the observation be repeated under the same circumstances it will, to the extent that the circumstances are the same, be again the same; the observer will always make the same observation.

This maxim will do for a statement of facts. If according to this maxim we are in the position to ascertain that the same observation can be made again and again under certain conditions, we gain the assurance that we have to deal with a fact of some kind. But how shall we inquire into the correctness of the interpretation of the fact?

* * * * *

Every living creature and furthermore among human beings every individual man has an idiosyncracy of his own. How can we avoid the errors arising therefrom? We substitute other observers so that we can detect to what extent the individual way of observation influences the result of the experiment. Thus we shall find that some persons are color-blind with reference to red or to green, and we can in this way explain certain mistakes caused by such conditions.

Supposing that all human beings were color-blind we should consider this state as normal; and the discovery of science that certain colors which appear alike to us, are after all, considering their wave-lengths and other qualities, more different than certain other tints which are easily discerned by the eye, would be an unexpected surprise. It would to some extent be analogous to the well-known fact that there are rays of light which are not perceptible to the eye, namely, the so-called chemical rays; their existence has been discovered by their chemical effects.

It might be, although it is not probable, that what appears green to me and what I call green, may appear different to other people, perhaps gray, red, or brown, or some other color that I know not of: yet other people will—just as much as I do—call that peculiar sensation green which they experience under the same conditions, for instance, when seeing the fresh leaves of a tree. It is quite indifferent how variegated in single minds the feelings may be that accompany each kind of sensation. So long as they have for every special objective state a special analogue, they can map out in their minds their surroundings, they can have a correct representation of the world, and so long as they employ the same symbols (words or other signs) for indicating the same objective states, it is quite indifferent whether or not the feelings that are produced in the process of observation vary. It would make no more difference for the general purpose of mental operations, than it would if we were to employ Roman letters, or Italics, or Greek or Hebrew characters to designate the lines and points in explaining a mathematical figure. The main thing is that certain points are marked and represented by some sign which stands for this or that point and for that alone.

To cite another example in illustration of the subjective element of feeling in cognition, we may compare our knowledge of the world to the map of a city. The map may be printed in black, green, red, blue, or any other color. The color in which the map is printed represents the subjective element of feeling, while the form of the lines, their geometrical configuration, contains the objective element of the things represented. The map is good, i. e. its representations are true, if the squares and the streets of the city stand in the same relation among each other, as the little blocks and divisions on the map do. Whether the map is printed in green or blue will make no difference so long as we find everything we want to know about the city represented in a way such that we should be able to set ourselves aright and to find our bearings if we went astray.

The subjective element in mind is not of one half the importance generally attributed to it. The objective element, being that which is represented, is paramount, and it is the aspiration of all the sciences to concentrate their entire attention upon the objective features of observation. Objective truth is what we want, and objective truth is identical with a scientific description of facts.

* * * * *

What then is the criterion of objective truth for the interpretation of facts? Is it not wanting? May it not be that a person, Mr. A., will under given circumstances regularly see a ghost. Indeed we do not doubt that he will, and we can even prove it by experiment. This being so, is not the interpretation of facts as to whether the phenomenon is a real ghost or a mere vision, beyond any criterion of truth?

If the methods of science are reliable, (and they have been justified by their brilliant success,) we have indeed a criterion for the interpretation of facts; and this criterion for the interpretation of facts, no less than the criterion of single observations is based upon monism. If the world is really a universe, if there is oneness in the All, if there is a unity of law throughout nature, our interpretations of the different facts must agree among themselves. They cannot and should not contradict one another; and whenever they do, it is a certain sign that somewhere there is something wrong in our interpretation of facts.

Philosophy has ceased to be a metaphysical world-theory. The interpretation of facts no longer means a hypothetical assumption which will square all the irregularities among facts that we are unable to account for, but simply a methodical systematisation of facts, enabling us to recognise the sameness of law in the irregularities apparent in innumerable individual instances. Interpretation in this sense means harmonisation; it means an orderly arrangement; classification with due discrimination. An explanation of natural phenomena is not the carrying of an hypothesis in to facts out of the realms of our imagination, out of depths unknown, by what might be styled revelation or inspiration, but it is a comparison of facts with facts. The hypothesis we apply to facts must come from facts and must cover facts. That element in an hypothesis which does not cover facts is redundant as an explanation; it is useless as such, or even dangerous; and unless it serves as an aid to thought where ignorance of facts requires some assistance, some allegorical symbol, some auxiliary construction,—unless it is to the scientist what crutches are to the lame,—it must be dropped.

Accordingly, the criterion of truth is the perfect agreement of all facts, of all interpretations and explanations of facts among themselves. If two facts (such as we conceive them) do not agree with each other, we must revise them; and it may be stated as a matter of experience, that our mind will find no peace until a monistic conception is reached. A monistic conception is the perfect agreement of all facts in a methodical system, so that the same law is recognised to prevail in all instances, and the most different events are conceived as acting under different conditions yet in accord with the same law.

* * * * *

It does not lie within the scope of this essay to enter upon the practical application of the principle which we have set forth as the criterion of truth. One hint only may be supplied, to point out the most obvious maxim derivable from it—a maxim that is instinctively obeyed by all scientists and has often been popularly expressed in the sentence: An ounce of fact is worth a hundred pounds of hypothesis, or of any interpretation of facts. All the theories in the world, scientific and economical, our dearest ideals not excepted, and all the most ingenious hypotheses have no value unless they have been derived from, and agree with, the laws that live in the facts of our experience.

The trouble of applying this rule lies mainly in the difficulty of distinguishing between facts and our interpretation of facts. Considering that mind is representativeness in feelings we have to analyse the mind in order to come down to objective facts. The percept of a tree is not the tree; it is an interpretation of a group of facts; it is a mental picture produced by a synthesis of sensations, the latter being caused by sense-impressions. Considering that all the images, ideas, abstract concepts, and theories of which our mind consists are not the facts represented by them but their several interpretations, we at once see how careful we have to be for purposes of philosophical and scientific exactness in the statement of facts.

* * * * *

On this occasion, a few critical remarks concerning the leading essay of this number, "The Architecture of Theories," by Mr. Charles S. Peirce, may be added. Mr. Peirce is one of our subtlest thinkers and logicians, and it is incumbent upon one to reflect twice before criticising any sentence of a man who writes upon the most recondite topics,—upon what I should call the higher mathematics, the differential and integral calculus of logic,—with ease and masterly accuracy. Mr. Peirce's essay "The Architecture of Theories,"[55] presented in this number of _The Monist_, is the first publication of his in which he propounds not mere criticism or the discussion of abstruse logical subjects, but his own positive opinion, presenting in great and clear outlines the foundations of his philosophy.

[55] The term "architecture of theories" seems inappropriate
from the standpoint of a positive conception of the world.
Many monisms have been constructed in the way Mr. Peirce
so well describes in his comparison of these philosophical
systems to the building a house of one and the same material,
for instance _papier mâché_, with roof of roofing paper,
foundations of paste-board, windows of paraffined paper, etc.,
etc. Philosophy, however, is not a construction of a theory
comparable to the building of an edifice; it is rather the
mapping out of the house in which we live for the purpose of
orientation.

The world-conception of Mr. Peirce agrees in one fundamental maxim with our own, but it disagrees with the latter in the main and most important application of this maxim. Mr. Peirce says, "Law is _par excellence_ the thing that wants a reason." This maxim was the guiding star of our inquiry into the fundamental problems of philosophy.[56] The world considered as a universe displaying in all its innumerable actions one and the same law is called a cosmos; if considered as a heap of processes with no common law pervading them it is called a chaos. We found in our inquiry into the forms of existence that the laws of form possess intrinsic necessity. The laws of the form of existence are represented in the laws of formal thought (arithmetic, mathematics, logic, mechanics, and pure natural science). So long as the formal laws hold good, (and we have found in the chapter "Form and Formal Thought" that they will hold good under all circumstances,) any kind of world, whatever materially or dynamically it be, must be a cosmos, and cannot be a chaos. We can imagine that we had a world consisting of some other substance and being different either in the amount or in the action of its energy to this world of ours, but we cannot imagine that a world should exist which does not exhibit the harmony of form, and is not regulated as it were by the formal laws of existence. One plus one would be two in any kind of a world, and obviously all the other more complex statements of formal laws would remain true with the same intrinsic necessity. The truth 'one plus one makes two' contains the universal applicability of causation and of the conservation of matter and energy. Taking this ground we arrived at the conclusion that the world is a cosmos: there is no chaos and there never has been a chaos. A chaos, in the sense of an absolute non-existence of law, is an impossibility.

[56] See the author's _Fundamental Problems_.

Accordingly, we cannot agree with Mr. Peirce that the occurrence of chance "calls for no particular explanation." There is no chance, if chance means absence of law. Chance, if the word be admissible, is a mere subjective conception produced by limited knowledge and signifying a state of things not determinable with the means of knowledge at our disposal. Law once recognised is the death of chance (in the objective sense of the word); and chance, or sport, or chaos, or indeterminacy, or whatever one may call the absence or at least the imperfect cogency of law, far from "calling for no particular explanation," must be classed _prima facie_ among those theories that are _per se_ impossible: These conceptions whether applied to the world at large or to special processes of nature are in contradiction to those interpretations and systematised statements of facts which are most fundamental, most reliable, most indispensable and universal. Whatever generalisation the theory of evolution may be capable of, it is certainly not capable of being applied to law. The formal order of Nature and especially the mechanical laws of physics cannot be thought of as having been developed out of a state of sportive chance; they must be considered as having always been the same as they are now: they are eternal.[57]

[57] Mr. Peirce seems to define Mind as sportive chance; for
according to his theory, as soon as sportiveness assumes fixed
habits, it settles into the mechanical motions which physical
science observes in gravitating masses; and matter is thus
defined as "effete mind."

In stating this difference of opinion, I apprehend a possibility that although Mr. Peirce has stated his case with most admirable and I should say unequivocal clearness, I have misunderstood his views. In a former article of his, Mr. Peirce makes a statement concerning Nature considered as a possible chaos, which seems to concur rather with my views on the subject than with his own. Mr. Peirce says in his fourth Paper on the "Illustrations of the Logic of Science":

"If there be any way of enumerating the possibilities of
Nature so as to make them equally probable, it is clearly
one which should make one arrangement or combination of the
elements of Nature as probable as another.... It would be to
assume that Nature is a pure chaos, or chance combination of
independent elements, in which reasoning from one fact to
another would be impossible; and since, as we shall hereafter
see, there is no judgment of pure observation without
reasoning, it would be to suppose all human cognition illusory
and no real knowledge possible. It would be to suppose that
if we have found the order of Nature more or less regular in
the past, this has been by a pure run of luck which we may
expect is now at an end. Now, it may be we have no scintilla
of proof to the contrary, but reason is unnecessary in
reference to that belief which is of all the most settled,
which nobody doubts or can doubt, and which he who should deny
would stultify himself in so doing.

"The relative probability of this or that arrangement of
Nature is something which we should have a right to talk about
if universes were as plenty as blackberries, if we could put
a quantity of them in a bag, shake them well up, draw out a
sample, and examine them to see what proportion of them had
one arrangement and what proportion another. But, even in
that case, a higher universe would contain us, in regard to
whose arrangements the conception of probability could have no
applicability."

I rest the case here in the hope that the statement of both sides of the problem will contribute to elucidate truth.

EDITOR.

FIVE SOULS WITH BUT A SINGLE THOUGHT.

THE PSYCHOLOGICAL LIFE OF THE STAR-FISH.

The investigation of the psychical faculties of animals is comparable to a journey into fairy-land. We do not know, and according to Du Bois-Reymond, we shall never know, how our own mental activity has originated, yet in spite of this we deliberately form theories and opinions concerning the psychical powers and faculties of other beings that in point of nervous organisation are perhaps altogether different from us! The ancients wisely limited themselves to expressing the intelligence of animals in the form of instructive fables, and in the famous park of Versailles the charming idea was actually carried out of representing the fables of Æsop in a so-called labyrinth, every turn of the intricate lanes of which led to a different group of animals whose speech was symbolised by streams of water spouting from their mouths, and the purport of their imagined utterances was to be read in golden letters upon marble tablets placed at the side. How often have I wandered over the scene of those long since ruined mazes and have thought of the deep meaning that frequently lies in childish pastime of this kind.

But labyrinth aside—when we see an animal perform before our eyes purposive acts; and we recognise that our own thought operates in accordance with definite, rigorous laws; we shall still have to say to ourselves that a comparative animal psychology is after all not necessarily so hopeless a thing as one might be led to believe from the bold, and yet faint-hearted, "Ignorabimus" of the distinguished Berlin physiologist. And as a matter of fact the range of insight obtained in very recent times into this very field is highly encouraging. On this occasion I should like to select for discussion one of the most remarkable of questions, that, namely, which concerns the psychical activity of _many-souled_ animals.

Quite a stir was made some years ago in the scientific world when Haeckel began to philosophise about the souls of cells, or so-called plastidule-souls; for it was patent that the course of life in the individual single cell of an animal or vegetable body flowed on in such strict conformity with reason that it was logically necessary to posit the presence of psychical guidance in the instance in question as much as in the case of composite cellular colonies in higher organic beings,—especially since every single one of these composite organisms begins its life as a simple cell, from which the others afterward spring. The wide-spread opposition that Haeckel's view met with, must be regarded as the result of current and common ignorance of the history of philosophy; since otherwise it must have been known that the idea of a cell-soul or a germ-soul which controls the development of the young, has been propounded by innumerable philosophers, and that it was proclaimed by Daniel Sennert, of Wittenberg, who died in 1637, with perfect consistency as the foundation of all psychological knowledge. Many beings, such as Algæ, Fungi, and Infusoria, never in their lives get beyond the state of a single cell, and yet under the microscope we may observe them seeking light, capturing prey, and in the majority of cases founding families. And when the Genevan Trembley discovered, in 1740, the fact of the divisibility of fresh-water Polyps and showed that after cutting them up every piece grew and developed into a new individual endowed with sensation, will, and other psychical capacities, philosophers began to debate whether there were initially present in every divisible polyp a number of souls in the germinal state, or, if such were not the case, whether the simple soul of a polyp possessed the property of divisibility. The Leipsic theologian Crusius, who died in 1775, declared in favor of the presence in every polyp of a plurality of germinal souls; the Dutch insect anatomist, Peter Lyonnet (died 1796) declared in favor of the divisibility of the single polyp soul.

But let us pass by these subtle speculations to turn to a class of animals in the case of which we may speak with more propriety than in the case of polyps and other zoöphytes of a plural soul, since physically and psychically they act in every respect as if they had grown together out of five or more individuals,—I mean the Echinoderms in general and the Star-fish (_Asteroidea_) in particular. In the following paragraphs, for the sake of brevity, I shall speak of only five-rayed star-fishes, because the sacred number five is the one that lies at the basis of the physical structure of the great majority of star-fishes developed from the egg, and of all other echinoderms, although there really do occur star-fishes which are supplied, some with more and some with less than five rays,—single rays often being cast off and a larger number growing out in their places,—and although many species are regularly and normally supplied with more than five rays. From visits to the sea-shore or to aquariums, at any rate from pictures, my readers all know how a star-fish in general looks. In the first cut which accompanies this article a number of echinoderms are presented. The star-fish is in the centre to the left. It resembles the decorative star of an Order, and has short or long, broad or slender rays, as the case may be, and a disc-shaped central body.

The observation which is most important for our present discussion, and which strikes us on first seeing a star-fish, or its relatives the sea-urchin and the sea-anemone, consists of the fact that these animals possess no head, which even the most insignificant worm or insect does not lack, and that consequently its organs are in want of a guiding, regulative member, possessing externally organs of sense and having within a brain with the power to communicate the requisite commands for the movement and the conduct of the same. On the contrary, each single branch or ray possesses its own individual nervous system; and in the case of the voluntary separation of the rays, which frequently occurs, is able to continue life of its own independent accord, developing itself by the growth of new rays into a new and complete star-fish. (See Fig. 2.) But these five or more nervous systems do not radiate from a common central nerve-ganglion which might be termed a central brain, but are merely joined to a nerve-ring which lies in a common central portion, encircling the esophagus; this nerve-ring in the majority of cases forms a regular polygonic figure, and into each angle of the polygon the nerve-cord of a ray enters. It will be seen from this structural arrangement of things, that the psychical and mental guidance of these animals is entrusted to a board of five members who possess, it is true, sentient communication with each other, but act without the intermediation of a presiding officer.

A cast-off arm re-forming by the sprouting of four new rays.]

We may well look forward with intense interest to the outcome of a psychical administration of this kind, and to tell the truth, until recently its importance has been greatly underestimated. Every inference made with respect to the psychical excitability of an animal must be derived from its movements and actions in various natural and artificially produced positions, by observing what its conduct under these conditions is. To start with, star-fishes, like sea-urchins (which psychically are similarly governed), admit with respect to the position of their bodies a distinction of top and bottom; that is to say, the side on which the mouth lies situated in the centre of the five rays belongs properly face downwards, while the opposite surface is to be regarded as the dorsal side. But the conceptions of a forepart and a hindpart, of a right and a left are not applicable. The rays of the star-fish, like the central disc, also plainly exhibit a distinction of lower and upper parts. Among the real star-fishes (_Asteroidea_) the inferior or ventral surface of the arms is supplied either with two or with four rows of sucker-feet or pedicels, consisting of long, extensile, hollow sacs, which when filled and extended by the water let into their widely ramified ambulacral systems, protrude into the grooves of the arm through openings in the hardened calcareous integument. To level surfaces they easily cling fast by simply drawing back the terminal discs of their tubular feet and thus creating a rarefied atmosphere in the space between the object to which they adhere and the puffed out walls of the extremities of the pedicels. Star-fishes may be seen climbing in this way, with their hundreds and hundreds of tube-feet, up slippery cliffs and even the perpendicular glass walls of aquariums, and they are even able to hang suspended from a horizontal glass ceiling for a considerable length of time after they have been taken out of the water. When they wish to change their position they do it by alternately loosening and fastening their extensile feet in such a way that those loosened reach forward in one and the same direction uniform in all the arms, and fasten themselves to the surface anew, whereupon the others also let loose and go through the same movement in the same direction. The sucker-feet also help to convey to the mouth the food seized at the end of the arms.

In the cut to the left _1_ first advances, then (_5_) and (_2_); _3_ and _4_ remaining at rest. Whereupon (_5_) and (_2_) simultaneously come back to the positions _5_ and _2_, _c_ is lifted and pushed forwards with _1_, while the two rays _3_ and _4_ are pulled along behind. In the figure to the right the same animal first shoves forward the pairs (_1_) (_2_) and (_5_) (_3_), _4_ remaining at rest, and then bends both pairs backwards, dragging only _4_ behind; _c_ is lifted and thrown forward in the direction of the arrow.]

While in this instance, accordingly, the arms, although they are not immovable and bend and approach each other, officiate rather as the bearers of organs than as prehensile and locomotory apparatuses themselves,—the sucker-feet performing the principal tasks and requiring for their work a very finely ramified nervous system; in the case of a certain other division of the star-fishes, the so-called sand-stars (_Ophiuridae_), the arms are thinner and more supple, and act as organs of prehension and locomotion, dispensing more or less entirely with their suctorial pedicels. By alternately thrusting three feet forward (Fig. 3) and then drawing back the two side feet of these three, the five-footed sea-stars move more swiftly than the others, sometimes proceeding by jumps even; but they cannot climb up smooth surfaces, or cliffs, unless irregularities are present which may be grasped by their pliant arms, whereas on the other hand the common star-fishes, which are furnished with sucker-feet, climb best of all on smooth and slippery surfaces, each one of their countless pedicels being able to suspend a considerable weight, in some species as much as twenty-five grammes. In other respects, especially with regard to the ring-shaped connection of the five nerve-cords, their organisation is essentially the same; only in the sand-stars the central portion forms a disc more distinctly separate from the arms, in which former the common organs of feeling and digestion have more fully retracted.

Recognising thus, that the star-fishes and all their relatives act physically like a federal animal-union, composed of five independent animal-states, I called attention in the first edition of my work "Werden und Vergehen" (1876) to the psychological enigma that we were here confronted with a five-fold Siamese monster, as it were, in which five separate persons were brought mentally under the same guidance, or where five minds had to pull, simultaneously, one rope. On account of the absence of a head and a brain in these animals, certain well-known modern animal psychologists have taken the position that their powers of psychical performance are very scanty, and that, in a much fuller sense than was predicated of all animals by the Cartesians, these especially were irrational automatons, or, to use a technical expression, were mere "reflex-organisms," animals in which only direct external excitations evoke with unalterable regularity responsive movements, so that, for example, if any unpleasant excitation were brought to bear on them from any direction they would move in the opposite direction, but world approach if anything became perceptible that excited their desire for food. On this ground the distinguished English animal psychologists Romanes and Ewart claim to have established that these animals actually do respond like machines to external excitations; if they were excited at any part of their body by a wound, by the application of acids, an electric current, or any other irritant, they would run without exception in a straight line in the opposite direction, but if the excitation were applied to any two parts of their body at some distance from each other they would move in the line of the diagonal of the two directions, in accordance with the principle of the parallelogram of forces. Similarly their movements after prey and food (the presence of which at a distance was made known by the emission of odors), their movements toward more brightly illuminated parts of the containing vessel, their flight from the air into the water, their recovery of their normal position when placed on their backs, and finally their so-called autotomy or self-amputation, that is the casting off of their members under the irritation of powerful stimuli—were all held to represent mere automatic responses to prearranged conditions without a trace of intelligence being exhibited.

In view of this condition of things it was a very welcome announcement, that one of the most brilliant representatives of modern experimental physiology and psychology, Professor W. Preyer, at present of Berlin, had determined to undertake a comprehensive series of experiments with these very animals, and was able to carry out his intention at the zoölogical station in Naples, so admirably adapted to the purpose. To obtain clear ideas generally with regard to animal reflex-mechanisms, fitter specimens for experiment could scarcely be presented than the star-fishes, which unite a rare degree of decentralisation, power of independent action, and absence of a cerebral centre, with a nervous system of the minutest ramifications. Here, if anywhere, were simple, clear and transparent results to be expected, and finally information relating to the co-operative activity of different nervous systems. Preyer published the results of his observations in the "Mittheilungen der Zoologischen Station in Neapel" for the years 1886 and 1887, and although he does not regard his labors as completed, the scientific reading public may nevertheless take sufficient interest in the present state of his researches to justify a presentment of the principal and most general results obtained.

In confirmation of the view that previously obtained it was found that these animals actually did respond in a rare degree to given stimuli in a manner determined once for all; it could be foretold with a degree of sureness verging on astronomical certainty, how, for example, the sucker-feet of a star-fish would act if the animal in its normal and sound condition was irritated at this or that place, powerfully or weakly, one time or many times successively, by mechanical or chemical applications, by electric currents, or heated instruments. With all the means of irritation employed the result was always identical, and consisted in the fact that the distensible feet were drawn in at the point of application when the irritation did not extend beyond its region, no matter whether it was applied at the inferior or superior surface of the animal, but that protrusion of the feet never resulted from local irritations of this character so long as they did not exceed a certain intensity. A more powerful irritation, on the other hand, radiating over a greater portion, or over the whole animal, produces a general protrusion of the distensible pedicels, so far as the irritation extends, with the single exception of the point of application itself when the same lies on the inferior surface.

Inasmuch as this swarming protrusion of pedicels may spread over the entire inferior surface when only a single arm is irritated in the neighborhood of its extremity, it follows from this that the nervous excitation must first be conveyed to the ring at the centre in order to radiate thence to the pedicels of the other arms; and from the manner in which the irritation is propagated, the course of the radiation can be accurately followed. Thus, if the irritation of an arm proceeded from the dorsal region, the distensible pedicels of this arm were the first to protrude, then those of the two adjacent arms, and finally those of the two remaining arms, but in the latter not quite out to the extremities unless the irritation exceeded a certain intensity. That is to say, the effect of the irritation was propagated through the inner nerve-ring according to the same laws by which a fluid under pressure or an electric current in a similar conductory system would proceed. But if the connection of the ring was severed at both sides of the irritated arm, the effect would remain confined to that arm. If the connection was broken only on one side the irritation advanced round the other side and reached the severed neighbor last. On the other hand, a powerful irritation of the central disc immediately provoked the extension of all the pedicels. The phenomena recorded occurred moreover in accordance with simple mechanical laws as was expected from the outset, and when the irritations were unusually powerful the effect was manifested by a continuous alternate extension and contraction of the pedicels.

Amputated arms of the common sucker-footed star-fish act like arms isolated at both sides by severance of the nerve-ring, as just explained. Upon local irritation they draw in their pedicels, and protrude them upon being powerfully irritated; they creep forward in a definite direction, and when placed upon their backs are able even to turn themselves over like the uninjured animal. The severed arms of sand-stars are less independent. They twist about aimlessly hither and thither, but if any considerable portion of the central disc and nerve-ring adheres to them they are able to perform adaptive movements. Similarly the disc, with one or two arms attached, is not helpless; and is able to get along quite alone without any arms. We could explain all these movements by so-called reflex actions and might grant also that the mechanism that effects these results operates in this case upon a greater scale and with more independence than in other classes of animals, for the reason that here a real guiding organ is not present.

But whatever might be inferred from the experiments just described in favor of a senseless and unintelligent life of star-fishes, Professor Preyer was nevertheless able by extending his experiments to win the conviction that the old conception of star-fishes being real reflex animals was wholly untenable, since a great number of capacities and capabilities could be verified and provoked, which are intelligible only on the basis of adaptive co-operation and mutual concerted action in the five rays. We shall not discuss here whether this is also proved by the wonderful fact that a star-fish, which fastens its arms to everything possible, never seizes its own arm and thus, like Molière's miser, in its visits to its oyster beds never catches itself for a thief. We might say, indeed, that the arm seeking a hold does not seize its companion because it feels it and has learned by experience that it takes a Münchausen to pull one's self out of a swamp by the tops of one's boots. But we find exactly the same phenomenon among creeping plants, which clasp every kind of support in their way, but never, as Darwin observed, take hold of their own stalks; whence we might assume that there probably exists in these beings some sort of power of reflex inhibition dependent upon a property of the body and developed in consequence of the fact that clasping and grasping parts of itself would involve a useless waste of energy. We shall see, however, that under certain circumstances this instinctive "dread" of contact with self is inoperative.