'* make. It would raise the awkward question why at birth there is not as great a power of thinking, and of thinking correctly, as at any subsequent period. It would imply that men are equally wise concerning things of which they have had no experience, as concerning things of which they have ; had experience. It would altogether negative that advance in enlightenment which characterizes human progression. In short, not only is the hypothesis without foundation THE GftOWTH OF INTELLIGENCE. 421 in our knowledge of mental phenomena; but acceptance of it would necessitate rejection of all such knowledge of mental phenomena as we have acquired.
Contrariwise, for the second hypothesis the evidence is overwhelming. The multitudirious facts commonly cited to illustrate the doctrine of association of ideas, support it.. It is in harmony with the general truth that from the ignorance of the infant the ascent is by slow steps to the knowledge of the adult. All theories and all methods of education take it for granted — are alike based on the belief that the more frequently states of consciousness are made to follow one another in a certain order, the stronger" becomes their tendency to suggest one another in that order. The? sayings — cc Practice makes perfect," and " Habit is second nature/* remind us how long-established and universal is; the conviction that such a law exists. Exemplification of it is furnished by the fact that men who, from being differently circumstanced, have had different experiences, reach' different generalizations; and by the fact that a wrong; conception will become as firmly established as a right one, if the external relation to which it answers has been as often repeated. It is in harmony with these among other familiar truths; — that phenomena wholly unrelated in our experience, we have no tendency to think of together; that where a certain phenomenon has occurred in many relations, we usually imagine it as recurring in the relation in which it has most frequently occurred; that when we have | witnessed many recurrences of a certain relation we come / to have a strong belief in that relation; that if a relation I has been daily experienced throughout life with scarcely aiij exception, it becomes difficult for us to conceive it as other-j wise — to break the connexion between the states of con-; sciousness representing it; and that where a relation* has been perpetually repeated in our experience with absolute uniformity, we are entirely disabled from conceiving the negation of it.
SPECIAL STNTHESIS.
The only orders of psychical sequences not obviously inby" this general law, are those classed as r^gjcand Instinctive— those which are apparently established before has been had. B*t it is possible that, rightly Interpreted, the law covers these also. Though reflex and Instinctive sequences are not determined by the experiences of the individual organism manifesting them; yet the experiences of the race of organisms forming its ancestry may have determined them. Hereditary transmission applies to psychical peculiarities ^^^^^phy8^". Eecu^aritie-5-While the modified bodily structure produced by new habits of life is bequeathed to future generations, the modified nervous tendencies produced by such new habits of life are also bequeathed; and if the new habits of life become permanent the tendencies become permanent. Let us glance at the facts.
1 Among the families of a civilized society, the changes of and habit from generation to generation and the intermarriage of families having different occupations and habits, greatly confuse the evidence of psychical heref; dity. Bat It needs only to contrast national characters / to see that i^iital^peculiarities cause<^ / ditary. We know that there are warlike, peaceful, nomadic, i maritime, hunting, commercial, races — races that are independent or slavish, active or slothful; we know that many of these, if not all, have a common origin • and hence it is Inferable that these varieties of disposition, which' have evident relations to modes of life, have been gradually prodaeed In the course of generations. The tendencies to certain combinations of psychical changes have become., organic, In^domesticated anmals^parallel facts . are familiar. Not only*Selbrms and constitutions, but the j dispositions and instincts of horses, oxen, sheep, pigs, fowls, have become different from those of their wild kindred. The various breeds of dogs exhibit numerou^va^eiles of mental character and faculty permanently established THE GROWTH OF INTELLIGENCE. 428 by mode of life; and their several tendencies are spontaneously manifested. A young pointer will point at a covey the first time he is taken afield. A retriever brought up abroad has been remarked to fulfil his duty without instruction. In such cases there is evidently a bequeathed tendency for the psychical changes to take place in a special way.* Even from the conduct of untamed creatures we may gather evidence having like implications. The birds of inhabited countries are far more difficult to approach than those of uninhabited ones. And the manifest inference is, that continued experience of human enmity has wrought organic changes in them— has modified their instincts — has altered the connexions among their psychical states.f Of the two hypotheses, then, the first is supported by no positive evidence whatever, while the second is supported by such positive evidence as we have. That the inner co- •* Had Mr. Darwin's Origin of Species been published before I wrote this paragraph, I should, no doubt, have so qualified my words as to recognize " selection," natural or artificial, as a factor. Being written, however, I prefer to let the passage remain with nothing beyond verbal changes, and to make the needful qualification in a note. I do this partly to avoid an inconvenient complication of the statement. But my chief reason, is that, while holding survival of the fittest to be always a co-operating cause, I believe that in cases like these it is not the chief cause. The reasons for this belief are given in the Principles of Biology, § 166.
t I was somewhat surprised when a very competent critic called in question this modification of instincts in birds; and failing fco remember on what authority I had alleged the fact (which I supposed to be well known) I was unable to justify myself. An American friend, who was present, has since been so good as to forward me a verification, in the form of an incidental remark contained in a letter from Captain William.Reynolds, of the United States Navy. This letter (the original is before me) is written from Brook's Island, described by Captain Eeynolds as a "little midge of sand in the midst of th;e wide Pacific." After giving other particulars of this uninhabited island, he says: — "The biigis won't get out of the way of our people when we land, but show fight and have to be kept off with sticks. During this m$tte, the tropic birds lose their tail feathers, which are plucked from them, as you would pull a blade of grass, while walking over a field." t hesions of psychical states are pre-adjusted to the outer persistences of the relations symbolized, is a supposition which, if taken literally> involves absurdities so great that none now make it in respect of any cohesions save the congenital. That it is the true supposition in so far as this limited range of cases is concerned, no evidence can be given; since only to one present at the creation of an organism is knowledge of pre-adjustment possible. So far. as the facts are accessible, the supposition is wholly at variance with them; and it is entertained only where it cannot be brought face to face with the facts. On the other hand, the supposition that the inner cohesions are adjusted to the outer persistences by accumulated experience of those outer persistences, is in harmony with all our actual knowledge of mental phenomena. Though in so far as reflex actions and instincts are concerned, the experience-hypothesis seems insufficient; yet, its seeming insufficiency occurs only where the evidence is beyond our reach. Nay, even here, such few facts as we can get point to the conclusion that automatic psychical connexions result fronvthe registration- of 'experiences continued for numberless generations.
In brief, the case stands thus: — It is agreed that all psychical relations save the absolutely indissoluble are determined by experiences. Their various strengths are admitted, other things equal, to be proportionate to the multiplication of experiences. It is an unavoidable corollary that an infinity of experiences wiU produce ¥"psychical relation that is indissoluble. Though such infinity of experiences cannot be received by a single individual, yet it may be received by the succession of individuals forming a race. And if there is a transmission of induced tendencies in the nervous system, it is inferable that all psychical relations whatever, from the necessary to the fortuitous, result from the experiences of the corresponding external relations; and are so brought into harmony with them.
THE GROWTH OF INTELLIGENCE. 425 Hence the growth of intelligence at large depends on the ' law, that when any two psychical states occur in immediate succession, an effect is produced such that if the first subsequently recurs there is a certain tendency for the second to follow it.
§ 190. By this law, if it is the true one, must be interpretable all the phenomena, from their lowest to their highest grades. Let us first observe how far the leading deductions agree with the leading facts.
A manifest corollary from the law is that the psychical relations in any organism, will correspond besu to those physical relations it comes most in contact with. The environment in general is infinite. The environment of each order of creature is practically more or less limited. And each order of creature has an environment which, besides being limited, is practically more or less special. The law implies, then, that the psychical relations displayed ' by each order of creature, will be those which recur the. oftenest within the range of its experience. And we know^ the fact to be that they are so.
Contemplating the animal kingdom at large, the first psychical relations established ought to be those answering to the most prevalent environing relations of the simplest kind. Such are just what we find. The stationary polype with outstretched tentacles, contracts on being touched. Now a creature that is not itself moving can be touched only by something in motion. Ami, this universal relation between collision and some moving body, is one of the first to be responded to. When a shadow passing across a rudimentary eye is followed by a movement in the creature possessing that eye, the internal relation between the impression and the motion corresponds with the relation between a passing opacity and a passing solidity in the environment; and this is one of the most general relations. Various analogous cases will suggest themselves.
In the progress of life at large, as in the progress of the individual, the adjustment of inner tendencies to outer persistences, must begin with the simple and advance to the complex; seeing that both within and without, complex relations, being made up of simple ones, cannot be established before simple ones have been established. After experience of some persistent relation A to B in the environment, has generated a persistent relation between the answering psychical states a and 5; and after some other persistent outer relation C to D, has similarly generated a persistent inner relation c to d; then, if in the environment there exists any relation between the relations A to B and C to D, it becomes possible for repeated experiences to generate in the organism a relation between a to I and c to d. But it is manifestly impossible for this to be done until the relations a to & and c to d have been themselves generated. This deduction, too, we see to be in complete conformity with the facts, both ol individual evolution and of general evolution.
Further, it must follow that the only thing required for the establishment of a new internal relation answering to a new external one, is, that the organism shall be sufficiently developed to cognize the two terms of the new relation, and that being thus developed, it shall be placed in circumstances which present the new relation. Here also, there is harmony between the a priori inference and the inference from observation. In our domestic animals there are constantly formed new psychical relations answering to such new physical relations as have terms sufficiently simple to be perceived. And in human civilization we see the truth illustrated in the progress to wider and wider generalizations.
But the validity of these several corollaries will become more^apparent as we proceed. Let us now pass on to contie...growth of Inteliience' under its "leading CHAPTER IV.
REFLEX ACTION.
§ 191. Under its simplest form, Eeflex Action is tbe sequence of a single contraction upon a single irritation. A vague manifestation of this seqnence marks the dawn of sensitive life; and, indeed, it is chiefly because they shrink on being touched, that many of the simpler animals are recognized as living.
But though in the movements of Zoophytes it is foreshadowed, Heflex action proper is exhibited only when we ascend to creatures in which there exist nerves and muscles. In such creatures, the response is effected not through the agency of the one uniform tissue constituting the body, which is at once irritable and contractile; but the irritability is confined to one specialized structure, while the contractility is confined to another specialized structure; and the two structures are placed in such relation that irritation of the one is followed by contraction of the other. Some impression is made on the peripheral termination of a nerve; the molecular motion it sets up is propagated along the nerve until it reaches a ganglion; the large quantity of molecular motion there disengaged, discharges itself along another nerve proceeding from the ganglion to a muscle; and thus the stimulus carried through an afferent nerve to some libero-motor centre, is thence reflected in multiplied amount through an efferent nerve to che contractile agent.
In this simplest form of psychical action we see a single internal relation adjusted to a single external relation. Any one of the suckers on the arm of a cuttle-fish that has been separated from the body, will, under the influence of its own independent ganglion,, attach itself to a substance placed in contact with it — the established relation between the tactual and muscular changes in the sucker and its ganglion, is parallel to the uniform relation between resistance and extension in its environment — the inner cohesion of psychical states is as persistent as is the outer relation between attributes. And if we remember that in the actions of the cuttle-fish this inner relation is perpetually being repeated in response to the outer relation, we see how the organization of it in the species answers to the infinitude of experiences received by the species.
§ 192. Reflex action being the lowest form of psychical life, is, by implication., most nearly related to physical life: in it we see the incipient differentiation of the two. This truth may be discerned from several points of view.
It was shown that the contraction which occurs in a polype when touched, or otherwise stimulated, probably results from the increased vital change which the stimulus produces in the disturbed' tissues (§ 140); and though one of these reflex actions, as of a cephalopod's sucker,, is effected in a more definite and more complicated way, yet it does not so far differ as to be removable from the class of physical actions. Mostly, it would be considered as a misuse of words to call it psychical. So that while as belonging to the order of vital changes which, in their higher complications, we dignify as psychical, it may be convenient to classify it as psychical; yet it must be admitted that in position it is transitional. Again, in well-organized creatures, the physical life is itself regulated by reflex actions. Those rhythmical movements of the alimentary canal which follow the introduction of food, are of reflex origin; as are also KEFLEX ACTION. 429 those processes by which, under the same stimulus, the digestive fluids are prepared and poured out. The various viscera, too, performing each its separate function, must have their relative activities adjusted; and the due balancing of them is effected by reflex action. It is held that the changes in the state of each viscus are impressed on the nerves proceeding to ganglia in the sympathetic, whence they are reflected to the other viscera; so that, for instance, when the stomach has been filled, the stimulus it diffuses through this channel to the heart and lungs, causes them to send it an increased quantity of aerated blood. In yet another respect may we see a close alliance between the physical life and this nascent psychical life. As was shown in a foregoing chapter, the psychical life is broadly distinguished from the physical life by the peculiarity that its changes, instead of being simultaneous and successive, are successive only; but, as was also shown, this peculiarity makes its appearance gradually, and becomes marked only when the psychical life becomes high. Now the reflex actions in which the nascent psychical life is seen, are nearly as much characterized by simultaneity as are the purely physical actions. A great number of these simplest nervous changes go on quite independently in the same organism at the same moment. Once more, the proximity of these reflex actions to the physical life is implied by their unconsciousness. Not only in co-ordinating the visceral processes, but also in co-ordinating the processes of perception, there constantly go on reflex actions of which we have no immediate knowledge; as those by which the focus of each eye is adjusted to distances and the closure of the iris adapted to the quantity of light. Other, reflex actions of which we can take direct cognizance — as that of breathing — can go on without our thinking of th$m. And others which are commonly accompanied by local sensation— as when the foot is withdrawn from something which tickles it — are found to be most energetically per- 4-30 SPECIAL SYNTHESIS.
formed when, from some spinal lesion, local sensation has been abolished. Eemembering how nearly unconscious our own locomotive actions become when we are absorbed in thought,, it is inferable that in creatures whose reflex locomotive actions are congenitally perfect, they are quite uni conscious. The rapid alternations of a centipede's leg or a fly's wing, are probably as automatic as are those of a steam-engine piston; and may be co-ordinated after a generally analogous manner. Just as, in a steam-engine, the arrival of the piston at a certain point is necessarily accompanied by the opening of a valve serving to admit the steam which will drive the piston in the reverse direction; so, in one of these rhythmically-moving organs, the performance of each motion ends in bringing the organ to a position in which the stimulus to an opposite motion acts upon it.
But though, from all points of view, Reflex action is seen to be a species of change very little removed from the ,. physicaf changes constituting vegetative life; yet even in it we may 'discern a fulfilment of the primordial conditions to consciousness. In the lowest conceivable type of con- 1 ^sciousness — that produced by the alternation of two states — 'there are involved the relations constituting the forms of all thought. And such an alternation of two states is just that which occurs in the ganglion connected with one of these rhythmically-moving organs.
§ 193. From that lowest kind of Eeflex action in which a single impression produces a single contraction, the ascent is to complications in the stimuli and in the acts resulting > from them. There is no precise distinction between a single i contraction and a combination of contractions. From the •|! excitation of dispersed muscular fibres to the excitation of fibres aggregated into definite bundles, the transition is insensible; and there is similarly a gradual passage from , single contractions to combinations of contractions. Hence, .under the head of Eeflex action there are classed numerous REFLEX ACTION. 431 cases in wHcli a wliole group of muscular motions results from one impression. The decapitated frog which leaps when one of its feet is irritated, supplies an illustration. To examine the varieties and complexities of Reflex action, is ' the task of the physiologist rather than of the psychologist. Here it concerns us merely to note the bearing of the phenomena on the general argument.
We have to observe that these simplest of psychical changes correspond to external relations which are only one degree more specialized than the relations to which physical changes correspond. While the processes of the purely vegetative life are in adjustment with those most general relations between nutriment, oxygen, temperature, 'moisture, light, which pervade the environment at large; these lowest processes of the animal life are in adjustment with the most general relations of the solid bodies contained in the environment: as those between tangibility and solidity, motion and life, Further, it is to be noticed that in conformity with the s general law of intelligence, we have, in one of these reflex actions, an established connexion between two psychical j states answering to an established connexion between two I external phenomena. Not that the inner tendency is exactly proportioned to the outer persistency. In many cases it is absolute in the organism though by no means absolute in the environment. And this is just what is to be looked for among these manifestations of nascent intelligence; since the adjustment of the inner tendencies to the outer persistencies, being the law of intelligence in the abstract, cannot be fulfilled where the intelligence is incipient.
Lastly may be named the fact, that these iiidissolublyconnected psychical states exist where there are perpetftallyrepeated experiences of the external relations to which they answer.
CHAPTER T.
§ 194. Not using the word as the vulgar do, to designate all other kinds of intelligence than the human, but restricting it to its proper signification, ibstmotjaaaj be described as^^componnd reflex action. I say described rather then define37~*^ line of demarkation can be drawn between it and simple reflex action. As remarked in the last section, the dirigo-motor processes which reflex actions show us, pass by degrees from the simple to the complex; and a cursory inspection of the facts shows us that the recipio-motor processes do the like. Nevertheless we may conveniently distinguish, as a higher order of these automatic nervous adjustments, those in which complex stimuli produce complex movements.
That the propriety of thus marking off Instinct from primitive reflex action may be clearly seen, let us take examples. A cl^d^ immediately it comes out of the egg, not only balancesrtself and runs about, but picks up fragments of food; thus showing us that it can adjust its muscular movements in a way appropriate for grasping an object in a position that is accurately perceived. Obvioi^ly this action, which is proved by the circumstances fco be purely automatic, implies the combination of many stimuli. The excitation of certain retinal nerve-fibres must be one — an excitation which is itself a somewhat special combination of excitations. Another component in the general stimulus must be that proceeding from the muscles by which the eyes are directed. And yet another component must be that proceeding from the muscles which alter the focal adjustments of the eyes. Without impressions proceeding from both these sets of muscles, it would be impossible for the head to be guided in the right direction, or for the beak to be closed at the right moment. Thus the action implies impressions on retinal nerves, impressions on nerves proceeding from muscles which move the eyes, and impressions on nerves proceeding from muscles which adjust their lenses — implies that all these nerves are excited simultaneously in special ways and degrees; and that the complex co-ordination of muscular contractions by which the fly is caught, is the result of this complex co-ordination of stimuli. Of such co-ordinated acts automati-" cally resulting from co-ordinated stimuli, we have many illustrations in ourselves. Though originating in volition; our ordinary movements are performed in a mode just like that described. When putting out the hand to grasp an object before us, we are unconscious of the particular muscular adjustments made. We see the object, and in response to the wish for it the arm is moved in a fiu way. But were any of the various nervous stimuli involved in the perception absent, the arm would not be guided aright. That is to say, the special muscular co-ordination is due to the special co-ordination of sensations received from the eye and its adjuncts: volition being concerned merely in setting the process going. One of these actions of our own differs from that of the newly-hatched fly- catcher mainly in this, that whereas, in ourselves, the impressions and motions, being almost infinitely varied and severally repeated with comparative infrequency, are not congenitally co-ordinated but are co-ordinated in the course of our first years; in the fly-catcher, descended from a race in which a special combination is perpetually repeated by every individual throughout life, this combination is readyorganized.
So that while in the primitive forms of reflex action a single impression is followed by a single contraction; while in the more developed forms of reflex action a single impression is followed by a combination of contractions; in this which we distinguish as Instinct, a combination of impressions is followed by a combination of contractions; and the higher the Instinct the more complex are both the directive and executive co-ordinations. Carrying with us this conception, let us now contemplate the facts in connexion with the general laws we are tracing out.
§ 195. Instinct is obviously further removed from purely physical life than is simple reflex action. While simple reflex action is common to the internal visceral processes and to the processes of external adjustment, Instinct is not. I There are no instincts displayed by the kidneys, the lungs, f the liver: they occur only among the actions of that nervo- J muscular apparatus which is the agent of psychical life. ^ Again, the co-ordination of many stimuli into one stimulus is, so far as it goes, a reduction of diffused simultaneous changes into concentrated serial changes. Whether the combined nervous acts which take place when the fly- I catcher seizes an insect, are regarded as a series passing £, through its centre of co-ordination in rapid succession, or as ^ consolidated into two successive states of its centre of co- | ordination, it is equally clear that the changes going on in 1 its centre of co-ordination have a much more decided linear./ arrangement than have the changes going on in the scattered ganglia of a centipede.
In its higher forms, Instinct is probably accompanied by "a rudimentary consciousness. There cannot be co-ordination of many stimuli without some ganglion through which they are all brought into relation. In the process of bringing .them into relation, this ganglion must be subject to the INSTINCT, 435 influence of each — must undergo many changes. And the quick succession of changes in a ganglion, implying as it does perpetual experiences of differences and likenesses, constitutes the raw material of consciousness. The implica^ tion is that as fast as Instinct is developed, some kind of consciousness becomes nascent.
Further, the instinctive actions are more removed from the actions of simple bodily life in this, that they answer to external phenomena which are more complex: and more special. While the purely physical processes going on throughout the organism respond to those most general relations common to the environment as a whole; while tne simple reflex actions respond to some of the general relations common to the individual objects it contains; these compound reflex actions which we class as instincts, respond to those more involved relations which, characterize certain orders of objects and actions as distinguished from others.
Greater differentiation of the psychical life from the physical life is thus shown in several ways — in the growing distinction between the action of the vegetative and animal systems; in the increasing seriality of the changes in the animal system; in the consequent rise of incipient; consciousness; and in the higher speciality of the outer relations to which inner relations are adjusted: which last is indeed the essence of the advance, to which the others are necessary accompaniments.
§ 196. We are now prepared to inquire how, by_ac- I cumulated experiences, compound reflex actions may be \ developed out of simple ones.
Let us begin with some low aguatic creature possessing rudimentary eyes. Sensitive as such eyes are only to marked changes in the quantity of light, they can be affected by opaque bodies moving in the surrounding water, only when such bodies approach close to them. But bodies carried by their motion very near to the organism, will, by 4-36 SPECIAL SYNTHESIS,