Front Page Titles (by Subject) CHAPTER X.: THE CORRESPONDENCE AS INCREASING IN SPECIALITY. - The Principles of Psychology
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CHAPTER X.: THE CORRESPONDENCE AS INCREASING IN SPECIALITY. - Herbert Spencer, The Principles of Psychology 
The Principles of Psychology (London: Longman, Brown, Green and Longmans, 1855).
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THE CORRESPONDENCE AS INCREASING IN SPECIALITY.
§ 145. From another point of view, the evolution of life is an advance in the Speciality of the correspondence between internal and external relations. In part, this is another aspect of the processes delineated in the last two chapters; and in part, it is a further and a higher process. Just as we saw that in so far as mechanical phenomena are concerned, the extension of the correspondence goes on pari passu in Space and in Time, but that the extension of the correspondence in Time, afterwards takes in many other orders of phenomena; so, though at first the increase of the correspondence in Speciality is inseparable from its extension in Space and Time, yet it presently comes to include innumerable correspondences not comprehended under either of these. Objectively, the entire development of the correspondence is essentially one: the limitations of our intellects prevent us from grasping it as one: and it is an inconvenience accompanying the presentation of it in parts, that the divisions more or less overlap each other.
The first step in the specialization of the correspondence is seen on passing from those simplest of all organisms whose environments are homogeneous both in Space and Time, to those whose environments, though homogeneous in Space, are heterogeneous in Time. It is clear that the yeast-cell, touched on all sides by the elements required for its vital actions, and, during its short life, continuously supplied with them under the needful conditions, exhibits a correspondence in the highest degree general. And it is clear that the tree, which, though constantly bathed with nutritive materials, assimilates them only under particular states of the environment, exhibits, in the adjustment of its internal changes to the recurring external changes, an advance towards speciality of correspondence.
The next step of the same nature—the step which distinguishes, so far as it can be distinguished, the animal kingdom from the vegetable one—takes place when, relatively to the needs of the organism, the environment is heterogeneous both in Time and Space. Generally speaking, we may say that while, to the lowest forms of life, the integrable matter is everywhere present under uniformly available conditions; while, to plants, it is everywhere present, but not under uniformly available conditions; to animals, it is neither uniformly present nor present under uniformly available conditions—it exists in particular bodies irregularly dispersed through the environment, which are to be obtained only by particular actions. And thus, change from a general diffusion of nutriment to a specialization of it, involves a further specialization of the correspondences. Unable to grow by mere passive absorption of surrounding elements, the condition under which alone the organism lives, is, that contact with special masses of matter shall be followed by the special acts required to utilize them. Even while yet there are neither prehensile nor digestive organs, we see, in the Amœba, which wraps itself round, and gradually includes, the small bodies it meets with, how necessary is the connection between this new set of external relations and a new set of internal ones. We see how the existence of its food in a solid form, necessarily implies that the organism shall respond differently to the contacts of solid matter and of fluid matter; and how this is a progress towards speciality of correspondence.
And when there arises the primary division of the tissue into stomach and skin—when the established differentiation in the environment, is met by an established differentiation in the organism—when to the ability to distinguish solid from fluid matter, comes to be added the ability to distinguish different orders of solid matter from each other, we see, dimly shadowed forth, those many successive specializations which accompany the development of the senses. These we have now to consider.
§ 146. Out of the primordial irritability, which (excluding the indeterminate types of life that underlie both divisions of the organic world) characterizes animal organisms in general; and in virtue of which arises the response produced by the contact of solid bodies, as distinguished from the fluid medium; are gradually evolved those various modified kinds of irritability, answering to the various attributes of matter. The fundamental attribute of matter is resistance. The fundamental sense shows itself as a faculty of responding to resistance. And while, in the environment, associated with this attribute of resistance, are sundry other attributes severally distinctive of certain classes of bodies; in the organism, there successively arise faculties of responding to these other attributes—faculties, that is, which enable the organism to adjust its internal relations to a greater variety of external relations—faculties, therefore, which increase the speciality of the correspondence.
This is seen not only in the gradual process of differentiation by which the fundamental irritability gives origin to the senses that recognize the sapid, odorous, visible, and sound-producing properties of things; but it is seen in the series of phases through which each sense advances to perfection. For every higher phase shows itself as an ability to recognize smaller and smaller differences, either of kind or degree, in the attributes of surrounding bodies; and so renders it possible still further to specialize the adjustment of inner to outer relations.
In the case of touch, an advance is early shown in the power to distinguish a large moving mass from a small one, by the force of its collision. This is seen even in the zoophytes, which contract bodily if their tentacles are roughly handled, but draw in particular tentacles only if these are touched lightly. When, as in higher grades of creatures, a muscular system and a concomitant muscular sense are developed, there arises an appreciation of relative degrees of hardness in the objects met with; as is proved by the differences between the actions which follow the contact with soft and hard bodies respectively. Afterwards textures become cognizable, and also amounts of tenacity; as illustrated in the act of a spider testing the strength of its web. Finally, when there come to be complicated prehensile organs, the sizes and shapes of the things laid hold of are perceived; and the conduct modified accordingly. And when all these subdivisions of the faculty of touch are fully developed, as in the human being, we find that between the extremes of hardness and softness a great number of gradations can be appreciated; that an immense variety of textures can be known tactually; and that endless objects can be identified by their differences of size and shape, ascertained by the fingers only.
That special kind of touch which we call taste, and which may be generally, though not accurately, described, as a sense serving to distinguish matters that are soluble from those that are insoluble, presents us with a series of gradations of like kind. Regarding only the lower families of creatures, which, if not without exception aquatic, are in all cases surrounded by a fluid of which water is the chief constituent, it is obvious that, to them, the insoluble bodies are one with the inorganic bodies, and that the soluble more or less completely answer to the organic. In the sea, or a river, matter which permanently continues undissolved, is stone or earth; while matter which, though soluble, is found in a solid form, is something alive. Hence, to those lowest creatures, which feed on any organic substance, the soluble and the insoluble,—the things that have taste, and the things that are tasteless,—stand respectively for food and not-food. From this stage upwards, successive specializations, of which we may presume the first to be in an ability to distinguish organic matter into animal and vegetable, display themselves in the narrowing of the classes of things which are eaten. Fish that take particular baits, insects and quadrupeds that feed on particular plants, illustrate this. Obviously, it is neither needful nor practicable to trace out this progress in detail. It suffices to notice that the higher animals exhibit a power of perceiving an increased number of gustable differences; and that when we reach man, we find the faculty so far developed that it enables him not only to identify a great variety of edible substances, but serves the chemist and the mineralogist in classifying those inorganic compounds which are in any degree soluble.
Smell, which, as before suggested (§ 134), has probably a common origin with touch and taste in the fundamental process of assimilation, and is to all appearance gradually differentiated from these, passes through parallel stages of development. At first, merely, as we may presume, a kind of anticipatory taste, and in common with taste employed to distinguish nutritive from innutritive matters, it more or less manifestly progresses in speciality in proportion as the food is specialized; or to put the facts in logical order:—the ability to select special food, is in most cases dependent on the minuteness of the differences which the smelling faculty can appreciate. Not that this is so throughout; for prey is in many cases recognized by other means than scent: but it is so with most insects and plant-eating quadrupeds; and with a considerable proportion of creatures that are carnivorous. These gradations in the olfactory sense, which are most clearly displayed in the mammalia, reach in some of those that hunt by scent, to a high degree of perfection. Not only do we see in such, an ability to identify the species of creature pursued; but the dog, which, with nose to the ground, traces out his master, shows us that he can not only distinguish by scent one class of bodies from all other classes, but can even distinguish a particular individual belonging to that class, from all the other individuals it contains.
The increasing speciality of the correspondences effected by means of vision, in its ascending stages of development, is still more conspicuous. The lowest form of vision appears to be nothing further than a sensitiveness to the proximity of a body which intercepts the light. Marked differences in the quantity of light, and such surrounding changes as cause these differences, are alone responded to. Presently, when less marked differences become appreciable, and when the sensitive tract on which the rays of light are concentrated, is such that a part of it can be stimulated without the stimulation of the whole; there arises an ability to distinguish adjacent objects by their power to reflect light, as well as by their power to intercept it. The differences in light-reflecting power possessed by white and black bodies having become appreciable, we may presume that a further progress of like nature renders perceptible smaller and smaller gradations in the transition from whiteness to blackness; and so adds to the number of things that can be discriminated. Then to increasing ability to recognize differences in the quantity of light, has to be added an ability to recognize differences in its quality; which, in all probability, arises simultaneously. Things that are red, yellow, and blue, come to be differentiated from each other in their effects on the organism; as well as those that are white and black. And familiar facts clearly show, that in the evolution of the visual faculty, the progress is towards a capacity to discriminate a greater variety of intensities of colour, of intermediate tints, and of degrees of light and shade. Gradually too, as there is developed a more expanded retina, and as, consequently, any marked differences in the areas occupied by images cast upon it become appreciable, there arises a possibility of distinguishing differences of bulk in adjacent objects. The approach of a large body changes the state of a greater portion of the retina than the approach of a small one; whence results an appropriate difference of action. And as in the case of amounts of light and qualities of colour, the successive advances result in the perception of smaller and smaller distinctions. Finally, there is reached the ability to recognize not only size but shape. A further specialization of the sensitive tract—a minuter division of it into separate nervous elements, renders it a fit instrument for this. Employed by an organism of proportionate complexity, an eye of advanced structure gives different impressions, not only according to the number of its component nerve fibres that are simultaneously affected, but according to the particular combinations of them that are simultaneously affected: and the particular combinations, varying as they do with the forms of the bodies seen, serve as stimuli to the appropriately varied actions. All which several kinds of visual development displayed throughout the animal kingdom, end in giving to man the power to identify by the eye an infinity of different objects; and so to make an infinity of particular adaptations in his conduct.
Similarly with hearing. In its lowest form, nothing but a sensitiveness to violent concussions affecting the whole environment, this sense, when localized and developed, becomes a means of distinguishing differences in the strengths of the vibrations; that is—the loudness of the sounds. A moderate sound near to the aural organ, produces a different effect on the organism from one causing a distinct tremor of the whole surrounding fluid; and step by step, as the multiplying apparatus of which the ear essentially consists, exhibits a more perfect construction, a greater number of degrees of intensity become perceptible: as is illustrated by animals which listen, or pursue, or seek refuge, according as some neighbouring noise is faint, or moderate, or startling. Higher endowments of the faculty are further accompanied by increasing ability to discriminate qualities as well as quantities of sound. Birds which answer each other in the woods—birds whose songs are made up of intervals more or less truly answering to musical ones, and which may be taught definite melodies, must obviously be able to recognize a great number of differences in pitch. Parrots, whose range of imitations not only exhibits great compass in pitch, but great variety in timbre, show a power to appreciate that secondary order of qualities by which tones of the same pitch are distinguished from each other. By most domestic quadrupeds, and especially such as answer to their names, marked contrasts of pitch or timbre, or of both, are responded to. And among men, or more strictly speaking, among civilized men, the aural faculty reaches a development which, besides enabling them to recognize numerous adjacent creatures, various mechanical operations, countless natural phenomena, by the sounds that accompany them, further enables them to identify unseen persons by the loudness, pitch, and timbre of their voices, and even to perceive the particular states of feeling in which such persons then are.
Thus, throughout the whole animal kingdom, the specialization of the senses is a measure of the specialization of the correspondences between inner and outer relations—is nothing but a means to such specialization. Not only in the differentiation of the senses from each other, but in the differentiation of each sense into those several divisions which eventually constitute it, and in the differentiation of each of these divisions into the minute subdivisions which render possible the appreciation of minute distinctions, we see a series of subjective modifications fitting the organism to respond to a greater and greater number of those objective modifications which characterize the things in its environment.
§ 147. But the increase of the correspondence in speciality, by no means ends with the development of the senses. Nor is it adequately represented, even among the lower animals, by a description of this development. For, during the same time that the advancing faculties of touch, taste, smell, sight, and hearing, have rendered it possible for the organism to respond to smaller differences in the simpler properties of things, there has been growing up a power of responding to those higher properties of things that are not cognizable by direct sensation. This makes its appearance so gradually, and is so intimately associated with the simpler functions of the senses, that it is scarcely possible to treat of the one without in some degree involving the other. Indeed, in the foregoing section, the boundary line has been crossed, alike in speaking of visible and of tangible form, and, to a smaller extent, in other cases.
What is the essential nature of this higher order of specialized correspondences, it will be more convenient to consider hereafter under another head. For the present, it will suffice to say, that they are seen wherever Space or Time, or both Space and Time, are involved. Let us look at the matter in the concrete.
First it is to be observed, that in themselves, the extensions of the correspondence in Space and in Time, both imply increased speciality of correspondence; differing in kind from that above described, though inseparable from it in origin. A higher development of the eye, gives simultaneously a greater ability to identify distant objects, and a greater ability to discriminate between the relative sizes of near objects. And it is manifest that these connate abilities to identify objects at a distance, and to appreciate differences of apparent magnitude, give together a power of estimating distance: whence must arise differences of action, according as the perceived enemies or prey, are dangerously near or hopelessly remote; and these differences of action imply a new series of special correspondences. Manifestly, also, the extension of the correspondence in Time, involves analogous results: seeing that when, instead of responding only to those brief mechanical sequences which occur close to it, the organism possesses an ability to recognize mechanical sequences of longer duration, and afterwards non-mechanical sequences; and when, as a consequence, instead of meeting all these sequences by some one defensive action, as retreat into its shell, it becomes possible for it to meet them by different actions, according to their lengths; the correspondences must become, by implication, more and more special
This being understood, it will at once be seen that when that speciality of correspondence which exhibits itself in the discrimination of objects from each other, is united with that speciality of correspondence which exhibits itself in the discrimination of distances in Space or Time, there arises a new and a higher order of special correspondences; or more correctly—the previously specialized correspondences are still further specialized. And when, as during this same progress, there is developed a power of recognizing direction in space, the speciality is again increased. To another set of distinctions in the environment, there is another set of adjustments in the organism. These general truths will be best elucidated by a few illustrations.
Among the lower aquatic creatures endowed with some degree of activity, and with vision extending to a few feet, may be observed cases in which the approach of any large object, is responded to simply by a series of convulsive movements, which may end in removing the creature to a greater distance from the approaching body, or in bringing it nearer, or in leaving it nearly where it was. The random leaps which a flea makes in its attempts to escape, are of like nature; showing, as they do, no recognition of the whereabouts of the pursuer. On the other hand, the movements of a fish when alarmed, or of a fly when approached by the finger, are, like those of all higher creatures, away from the object to be escaped. The particular direction of something in the environment, is responded to by a particular adjustment in the motions of the organism—the correspondence is comparatively special. When, again, not only the direction but the nature of a neighbouring body can be perceived, by virtue of its colour, or the sound it makes, or both—as exemplified in the deer that gallops away from a creature that barks but not from one that bleats, in the bee that flies towards a flower, in the trout that rises at one object but not at another—there is a yet further specialization. And as not only colours and sounds and directions, but magnitudes and forms and distances come to be appreciated, there result all those more definitely adjusted actions by which the higher animals elude danger and secure prey—actions such as those of the chamois springing from crag to crag; of the hawk pouncing upon its quarry; of the dog catching the morsel of food thrown to it; of the bird building its nest and feeding its young.
In like manner, that increased speciality involved by extension of the correspondence in Time, when joined with that increased speciality resulting from a better discrimination of objects, gives origin to another series of higher specializations. There is a response to the sequences exhibited by particular classes of bodies; not simply to those exhibited by bodies in general. And manifestly, as fast as the number of sequences that can be distinguished from each other in length, accumulates; and as fast as there is a multiplication in the number of things distinguished from each other; so fast can there be an increase in the number of adjustments of the organism to the special actions going on in its environment. Save in respect to rapid mechanical changes, there are no correspondences of this order among the lower classes of creatures; and, lacking as they do the ability to estimate time, even the higher quadrupeds supply but few and imperfect examples of it. The lion that goes to the river side at dusk to lie in wait for the creatures which come to drink; and the house-dog standing outside the door in the expectation that some one will presently open it; may be cited as approximative instances. But only when we come to the human race, are correspondences of this degree of speciality exhibited with distinctness and frequency. In preparing his weapons against the approaching immigration of certain birds; in putting aside to dry, the skins which he preserves for clothing; in making the fire by which to cook his food; in various of his in-door and out-door actions; the savage adapts his conduct to the special changes undergone by special bodies during definite intervals.
Finally, we reach those still higher cases where there is speciality alike in space, time, and object—where the action of the organism is in correspondence with the changes of a particular thing in a particular spot at a particular period. A large proportion of human actions, even among the uncivilized, are of this nature. The going to certain places, at certain seasons, to gather certain natural productions then fit for use; the endeavour to intercept an animal that is making for a retreat, by getting there before it; these, and numerous daily procedures, exemplify this order of correspondences.
§ 148. Under this, as under previous aspects, an advance of the correspondence between the organism and its environment, is markedly displayed in the course of human progress. Not only is it that in the growth of classifications and nomenclatures we see the establishment of a greater number of distinctions among surrounding things, and a conforming of the conduct to their respective properties—not only is it that in the development of agriculture, the serial changes undergone by a variety of plants and animals have become known, and special materials, times, modes, places, adopted for the production of each—not only is it that the growth of the Arts has involved an incalculable multiplication of special processes adapted to produce special changes in special objects—not only is it that our whole social life, alike in the manufactory, in the shop, on the highway, in the kitchen, displays throughout, the performance of particular actions towards particular things in particular places at particular times; but it is that in what is commonly termed exact science, or rather in the actions that are guided by exact science, civilization presents us with a new and vast series of correspondences altogether transcending in speciality those that preceded them. For this that we call exact science, is in reality quantitative prevision; as distinguished from that qualitative prevision exhibited in ordinary knowledge. The progress of intelligence has gradually given the ability to say, not only that such and such things are related in coexistence or sequence; but that the relation between them involves such and such amounts of space, time, force, temperature, &c. &c. It has become possible to predict, not simply that under given conditions two things will always be found together; but to predict how much of the one will be found with so much of the other. It has become possible to predict, not simply that this phenomenon will occur after that; but to predict the exact period of time at the end of which it will occur, or the exact distance in space at which it will occur, or both. And manifestly, this reduction of phenomena to definite measure, gives to those proceedings of the organism that correspond with them, a degree of precision, a special fitness, far exceeding that possessed by ordinary ones. There is an immense contrast in this respect between the act of the astronomer, who, on a certain day, hour, and minute, adjusts his instrument to watch the commencement of an eclipse; and that of the farmer, who so arranges his work that he may have hands enough for reaping some time in August or September. The chemist, who calculates how many pounds and ounces of quick-lime it will require to decompose and precipitate all the bicarbonate of lime which the water in a given reservoir contains in a certain percentage, exhibits an adjustment of inner to outer relations incomparably more specific than does the washerwoman who softens a tub-full of hard water by a handful of soda. In the completeness of their adaptation to external coexistences and sequences, there is a wide difference between the proceedings of ancient besiegers whose battering rams were indeterminate in their action, and those of the scientific artillery-officer of our own day; who, by means of a specific quantity of powder, consisting of specific ingredients, in specific proportions, placed in a tube at a specific inclination, sends a bomb of specific weight, on to a specific object, and causes it to explode at a specific moment. Similarly with all the results of applied science; which not only gives greater speciality to previous correspondences, but renders possible hosts of correspondences before impossible. And when we bear in mind, not only that science, considered as the development of qualitative prevision into quantitative prevision, is thus distinguished by the relatively high speciality of the correspondences it achieves; but that, as contemplated in its own progress, it has been continually advancing in the precision of its results, alike in astronomy, physics, mechanics, chemistry—has been ever becoming more accurately quantitative, more special in its previsions; it becomes obvious, that even the most transcendent achievements of rationality are but the carrying still further that specialization of the correspondences between the organism and its environment, which is displayed in the evolution of Life in general.
§ 149. To follow the practice adopted in previous chapters, it may be as well here to point out, that this increase in the speciality of the correspondence, like its extension in Space and Time, is both in itself a higher life, and contributes to greater length of life. Inability to distinguish between surrounding bodies of different natures, must necessarily be attended by fatal errors in the conduct pursued towards them; while, conversely, the greater the power to recognize the multitudinous distinctions among such bodies, the greater must be the number of special adjustments that can be made to them, and the more complete must be the self-preservation. The proposition is in essence a truism. It is almost a truism, too, to say, that in proportion to the numerousness of the objects or classes of objects that can be separately identified—in proportion, that is, to the number of distinct attributes and combinations of attributes that can be cognized; and in proportion to the number of coexistences and sequences that can be severally responded to; must be the number, and rapidity, and heterogeneity, of the changes going on within the organism—must be the amount of vitality. Indeed, there is apparently no single formula which so well expresses the entire progress of Life, as this increase in the speciality of the correspondences between inner and outer relations. For, taking the extreme case, it is clear that did the actions of an organism accurately respond to all the coexistences and sequences of all things whatever in its environment, its life would be eternal. And it is equally clear that the infinity of internal changes involved in effecting the correspondence with an infinity of external relations, would imply the highest conceivable degree of vital activity.