Essays · Herbert Spencer
TRANSCENDENTAL PHYSIOLOGY.
But our argument does not commit us to any such far-reaching speculation as this; which we introduce simply as suggested by it, not involved. All we are here concerned to show, is, that the deductive method aids us in interpreting some of the more general phenomena of development. That all homogeneous aggregates are in unstable equilibrium is a universal truth, from which is deducible the instability of every organic germ. From the known sensitiveness of organic compounds to chemical, thermal, and other disturbing forces, we further infer the _unusual_ instability of every organic germ--a proneness far beyond that of other homogeneous aggregates to lapse into a heterogeneous state. By the same line of reasoning we are led to the additional inference, that the first divisions into which a germ resolves itself, being severally in a state of unstable equilibrium, are similarly prone to undergo further changes; and so on continuously. Moreover, we have found it to be equally an _a priori_ conclusion, that as, in all other cases, the loss of homogeneity is due to the different degrees and kinds of force brought to bear on the different parts; so, in this case too, difference of circumstances is the primary cause of differentiation. Add to which, that as the several changes undergone by the respective parts thus diversely acted upon, are changes which do not destroy their vital activity, they must be changes which bring that vital activity into subordination to the incident forces--they must be adaptations; and the like must be in some sense true of all the subsequent changes. Thus by deductive reasoning we get some insight into the method of organization. However unable we are, and probably ever shall be, to comprehend the way in which a germ is made to take on the special form of its race, we may yet comprehend the general principles which regulate its first modifications; and, remembering the unity of plan so conspicuous throughout nature, we may _suspect_ that these principles are in some way concerned in succeeding modifications.
It will be seen that the method of restoration here contended for, is based on the alleged physiological necessity of the connexion between these several peculiarities. The argument used is, not that a scapula of a certain shape may be recognized as having belonged to a carnivorous mammal because we always find that carnivorous mammals _do_ possess such scapulas; but the argument is that they _must_ possess them, because carnivorous habits would be impossible without them. And in the above quotation Cuvier asserts that the necessary correlation which he considers so obvious in these cases, exists throughout the system: admitting, however, that in consequence of our limited knowledge of physiology we are unable in many cases to trace this necessary correlation, and are obliged to base our conclusions upon observed coexistences, of which we do not understand the reason, but which we find invariable.
Now Professor Huxley has recently shown that, in the first place, this empirical method, which Cuvier introduces as quite subordinate, and to be used only in aid of the rational method, is really the method which Cuvier habitually employed--the so-called rational method remaining practically a dead letter; and, in the second place, he has shown that Cuvier himself has in several places so far admitted the inapplicability of the rational method, as virtually to surrender it as a method. But more than this, Professor Huxley contends that the alleged necessary correlation is not true. Quite admitting the physiological dependence of parts on each other, he denies that it is a dependence of a kind which could not be otherwise. "Thus the teeth of a lion and the stomach of the animal are in such relation that the one is fitted to digest the food which the other can tear, they are physiologically correlated; but we have no reason for affirming this to be a necessary physiological correlation, in the sense that no other could equally fit its possessor for living on recent flesh. The number and form of the teeth might have been quite different from that which we know them to be, and the construction of the stomach might have been greatly altered; and yet the functions of these organs might have been equally well performed."
Thus much is needful to give an idea of the controversy. It is not here our purpose to go more at length into the evidence cited on either side. We simply wish to show that the question may be settled deductively. Before going on to do this, however, let us briefly notice two collateral points. In his defence of the Cuvierian doctrine, Professor Owen avails himself of the _odium theologicum_. He attributes to his opponents "the insinuation and masked advocacy of the doctrine subversive of a recognition of the Higher Mind." Now, saying nothing about the questionable propriety of thus prejudging an issue in science, we think this is an unfortunate accusation. What is there in the hypothesis of _necessary_, as distinguished from _actual_, correlation of parts, which is particularly in harmony with Theism? Maintenance of the _necessity_, whether of sequences or of coexistences, is commonly thought rather a derogation from divine power than otherwise. Cuvier says--"None of these parts can be changed without affecting the others; and consequently, each taken separately, indicates and gives all the rest." That is to say, in the nature of things the correlation _could not_ have been otherwise. On the other hand, Professor Huxley says we have no warrant for asserting that the correlation _could not_ have been otherwise; but have not a little reason for thinking that the same physiological ends might have been differently achieved. The one doctrine limits the possibilities of creation; the other denies the implied limit. Which, then, is most open to the charge of covert Atheism?
On the other point we lean to the opinion of Professor Owen. We agree with him in thinking that where a rational correlation (in the highest sense of the term) can be made out, it affords a better basis for deduction than an empirical correlation ascertained only by accumulated observations. Premising that by rational correlation is not meant one in which we can trace, or think we can trace, a design, but one of which the negation is inconceivable (and this is the species of correlation which Cuvier's principle implies); then we hold that our knowledge of the correlation is of a more certain kind than where it is simply inductive. We think that Professor Huxley, in his anxiety to avoid the error of making Thought the measure of Things, does not sufficiently bear in mind the fact, that as our notion of necessity is determined by some absolute uniformity pervading all orders of our experiences, it follows that an organic correlation which cannot be conceived otherwise, is guaranteed by a much wider induction than one ascertained only by the observation of organisms. But the truth is, that there are relatively few organic correlations of which the negation is inconceivable.
If we find the skull, vertebræ, ribs, and phalanges of some quadruped as large as an elephant; we may indeed be certain that the legs of this quadruped were of considerable size--much larger than those of a rat; and our reason for conceiving this correlation as necessary, is, that it is based, not only upon our experiences of moving organisms, but upon all our mechanical experiences relative to masses and their supports. But even were there many physiological correlations really of this order, which there are not, there would be danger in pursuing this line of reasoning, in consequence of the liability to include within the class of truly necessary correlations, those which are not such. For instance, there would seem to be a necessary correlation between the eye and the surface of the body: light being needful for vision, it might be supposed that every eye must be external. Nevertheless it is a fact that there are creatures, as the _Cirrhipedia_, having eyes (not very efficient ones, it may be) deeply imbedded within the body. Again, a necessary correlation might be assumed between the dimensions of the mammalian uterus and those of the pelvis.
It would appear impossible that in any species there should exist a well-developed uterus containing a full-sized foetus, and yet that the arch of the pelvis should be too small to allow the foetus to pass. And were the only mammal having a very small pelvic arch, a fossil one, it would have been inferred, on the Cuvierian method, that the foetus must have been born in a rudimentary state; and that the uterus must have been proportionally small. But there happens to be an extant mammal having an undeveloped pelvis--the mole--which presents us with a fact that saves us from this erroneous inference. The young of the mole are not born through the pelvic arch at all; but in front of it! Thus, granting that some quite _direct_ physiological correlations may be necessary, we see that there is great risk of including among them some which are not. With regard to the great mass of the correlations, however, including all the _indirect_ ones, Professor Huxley seems to us warranted in denying that they are necessary; and we now propose to show deductively the truth of his thesis. Let us begin with an analogy.
Whoever has been through an extensive iron-works, has seen a gigantic pair of shears worked by machinery, and used for cutting in two, bars of iron that are from time to time thrust between its blades. Supposing these blades to be the only visible parts of the apparatus, anyone observing their movements (or rather the movement of one, for the other is commonly fixed), will see from the manner in which the angle increases and decreases, and from the curve described by the moving extremity, that there must be some centre of motion--either a pivot or an external box equivalent to it. This may be regarded as a necessary correlation. Moreover, he might infer that beyond the centre of motion the moving blade was produced into a lever, to which the power was applied; but as another arrangement is just possible, this could not be called anything more than a highly probable correlation. If now he went a step further, and asked how the reciprocal movement was given to the lever, he would perhaps conclude that it was given by a crank. But if he knew anything of mechanics, he would know that it might possibly be given by an eccentric. Or again, he would know that the effect could be achieved by a cam. That is to say, he would see that there was no necessary correlation between the shears and the remoter parts of the apparatus. Take another case. The plate of a printing-press is required to move up and down to the extent of an inch or so; and it must exert its greatest pressure when it reaches the extreme of its downward movement. If now anyone will look over the stock of a printing-press maker, he will see half a dozen different mechanical arrangements by which these ends are achieved; and a machinist would tell him that as many more might readily be invented. If, then, there is no necessary correlation between the special parts of a machine, still less is there between those of an organism.
From a converse point of view the same truth is manifest. Bearing in mind the above analogy, it will be foreseen that an alteration in one part of an organism will not necessarily entail _some one specific set of alterations in the other parts_. Cuvier says, "None of these parts can be changed without affecting the others; and consequently, each taken separately, indicates and gives all the rest." The first of these propositions may pass, but the second, which it is alleged follows from it, is not true; for it implies that "all the rest" can be severally affected in only one way and degree, whereas they can be affected in many ways and degrees. To show this, we must again have recourse to a mechanical analogy.
If you set a brick on end and thrust it over, you can predict with certainty in what direction it will fall, and what attitude it will assume. If, again setting it up, you put another on the top of it, you can no longer foresee with accuracy the results of an overthrow; and on repeating the experiment, no matter how much care is taken to place the bricks in the same positions, and to apply the same degree of force in the same direction, the effects will on no two occasions be exactly alike. And in proportion as the aggregation is complicated by the addition of new and unlike parts, will the results of any disturbance become more varied and incalculable. The like truth is curiously illustrated by locomotive engines. It is a fact familiar to mechanical engineers and engine-drivers, that out of a number of engines built as accurately as possible to the same pattern, no two will act in just the same manner. Each will have its peculiarities. The play of actions and reactions will so far differ, that under like conditions each will behave in a somewhat different way; and every driver has to learn the idiosyncrasies of his own engine before he can work it to the greatest advantage. In organisms themselves this indefiniteness of mechanical reaction is clearly traceable. Two boys throwing stones will always differ more or less in their attitudes, as will two billiard-players. The familiar fact that each individual has a characteristic gait, illustrates the point still better. The rhythmical motion of the leg is simple, and on the Cuvierian hypothesis, should react on the body in some uniform way. But in consequence of those slight differences of structure which consist with identity of species, no two individuals make exactly similar movements either of the trunk or the arms. There is always a peculiarity recognizable by their friends.
When we pass to disturbing forces of a non-mechanical kind, the same truth becomes still more conspicuous. Expose several persons to a drenching storm; and while one will subsequently feel no appreciable inconvenience, another will have a cough, another a catarrh, another an attack of diarrhoea, another a fit of rheumatism. Vaccinate several children of the same age with the same quantity of virus, applied to the same part, and the symptoms will not be quite alike in any of them, either in kind or intensity; and in some cases the differences will be extreme. The quantity of alcohol which will send one man to sleep, will render another unusually brilliant--will make this maudlin, and that irritable. Opium will produce either drowsiness or wakefulness: so will tobacco. Now in all these cases--mechanical and other--some force is brought to bear primarily on one part of an organism, and secondarily on the rest; and, according to the doctrine of Cuvier, the rest ought to be affected in a specific way. We find this to be by no means the case. The original change produced in one part does not stand in any necessary correlation with every one of the changes produced in the other parts; nor do these stand in any necessary correlation with one another. The functional alteration which the disturbing force causes in the organ directly acted upon, does not involve some _particular set_ of functional alterations in the other organs; but will be followed by some one out of various sets. And it is a manifest corollary, that any _structural alteration_ which may eventually be produced in the one organ, will not be accompanied by _some particular set of structural alterations_ in the other organs. There will be no necessary correlation of forms.
Thus Paleontology must depend upon the empirical method. A fossil species that was obliged to change its food or habits of life, did not of necessity undergo the particular set of modifications exhibited; but, under some slight change of predisposing causes--as of season or latitude--might have undergone some other set of modifications: the determining circumstance being one which, in the human sense, we call fortuitous. May we not say then, that the deductive method elucidates this vexed question in physiology; while at the same time our argument collaterally exhibits the limits within which the deductive method is applicable. For while we see that this extremely _general_ question may be satisfactorily dealt with deductively; the conclusion arrived at itself implies that the more _special_ phenomena of organization cannot be so dealt with. * * * * * There is yet another method of investigating the general truths of physiology--a method to which physiology already owes one luminous idea, but which is not at present formally recognized as a method. We refer to the comparison of physiological phenomena with social phenomena.
The analogy between individual organisms and the social organism, is one that has from early days occasionally forced itself on the attention of the observant. And though modern science does not countenance those crude ideas of this analogy which have been from time to time expressed since the Greeks flourished; yet it tends to show that there _is_ an analogy, and a remarkable one. While it is becoming clear that there are not those special parallelisms between the constituent parts of a man and those of a nation, which have been thought to exist; it is also becoming clear that the general principles of development and structure displayed in organized bodies are displayed in societies also. The fundamental characteristic both of societies and of living creatures, is, that they consist of mutually-dependent parts; and it would seem that this involves a community of various other characteristics. Those who are acquainted with the broad facts of both physiology and sociology, are beginning to recognize this correspondence not as a plausible fancy, but as a scientific truth. And we are strongly of opinion that it will by and by be seen to hold to an extent which few at present suspect.
Meanwhile, if any such correspondence exists, it is clear that physiology and sociology will more or less interpret each other. Each affords its special facilities for inquiry. Relations of cause and effect clearly traceable in the social organism, may lead to the search for analogous ones in the individual organism; and may so elucidate what might else be inexplicable. Laws of growth and function disclosed by the pure physiologist, may occasionally give us the clue to certain social modifications otherwise difficult to understand. If they can do no more, the two sciences can at least exchange suggestions and confirmations; and this will be no small aid. The conception of "the physiological division of labour," which political economy has already supplied to physiology, is one of no small value. And probably it has others to give. In support of this opinion, we will now cite cases in which such aid is furnished. And in the first place, let us see whether the facts of social organization do not afford additional support to some of the doctrines set forth in the foregoing parts of this article.
One of the propositions supported by evidence was that in animals the process of development is carried on, not by differentiations only, but by subordinate integrations. Now in the social organism we may see the same duality of process; and further, it is to be observed that the integrations are of the same three kinds. Thus we have integrations which arise from the simple growth of adjacent parts that perform like functions: as, for instance, the coalescence of Manchester with its calico-weaving suburbs. We have other integrations which arise when, out of several places producing a particular commodity, one monopolizes more and more of the business, and leaves the rest to dwindle: witness the growth of the Yorkshire cloth-districts at the expense of those in the west of England; or the absorption by Staffordshire of the pottery-manufacture, and the consequent decay of the establishments that once flourished at Worcester, Derby, and elsewhere. And we have those yet other integrations which result from the actual approximation of the similarly-occupied parts: whence result such facts as the concentration of publishers in Paternoster Row, of lawyers in the Temple and neighbourhood, of corn-merchants about Mark Lane, of civil engineers in Great George Street, of bankers in the centre of the city. Finding thus that in the evolution of the social organism, as in the evolution of individual organisms, there are integrations as well as differentiations, and moreover that these integrations are of the same three orders; we have additional reason for considering these integrations as essential parts of the developmental process, needed to be included in its formula. And further, the circumstance that in the social organism these integrations are determined by community of function, confirms the hypothesis that they are thus determined in the individual organism.
Again, we endeavoured to show deductively, that the contrasts of parts first seen in all unfolding embryos, are consequent upon the contrasted circumstances to which such parts are exposed; that thus, adaptation of constitution to conditions is the principle which determines their primary changes; and that, possibly, if we include under the formula hereditarily-transmitted adaptations, all subsequent differentiations may be similarly determined. Well, we need not long contemplate the facts to see that some of the predominant social differentiations are brought about in an analogous way. As the members of an originally-homogeneous community multiply and spread, the gradual separation into sections which simultaneously takes place, manifestly depends on differences of local circumstances. Those who happen to live near some place chosen, perhaps for its centrality, as one of periodical assemblage, become traders, and a town springs up; those who live dispersed, continue to hunt or cultivate the earth; those who spread to the sea-shore fall into maritime occupations. And each of these classes undergoes modifications of character fitting to its function. Later in the process of social evolution these local adaptations are greatly multiplied.
In virtue of differences of soil and climate, the rural inhabitants in different parts of the kingdom, have their occupations partially specialized; and are respectively distinguished as chiefly producing cattle, or sheep, or wheat, or oats, or hops, or cider. People living where coal-fields are discovered become colliers; Cornishmen take to mining because Cornwall is metalliferous; and the iron-manufacture is the dominant industry where ironstone is plentiful. Liverpool has assumed the office of importing cotton, in consequence of its proximity to the district where cotton goods are made; and for analogous reasons Hull has become the chief port at which foreign wools are brought in. Even in the establishment of breweries, of dye-works, of slate-quarries, of brick-yards, we may see the same truth. So that, both in general and in detail, these industrial specializations of the social organism which characterize separate districts, primarily depend on local circumstances. Of the originally-similar units making up the social mass, different groups assume the different functions which their respective positions entail; and become adapted to their conditions. Thus, that which we concluded, _a priori_, to be the leading cause of organic differentiations, we find, _a posteriori_, to be the leading cause of social differentiations.
Nay further, as we inferred that possibly the embryonic changes which are not thus directly caused, are caused by hereditarily-transmitted adaptations; so, we may actually see that in embryonic societies, such changes as are not due to direct adaptations, are in the main traceable to adaptations originally undergone by the parent society. The colonies founded by distinct nations, while they are alike in exhibiting specializations caused in the way above described, grow unlike in so far as they take on, more or less, the organizations of the nations they sprung from. A French settlement does not develop exactly after the same manner as an English one; and both assume forms different from those which Roman settlements assumed. Now the fact that the differentiation of societies is determined partly by the direct adaptation of their units to local conditions, and partly by the transmitted influence of like adaptations undergone by ancestral societies, tends strongly to enforce the conclusion, otherwise reached, that the differentiation of individual organisms, similarly results from immediate adaptations compounded with ancestral adaptations.
Ideas discussed in this chapter
Text from Project Gutenberg, public domain in the United States.