A Review of the Systems of Ethics Founded on the Theory of Evolution Part 21

A REVIEW OF EVOLUTIONAL ETHICS

PART II

INTRODUCTION

Twenty years ago, any one about to deal with moral science from the standpoint of the Theory of Evolution, might have deemed it necessary to preface his work with a statement of cogent reasons for the a.s.sumption of such a standpoint. At a time when Theology saw in Darwinism only a weapon of the anti-theological party, and when even many scientists were not yet decided as to the worth of the new ideas, the right of the student to make use of them in psychological and ethical investigations might have been a subject for dispute. Yet even in the beginning the att.i.tude of apology was a.s.sumed oftener without, than within, English-speaking countries, for the very reason that exactly among the race from which Darwin sprang, the warfare of his conception of animate nature with older systems was fiercest. At the present date, the att.i.tude of opinion is changed in all countries. The Theory of Evolution has few, if it can be said to have any, enemies among the students of science. "With Louis Aga.s.siz died the last opponent of Darwinism deserving scientific notice," says Haeckel.[87] Theology itself has ceased from extreme hostilities, and many theologians have even found in the idea of Evolution an argument with which to defend teleological doctrine. The present opponents of Darwinism as applied to psychology and ethics rather contest its special worth for these provinces than deny its validity in them. Nevertheless, a universal acceptance cannot be claimed for the theory; and since ethics is, above all other sciences, the one that should most desire to persuade rather than to alienate,--and this the more, the stronger its conviction of its own truth,--it may be well to state or restate some of the reasons which justify, from almost all modern standpoints, at least a tentative application of the ideas of Evolution to ethical theory. Such a statement, or restatement, must be an attempt to demonstrate the validity of the theory in this province, and to give some good reasons for supposing, _a priori_, that a survey of ethical questions from the point of view it furnishes may be of ethical utility. The proof of such utility can be found, ultimately, only in the results of the investigation itself.

There is but one phase of the theological doctrine of Creation with which the mere idea of an evolution of life, by itself considered, is directly at variance; this is the doctrine of Creation as taught by the older Theology, which accepted the opening chapters of Genesis as literal history, not as, by any possibility, an oriental allegory.

Between the theory of Evolution and the idea of Creation as a primal formation of matter with force or motion in accordance with fixed laws, between it and the idea of an initial application of force from without,--an impulsion which set the universe in motion,--between it and the conception of a transcendental guidance through natural law or of a pantheistic order of development, there is no such necessary contradiction as could justify the denial of Evolution from the standpoint of any of these theories. It is, therefore, with the defenders of the older theological doctrine of creation only that an _a priori_ defence of Evolution has to deal.

The argument which this doctrine has always regarded as one of its strongest defences is that of the universality of the notion of a Creating Spirit. But this defence is no longer available; modern research has proved the idea to be by no means universal. Sir John Lubbock says, "The lower races have no idea of a Creation; and among those somewhat more advanced it is, at first, very incomplete." "The lower savages regard their G.o.ds as scarcely more powerful than themselves;... they are not creators; they are neither omniscient nor all-powerful; far from conferring immortality on man, they are not even in all cases immortal themselves."[88] "Stuhr, who was, as Muller says, a good observer of such matters, reports that the Siberians had no idea of a Creator. When Burchill suggested the idea of creation to the Bachapin Kaffirs, these 'a.s.serted that everything made itself,' and that trees and herbage grew by their own will."[89] "As regards Tahiti, Williams observes that the 'origin of the G.o.ds and their priority of existence in comparison with the formation of the earth, being a matter of uncertainty even among the native priests, involves the whole in the greatest obscurity.'"[90] "When the Capuchin missionary, Merolla, asked the queen of Singa in Western Africa who made the world, she, 'without the least hesitation, readily answered, "My ancestors."'"[91] "The Bongos of Sudan had no conception of there being a Creator,"[92] the Adipones, the Californian Indians, before they came in contact with white men, the Crees, the Zulu Kaffirs, the Hottentots, had no idea of a creation. "Even in Sanscrit, there is no word for creation, nor does any such appear in the Rigveda, the Zendavesta, or in Homer."[93] The idea of a creation in any sense is not, then, universal, and cannot be a.s.serted to be innate, _a priori_, primordial, or essential to human nature. Nor, a.s.suming the standpoint of belief in a Creator, is there any ground for supposing that he would have chosen the one rather than any other method of creation. The internal as well as the external difficulties in the way of a too literal exegesis of the Old Testament are rapidly causing the abandonment of dogmatism with respect to this point; and any other interpretation than a literal one cannot, as has been said, logically object to a theory of Becoming based on scientific grounds.

It is in the nature of many of our greatest scientific theories that their simplicity and naturalness in the explanation of facts fill us with a sense of wonder that they had not long before suggested themselves to scientists. If, for instance, we were to attempt, in a Cartesian spirit, to free ourselves from all the prejudice of previous dogma and regard only the general course of nature, we could not logically avoid the conclusion, even from a superficial view, that a theory of the gradual development of existing forms has far more probability on its side than that of a creation from without which broke in upon natural process, and placed ready-made suns and planets in the heavens, and finished beasts and men upon the earth. Everywhere in the organic world we behold the process of growth, the development of germs, the pa.s.sage of the inorganic into the organic, and of the organic into the inorganic again,--change and transformation under natural law.

The difficulty which difference of form and function in the various species offers to a theory of Evolution is by no means so large as has often been claimed; as great difference exists between the oak and the acorn, from which we know it, nevertheless, to spring; as much contrast is exhibited between the brown twigs of the trees and shrubs in winter and the brilliant foliage and flowers which they put forth under the warmer sun of spring; quite as great contrasts may be found, in the life of every human being, between the single cell and the individual completeness attained at birth, between infancy and morally characterized manhood and womanhood, between the vigor of full maturity and the deterioration of age. Even the chasm between the organic and the inorganic is not logically impa.s.sable. The necessity of nourishment is the natural bridge between the two, and the equivalence of conditions and result, the indestructibility of matter and motion, establish at once the necessity of the inference that the organic can exist only at the ultimate expense of the inorganic, from which it is continually renewed. Were our senses such that, having before been closed, they were suddenly opened to the perception of the daily observable facts of growth, these would probably appear to us very nearly as strange, anomalous, and impossible as the changes which, according to the Darwinian Theory, have resulted in the existence of different species; and it is obvious that the public mind, becoming gradually accustomed to the conception of the latter changes, does not now regard them as so wonderful and anomalous as they appeared to it in the beginning.

Processes involving complete change of form may be observed, at the present time, everywhere in nature; but they are observable, everywhere in the organic, as growth without breaches; even a primitive science has always recognized the gradual character of motion, the absence of gaps in the causal chain, at least outside of the initiative action of human will. Such a natural hypothesis of creation as we have above supposed, formed upon crude and superficial, but as far as it goes, logical reasoning from facts of observation, could not regard the process as other than a gradual one, in which simpler forms and conditions must be supposed to have preceded more complex ones; in other words, it could not logically conceive the process as other than an evolution.

Traces of an idea of Evolution may be found in various crude forms in nearly all the earlier Greek philosophers, especially in Anaximander, Herac.l.i.tus, Democritus, Empedocles, and later in Aristotle. Such traces may even be found in many heathen mythologies in contradistinction from the Judaic. The progress of investigation, establishing the universality of natural law and, in every province, the gradual character of change was, before Darwin, as it has been since his work, in the direction of such a theory, as was shown by the ready acceptance with which Darwinism met, if not by the world at large, at least by the majority of scientists. In England, France, and Germany, there were others at work under the influence of thoughts similar to if not identical with those that inspired the researches and experiments of Darwin; and the nebular theory of Kant had already claimed in Astronomy what the Darwinian claimed in Biology. "When Kant, in his Natural History of the Heavens, which has become the fundament of modern Astronomy, says, 'Give me matter and I will make you a world,' what he intended to express was that the natural laws of matter are perfectly competent to render comprehensible to us the development of our well-known solar system."[94]

In the very beginning, the theory of Evolution may be said to have had three distinct branches, represented by the Nebular Theory in Astronomy, Haeckel's Ontogeny, and the Biology of Lamarck, Darwin, Wallace, and Huxley; and to these should properly be added the Sociological Ethics of Spencer, which was not, however, worked out to a complete system. But Du Prel says of later research: "In the progress of modern science, no principle has proved so fruitful as that of evolution. All branches compete with one another in its use, and have brought about by its aid the most gratifying results. Geology interprets the significance of superimposed, hardened strata of the earth's crust in the sense of a history of the earth's development; Biology, in union with the study of fossils, arranges the living and petrified specimens of plants and animals in their order, and constructs a history of the evolution of organic life; Philology prepares a genealogical tree of languages, and finds in it signs which throw light on prehistoric times, and reveal facts forgotten for thousands of years; Anthropology discovers in the form and expression of human beings rudimentary signs that point to a theory of development from lower forms; and, finally, History reveals the evolution of civilization in far-distant historic times; and in all these branches it becomes apparent that we only then understand phenomena when we have comprehended their Becoming."[95]

It is due to the gradual perception of the fact that some such theory as that of Evolution is implied in the very conception of the constancy of nature that there has been a continual decrease of that negative form of criticism which has made much of the gaps in the direct proof. Modern science has so grown to, and by, the theory of Evolution that the overthrow of the latter means nothing more nor less than the destruction of science itself in its highest results. Even those who reject the conclusions of Evolution are found to make use of its methods, and must do so perforce. As the breadth and depth and height of the theory come to be perceived, it is seen that the demand for complete proof is nothing more nor less than a demand for the perfection of all branches of knowledge, the refusal of credit without such proof a refusal to place any confidence in the first principles of scientific theory until it has fully explored the universe and left nothing further to be discovered. But science would have less ground for complaint, if the opponents of Darwinism consistently refused, on the ground of the incompleteness of our knowledge, to form any theory whatever on the subject of man's nature and development, permitting the worth of the evolutional theory to be determined by its future results in application as hypothesis. But the peculiar spectacle is afforded us of a party rejecting a theory supported by numberless facts in all branches, and whose very breaches the direction of discovery continually tends to bridge, in favor of a dogma which cannot point to one scientific fact in its support,--a party demanding absolute perfection of proof as the condition of its acceptance of one theory, while it at the same time fiercely defends a conception of nature of which it cannot furnish the most imperfect proof. It is true that mankind has not beheld the evolution of the whole vegetable and animal kingdom. But neither had any human eye ever yet beheld the planet Neptune when Le Verrier prophesied its existence and calculated its size and position. The theory of Evolution is a reasoning from the constancy of nature, as was that of Le Verrier, only, in the case of the former, we have the observation and calculations of not one scientist alone, but of thousands, on which to rely. To demand of the scientist that he shall produce the organic from the inorganic, and practically demonstrate the change of form and function, and the process of separation of species, before the possibility of such development is conceded, is on a par with demanding of him an actual reproduction of the Glacial Period before the theory of its previous existence shall be accepted. There is no reason for supposing that, if spontaneous generation once took place, the peculiar complication of conditions which produced it will ever again recur or can be artificially constructed.

But science has no desire to be dogmatic. It readily acknowledges the total absence of direct and established proof at this particular juncture of the beginning of life. It can only point to the indirect testimony of Physiological Chemistry and Crystallogeny, to the simplicity of structure and movement in certain forms of life, and finally to the observed constancy of nature. But an exaggerated significance has been given to this chief flaw in the theory of Evolution, by those who, starting with the intention of defending Theology or the dignity of the Human, have been driven back, step by step, to this point, and fail to perceive that, arrived here, they have already abandoned the ground on which contest was possible. What significance a primal creation merely of lowest organisms can have, for either a defence of human dignity or for Christian Theology, it is difficult to perceive. As a matter of choice, it would seem to be more consistent with the omnipotence and dignity of a Creator to suppose that these very simple organisms arose, like other forms, under the action of natural law than that special interference was necessary in just their case. But, supposing such a special Creation, the following questions immediately present themselves from the theological standpoint: Are these special creations endowed with soul? If so, they must be immortal; if not, then soul arises in the process of evolution; if it arises as do all other things, qualities, functions, by growth,--that is, by the addition of infinitesimal increments (as we must, indeed, suppose it to arise if we regard it as "evolved")--then whence come these increments?

If they come direct from a Creator, then surely no special favor towards man in the bestowment of soul can be alleged; and if they arise by natural causes, out of nature, then why may not their first beginning, their first infinitesimal appearance, also be supposed to be due to such causes?

The proof of an increase, a growth, of what have been called distinctively the mental faculties, throughout the animal kingdom, is every day stronger. No one believes, at the present date, with Descartes, that the animals are automata. Differences of mental power would seem to be but differences of degree; the facts all point to such a theory. The more scientific theologians have, indeed, abandoned this with the other minor points of contest above discussed, and devoted their efforts to argument from the moral nature of man. Philology, Anthropology, and Geology testify to mental progress, even in the human species; and if such a progress is a fact, it cannot have been without influence upon the moral nature of man, even supposing the latter to be G.o.d-given. Indeed, a merely physical progress or change cannot have been without such influence; for the most conservative theologians admit the strong action of the body upon the mind. It would seem, then, for all reasons, that an investigation of the process of mental evolution, or of evolution in general, ought not to be without results significant for any system of morality. If it is true that we learn wisdom and morality from human history, this can be so only because history gives us increased knowledge of the constancy of nature in those of its manifestations which specially concern the human, and thus enables us better to judge the present and predict the future. We should suppose that a still wider knowledge of our mental and physical evolution must be of yet greater worth to us in the same manner,--that the disclosure of more extended fields of nature to our vision must afford us new and valuable lessons with regard to ourselves; just as the telescope makes no discovery in the most distant regions of s.p.a.ce that does not prove to have, in the end, its peculiar significance for our own planet. If our investigations should prove fruitless, as all such investigations have been said by some to be, the fact, established _a posteriori_, could not be disputed. But, considering all the points above noticed, such a result could not but astonish us; and we should even be inclined, after all that has been said, to suspect that the fault lay rather in the particular method than in the direction of our research.

FOOTNOTES:

[87] "Naturliche Schopfungsgeschichte," 8th ed., p. 109.

[88] "Origin of Civilization," p. 391.

[89] "Origin of Civilization."

[90] Ibid.

[91] Ibid.

[92] Ibid.

[93] Ibid.

[94] Du Prel: "Die Entwicklungsgeschichte des Weltalls."

[95] "Die Entwicklungsgeschichte des Weltalls."

CHAPTER I

THE CONCEPTS OF EVOLUTION

The preceding considerations have made it evident that the idea of Evolution has undergone a broadening process since Darwin first brought it before the world. It is necessary to glance briefly at some of the chief phases and the general significance of this process in order to define the extent and intent of the concept as far as science has made such definition possible.

To Darwin himself the struggle for existence was always between the unities represented by complete organisms whether as isolated individuals, or in family, tribal, or national groups. Everywhere in his calculations, appearing unchanged in his results, is found the unknown quant.i.ty of variation from ancestral type, the known factors being heredity, and natural and s.e.xual selection in the struggle for existence. Wallace's ideas as to color in birds deprive the theory of s.e.xual selection of one of its most important points of application in Darwin's work. It is, in fact, easy to see that s.e.xual selection cannot neutralize natural selection, that any particular form of s.e.xual selection can arise and finally survive only by a harmony with the direction of natural selection, and that the two must therefore appear, even from any standpoint of freedom of the will, as continually attaining coincidence. It has been said, above, that the struggle for existence was, for Darwin, between the organisms as unities. This consistent position of the specialist has been criticised, from a more general point of view, by Lewes in his essay on the Nature of Life,[96]

in which he a.s.serts that we must logically "extend our conception of the struggle for existence beyond that of the compet.i.tion and antagonism of organisms--the external struggle; and include under it the compet.i.tion and antagonism of tissues and organs--the internal struggle." "Mr.

Darwin," he says, "has so patiently and profoundly meditated on the whole subject, that we must be very slow in presuming him to have overlooked any important point. I know that he has not altogether overlooked this which we are now considering; but he is so preoccupied with the tracing out of his splendid discovery in all its bearings, that he has thrown the emphasis mainly on the external struggle, neglecting the internal struggle; and has thus, in many pa.s.sages, employed language which implies a radical distinction where--as I conceive--no such distinction can be recognized. 'Natural Selection,' he says, 'depends on the survival, under various and complex circ.u.mstances, of the best-fitted individuals, but has no relation whatever to the primary cause of any modification of structure.'[97] On this we may remark, first, that selection does not _depend_ on the survival, but _is_ that survival; secondly, that the best-fitted individual survives because of that modification of its structure which has given it the superiority; therefore, if the primary cause of this modification is not due to selection, the selection cannot be the cause of species. The facts which are relied on in support of the idea of 'fixity of species' show, at any rate, that a given superiority will remain stationary for thousands of years; and no one supposes that the progeny of an organism will vary unless some external or internal cause of variation accompanies the inheritance. Mr. Darwin agrees with Mr. Spencer in admitting the difficulty of distinguishing between the effects of some definite action of external conditions, and the acc.u.mulation through natural selection of inherited variations serviceable to the organism. But even in cases where the distinction could be clearly established, I think we should only see an _historical_ distinction, that is to say, one between effects produced by particular causes now in operation and effects produced by very complex and obscure causes in operation during ancestral development.... Natural Selection is only the expression of the results of obscure physiological processes."

The last statement is one to which Darwin himself would certainly not have objected. It is an extension of the principle implicitly involved in all his work and explicitly stated in his later work, although the chief emphasis is laid on outer conditions. The extension of the idea of compet.i.tion from the outer condition of organisms to the more ultimate physiological unities of organ and tissue is a philosophic gain. It is evident, however, that that for which Darwin is seeking is not a philosophical generalization which shall include outer and inner change under one highest law, but, first of all, the particular causes of particular variation interesting to the specialist in biology. It is made too clear for mistake in "The Variation of Animals and Plants under Domestication" that the uncertainty with regard to such particular forms of cause is the spring of his declaration of our ignorance as to variation. The possibility of an inclusion of lower in higher generalizations he would not deny; though the special laws first occupy his attention. Doubtless, his work is not, as is no man's, wholly free from inconsistencies and contradictions,--which are due, in part, to the fact that every scientific theory is, even in the thought of the individual, an evolution. But the declaration of mystery in the question of variation is not equivalent to a theory of accident, of transcendental mystery, or of some special organic or vital force, such as Claude Bernard especially opposed; it is merely and simply a statement of the mystery of present ignorance. This fact is expressly stated in Darwin's later work. We find, for instance, in the introduction to a letter to the editor of "Nature," written in 1873, the origin of many instincts referred to "modifications or variations in the brain, which we, in our ignorance, most improperly call spontaneous or accidental;" and we have, in "The Variation of Animals and Plants under Domestication,"[98] such pa.s.sages as the following: "When we reflect on the individual differences between organic beings in a state of nature, as shown by every wild animal knowing its mate; and when we reflect on the infinite diversity of many varieties of our domesticated productions, we may well be inclined to exclaim, though falsely, as I believe, that variability must be looked at as an ultimate fact, necessarily contingent on reproduction. Those authors who adopt this latter view would probably deny that each separate variation has its own proper exciting cause. Although we can seldom trace the precise relation between cause and effect, yet the considerations presently to be given lead to the conclusion that each modification must have its own distinct cause." It is "probable that variability of every kind is directly or indirectly caused by changed conditions of life. Or, to put the case under another point of view, if it were possible to expose all the individuals of a species during many generations to absolutely uniform conditions of life, there would be no variability.... The causes which induce variability act on the mature organism, on the embryo, and, as we have good reason to believe, on both s.e.xual elements before impregnation has been effected." Darwin further considers, in this same book, some of the probable particular causes of variation, as given in climate and food. And it may be remarked, in this connection, that Rolph's criticism of the impossibility of progress under conditions of want is irrelevant as applied to Darwin, since the latter himself says expressly: "Of all causes which induce variability, excess of food, whether or not changed in nature, is probably the most powerful";[99] again: "We have reason to suspect that an habitual excess of highly nutritive food, or an excess relatively to the wear and tear of the organization from exercise, is a powerful exciting cause of variability."[100] Rolph's criticism is probably due to forgetfulness of the fact that Darwin limited the struggle for existence to that of complete organisms with one another, and that, under such a limitation of the conception to external struggle, a condition of want cannot be conceived as necessarily precluding a monopoly of abundance by best-fitted individuals.

Theories with regard to the special outer causes and resulting physiological conditions of variation have been gradually added to, as facts on this score have acc.u.mulated. But, as investigation advances, the question is seen to involve all the problems of the intricate chemical and mechanical nature of physiological structure in its manifold forms and degrees of organization. The field stretches out in this direction, under our contemplation, to an indefinite distance; and science appears as yet to have pa.s.sed only the outer limits of its territory.

It is certain that the comparatively recent science of Physiological Chemistry will have many of the decisive words to say on this score, in the future. "When we see the symmetrical and complex outgrowths caused by a single atom of the poison of a gall-insect, we may believe that slight changes in the chemical nature of the sap or blood would lead to extraordinary modifications of structure," says the great seer of evolution himself.[101]

Among special theories of Evolution, a distinction may be made between: (1) such special theories as aim at biological simplification by reduction of all organic variation to one primary form of cellular process; (2) such theories as are content with less ultimate laws, by which the various ascertained forms of change are included in one general statement not involving special physiological or physical theory but applicable to all forms of life; (3) such theories as aim to give distinctive philosophic expression to a generalization like the last named, including in this statement both psychical and physiological phenomena; and (4) such theories as aim at an ultimate expression of the direction of evolution that shall include the phenomena of life, both physiological and psychical, under one head with all other natural phenomena. To the first cla.s.s belong only "provisional" hypotheses, among the best known of which are those of Pangenesis, Perigenesis, and the Continuity of the Germ-Plasm. To the second, which are not merely tentative but have a broad foundation in known fact, belongs Haeckel's theory of Inheritance and Adaptation, a theory restated in substance, from independent research, by Eimer, whose ultimate general factors of a.n.a.lysis are the same with Haeckel's, though he deals, beyond these, with special facts and special theories of his own. Phases of the second cla.s.s often ent.i.tle them to inclusion in the third. An example of the third cla.s.s is found in Spencer's definition, "Life is the continual adjustment of inner relations to outer relations." The fourth and last cla.s.s includes Fechner's "Tendency to Stability" and Spencer's theory of the rhythm of motion (see his "First Principles"), similar to which are certain ideas of Zollner, Du Prel, and others; and similar elements to which are to be found in Haeckel's "Plastidule-Theory." In connection with this cla.s.s, reference may be made to an article by Dr. J. Petzoldt in the "Vierteljahrschrift fur wissenschaftliche Philosophie" under the t.i.tle "Maxima, Minima, und Oekonomie," in which, among others, Fechner's views especially are discussed with reference to an ultimate principle of evolution. The first pages on the "Tendency to Stability" in Fechner's "Ideas concerning the Evolution of the Organic" ("Einige Ideen zur Schopfungs- und Entwicklungsgeschichte der Organismen") are as follows:--

"For the sake of brevity I call relations of position and motions recurring at regular periods, that is after like intervals, in the particles forming a material system or in the centres of whole ma.s.ses conceived as forming a larger system, 'stable relations.' Among such relations is to be reckoned the condition of rest of the particles or ma.s.ses in relation to each other, as the extreme case, which we may call the state of 'absolute stability'; while a dissipation of the particles or ma.s.ses, to infinity, in different directions, const.i.tutes the other extreme of absolute instability.

"We do not speak of 'absolute stability,' but of 'full stability,' in cases where motion still takes place, but this brings continually, in exactly the same periods of time, the same relations of particles or ma.s.ses, not only as regards position, but also as regards velocity and direction of the motion and change of velocity and direction....

"To absolute and full stability may be added, as third case, that of greater or less approach to full stability, which we may term briefly 'aproximate stability'... and of which we have an example in the chief bodies of our solar system.

"It may serve as a simplification of the consideration of stable relations of motion to remark... that, in an isolated system or one under constant outer conditions, exactly or very nearly the same relations of velocity and direction recur when exactly or very nearly the same relations in the position of the particles or ma.s.ses return. As regards the velocity, this follows directly from the principle of the conservation of energy; as regards the direction, it is indisputably possible to a.s.sume the connection of its recurrence with that of the other relations, although I cannot remember that a direct general proof of this has been found.

"With these introductory specifications in mind, let us a.s.sume any number of material particles to be restricted, by forces of some sort, to motion within limited s.p.a.ce, and the system either withdrawn from outer influences or under such as are constant; let us, moreover, suppose the system undisturbed by the interference of psychic freedom, or the latter impossible. In such case, certain initial positions, velocities, and directions of the parts of the system being a.s.sumed, all following states will be determined by these. And now, if there are among these conditions, either present at the beginning, or attained in the course of the motion, any such as have for their result a return of the same states after a given time, then the motion, and so also the positions of the parts conceived as at first undergoing alteration in form and velocity, will, unless they contain the immediate condition of periodic recurrence, continue altering until those of all the possible states are reached which contain the condition of recurrence; until this point is attained, the system will, so to speak, know no rest. Has the recurrence once taken place within a given time, then it must always take place anew within the same time, because the same conditions are there to determine it. And since these conditions are determinative of the whole course of motion from one recurrence to the next, the same course must be repeated; that is, in every like phase of the period a like state of motion will exist. But this gives us full stability of the system, a change, a deviation from the attained stability being possible only through changes in outer influences, the a.s.sumed constancy of which rendered the attainment of stability possible.

"This principle appears at first purely _a priori_; but the a.s.sumption should not be overlooked that there are among the conditions determining the motion such as lead to their own recurrence, and this is to be taken for granted, since it is necessary to a.s.sume that a system must continue to change until, but only until, the conditions of full stability are attained, in case it is attainable; and that this full stability, when once reached, cannot be again destroyed by the action of the system itself. The question presents itself as to how far calculation and experience permit us to lay down a more general principle.

"In a system in which only two particles or ma.s.ses, withdrawn from outer influences, are determined to motion by mutual attraction and the influence of a primary impulse in another direction, calculation shows us that, motion to infinity being excluded, the attainment, and indeed the immediate attainment, of full stability is a necessity; and for swinging pendula and vibrating strings it may be calculated, from the nature of the moving forces, that they would remain in a condition of fully stable motion if outer resistance were removed; for, such obstacles present, they pa.s.s through an approximately stable condition to one of absolute stability. The power of purely mathematical calculation does not go beyond such comparatively simple cases....

"But if we call experience to our aid, it may be a.s.serted, in accordance with very general facts, that, in a system left to itself or under constant outer conditions, and starting from any conceivable state, if not full stability at least a greater or less approximation to it is reached as final condition, from which no retrogression takes place through the inner workings of the system itself. The tendency to approximately stable conditions appears, or the actual state is attained, according to the measure in which variable outer influences are withdrawn. So that so little is lacking to our hypothesis, that, although it has at this point to make up for the impossibility of perfect demonstration, we are nevertheless justified in laying down the following law or principle:--

"In every system of material parts left to itself or under constant outer influences, so, then, in the material system of the universe, in so far as we regard it as isolated, there takes place, motion to infinity being excluded, a continuous progress from more unstable to more stable conditions, up to the attainment of a final condition of full or approximate stability."

From the union of the principle thus stated and that of the conservation of energy "it follows that no unlimited progress of the universe to absolute stability, which consists in perfect rest of the parts, can take place.... The energy manifested in the universe cannot be altered, in general, in its amount, but only in the form in which it manifests itself." "It cannot be a.s.serted that the attainment of full stability in the universe would be the attainment of an eternal rest, but only of the most perfectly adjusted motions, and therefore such motions as would give rise to no variations.... But a condition which brings with it eternal repet.i.tion cannot be reached in finite time."

"To elucidation of this principle of the Tendency to Stability," says Dr. Petzoldt a.n.a.lyzing Fechner's work, "we have only to call to remembrance a number of natural phenomena, such as the ebb and flow of the tide, the circulation of moisture, periodic changes of temperature, and so forth, which exhibit great periods of approximate stability and in which we notice in general no retrogression.

"Not less does the const.i.tution of organisms which are, 'so to speak, const.i.tuted dependent upon periodicity of their functions, and so upon stable relations of their life,' serve to confirm the theory. Only the concept of stability must be extended in their case, since not always the same, but only subst.i.tutive parts of the organic systems tend towards stability.