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Part 2. Theory of Evolution

Lecture 10: Biological Evolution

The Lamarckian, Darwinian, and ultra-Darwinian theories generally compared. Natural selection by itself non-teleological. Attempts to assimilate the biological with the physical. Two difficulties in the way. These lead to the question: Is there not a teleological factor operative throughout biological evolution?

Teleological and non-teleological factors distinguished. Darwin recognised both. Only so far as both are present has ‘struggle for existence’ any meaning. The question raised equivalent to inquiring how far mind is concomitant with life. Naturalism confident that life is the wider conception, and appeals to the facts of plant-life. ‘Continuity’ seems to help it, but really works both ways. The case argued. The levelling-up method the simpler. Objections to this considered: (1) Reflexes; (2) The character of plants again. Recent views on this point.

Restatement of the position reached. Antagonism of organism and environment: the latter, then, not the source of life. ‘Vital force’ unworkable. Turning to the facts of mind see have: (1) Self-conservation; (2) Subjective selection. The meaning and significance of these. Their distinctness from, and relation to, natural selection.

IN passing, as we do in this lecture, to the narrower subject of biological evolution, we find no serious attempt made to account for the origin of life or to reduce the facts of life to those of a mechanism. The problem here is merely to explain the diversity of living forms, and that not by the help of mechanical, but of biological, conceptions. The origin of species by descent from some primitive form is assumed as the starting-point. Then we have two widely different, but not incompatible, theories,—that of Lamarck and that of C. Darwin—to shew how, as the latter puts it, “whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.”1 The doctrine of special creation is, by common consent, disallowed as unscientific. This of course leaves the general question of creation untouched. Still, as respects teleological conceptions, the two dominant theories of biological evolution are by no means on the same footing. The extreme Darwinian theory, as held, for example, by Wallace or Weismann, but strongly discountenanced by Darwin himself, seems—if pressed to its logical consequences—to leave but scant space for any notions of purpose or end.2 Natural selection works blindly upon promiscuous variations blindly produced. So mechanical is the whole milieu that repeated attempts have been made to extend the range of natural selection, so understood, to the evolution of stellar systems, chemical elements, and the like. Such an extension would be impossible with the Lamarckian theory, as the mere citation of the second of the four laws given in the Histoire Naturelle will shew: “The production of a new organ in an animal body results from a new want arising and continuing to be felt, and from the new movement which this want initiates and sustains.”3 According to Lamarck, then, variations are due to a psychical factor; but for the theory of natural selection it is immaterial how they are produced. Given the indefinite production of varying individuals, and given also restriction in the number that can simultaneously exist, and it is obvious that some individuals must be excluded and disappear; if for no other reason, at any rate, for want of standing-room. Unless the selection is a pure affair of chance, the variations themselves must determine it: in one case—the question being one of standing-room say—the highest specific gravity, in another the lowest, might constitute the requisite fitness. So in economic exchange, wherever supply exceeds demand, such principles of selection come into play, and with one commodity cheapness is the ground of fitness, with another taste, with another novelty, with another utility in the narrower sense, and so on. Such instances bring out still further the difference between the Lamarckian and the Darwinian, or more correctly the ultra-Darwinian standpoint. For Lamarck, the fitness must relate primarily and essentially to the competing individual; for Wallace or Weismann it might primarily and essentially relate to the selecting agency. Thus in sorting shot those pellets are selected that roll down an incline quickest; in sorting emery powder those particles are selected that take longest to sink in water. In short, for the ultra-Darwinian view, life need imply no more than the indefinite production of varying individuals. Struggle for Existence here becomes simply a figure of speech, not the stern reality first depicted by Malthus, to whom, I believe, the phrase is due. In the Origin of Species Darwin himself calls attention to this: “I should premise,” he says, “that I use this term in a large and metaphorical sense.”

A similar remark applies to the phrase Natural Selection. As to this let me quote from a letter of Wallace to Darwin (Life, ii, p. 46). He writes: “The term ‘survival of the fittest’ is the plain expression of the fact; ‘natural selection’ is a metaphorical expression of it, and to a certain degree indirect and incorrect, since … Nature … does not so much select special varieties as exterminate the most unfavourable ones.” But even ‘survival of the fittest’ is not a plain expression of what logically follows from the ultra-Darwinian premisses. The notion of fitness is used just as metaphorically as that of struggle or selection, for fitness is in strict propriety a teleological conception, and there is nothing teleological in those premisses. There is only what Mr. Spencer would call equilibration: neither struggle for life, nor selection by nature, nor survival of the best, but simply conservation of the stablest; as in a mass of chemical elements capable of combining, compositions, double decompositions, neutralisations, expulsions go on, stronger affinities and avidities overcoming weaker, till the stablest and most permanent combinations are reached.

The mechanical theory of evolution, indeed, is, as we have seen, bent on assimilating the biological to the chemical in some such fashion. But in the way there are two difficulties. In the first place, if we look broadly at the world of living things and compare it with the inanimate world, we are at once confronted by a striking difference. In the latter we note a general downward trend, the resolution of potential energy into kinetic, and then of available forms of this into unavailable; in other words, we find a uniform tendency to pass in the shortest and easiest way to physical quiescence, fixity, and equilibrium. But in the organic world, on the contrary, we find a steadily increasing differentiation of structure and composition, entailing a large storage of potential energy. We see this as we advance from plants to animals, from invertebrate to vertebrate, from cold-blooded vertebrates to warm-blooded, from brutes to man. And if we take into account what may be regarded as the by-products of living things,—their stores of food, the snares they make, the habitations they build,—the same characteristics are still present, notably so, of course, in the products of human skill. The inorganic world has nothing to match dynamite, Liebig's Extract, a steam-engine, or a ship-torpedo. It is impossible in the present state of our knowledge to bring such results under the facilis descensus principle of least resistance, which dispenses with all conception of guidance and direction, and can give no meaning to adaptation, fitness, or worth. And, as has been urged in earlier lectures, it seems absurd to attempt ever to refer those results to such a source, unless they can at the same time be regarded as rare and exceptional manifestations of that principle when working on a very vast scale.

The second of the difficulties mentioned runs parallel to the first; it is, in fact, this advancing complexity regarded psychologically. Here we are only sure of the latest term of the series; how the earliest terms are constituted we can only vaguely guess. In the case of man and the higher animals, there is no doubt that the instinct of self-preservation and the struggle for existence are realities; no doubt, that needs and wants lead to movements; or that improvement comes only by repetition and effort, that practice makes perfect. The only doubt is whether what is thus acquired in one generation becomes in any measure the inborn heritage of the next; but with this burning question we are not for the moment concerned. We have only to demand recognition of the truth that in this advancing psychical complexity, at any rate, the teleological character of the facts is unmistakable; no other conception is adequate. Thus there arises this question which is for us the important one: Is not this teleological factor operative throughout the whole range of biological evolution at least; so far, that is, as we find the downhill trend distinctive of the inanimate world to be counterworked?

As a preliminary to the discussion of this question, it will be well to define a little more exactly what is to be understood by the phrase ‘teleological factor,’ and to distinguish it from the other factors implied. If Lamarck had happened to ask himself: How the leopard came by its spots, as well as how the giraffe acquired its long neck, it is very unlikely that he would have ventured to give the same explanation of both. Continued use in stretching might have enabled the giraffe to add a cubit to his stature, a continued use to which the need of food might lead; but use or need could hardly help the leopard to change its skin, even though the change should facilitate the capture of its prey. A more probable explanation here is the purely Darwinian one, that skin-colouration being specially liable to vary, a variation simulating the play of sunshine through foliage had favoured the ancestors of the leopard when lying in wait to pounce upon their spoil; and that such variation had been perfected by natural selection. At any rate, though not forgetting much striking evidence of a functional and more or less voluntary connexion between an animal's colour and its immediate surroundings, we may fairly take the leopard's spots, the tiger's stripes, or the lion's tawny hue, as instances of fortuitous or non-teleological4 adaptation. Another factor that may be classed as non-teleological, though it is one of minor importance, is that described by Darwin as “the direct action of external conditions,” such as climate and food. This is the factor on which Buffon laid stress, and to which Buckle and the materialists are fond of appealing, an appeal culminating in the mot of Moleschott, Der Mensch ist was er isst. In contrast to these factors of biological evolution, then, the meaning of what I have proposed to call the teleological factors will become clearer. Among these I think we might enumerate three. First, the Lamarckian principle already referred to, secondly, Darwin's Sexual Selection, and lastly, Human Selection, on which Wallace has the merit of laying especial stress.5

The name of Lamarck has been so long in disrepute that it would be rash to cite any theory of his, if there were not at length among biologists a manifest reversion in his favour. Opposed to the neo-Darwinians who profess to see in natural selection far more than ever Darwin publicly6 claimed for it, there is also a numerous neo-Lamarckian school, who replace the fanciful illustrations that served to discredit Lamarck's speculation by an imposing array of facts in its support. Such materials were not in existence in Lamarck's day; and from the free use of what material there was, he seems to have been cut off, partly by blindness and partly by poverty. It was thus easy for Cuvier, that master of details, to turn the laugh against poor Lamarck, and as the favourite of Napoleon, to use his political influence against “the transformists,” as the Lamarckians were called.7 So it came about that when Darwin was working out his Origin of Species, Lamarck's doctrines were in general discredit, and yet had never received an impartial hearing. Darwin's letters shew his anxiety lest these doctrines should be identified with his own. “Heaven forfend me,” he wrote to Hooker in 1844, “from Lamarckian nonsense of a ‘tendency to progression,’8 ‘adaptations from the slow willing of animals, etc.’ But the conclusions I am led to are not widely different from his; though the views of change are wholly so.” Nevertheless, as time went on, Darwin was led by his own further studies and observations to include the Lamarckian factor among his ‘views of change.’ As Romanes says: The longer he (Darwin) lived … the less exclusive was the rôle which he assigned to natural selection, and the more importance did he attribute to the supplementary factors.” Thus, to quote one instance: in the conclusion to his last edition of the Origin, Darwin protests against those who have misrepresented him as attributing the modification of species exclusively to natural selection, and expressly refers to it as “aided in an important manner by the inherited effects of the use and disuse of parts,”9 i.e. by what is commonly called the Lamarckian factor. There is then after all no imprudence in citing this principle.

In calling this factor teleological there is, of course, no intention of connecting it with the old view that each species was immediately designed and directly fashioned to occupy a fixed place in a supposed ‘plan of creation.’ As already said, Lamarck, equally with Darwin, assumed the evolution of all species from a common source. I call this factor teleological, simply, then, on the ground that it presupposes conscious, or at least sentient, activity directed to the satisfaction of needs, appetites, or desires; psychical activity, in a word, as distinct from physical passivity and inertness. It implies an impulse to self-maintenance and betterment, which so far become ends. Only so far as such conceptions are applicable, is there any meaning in talking of struggles to survive, or in saying, as Darwin does, that “Natural selection acts solely by and for the good of each.”10 Sexual selection, and still more obviously human selection, can be brought under the same head, and call here for no further notice.

And now we may take up again the question: Is this same teleological factor operative throughout the whole range of biological evolution, or is it confined to those higher forms of life which have some obvious resemblance to our own? The question is one that seems to have important bearings on our main inquiry, as I shall hope to shew later on. Broadly put, the question is, How far is mind concomitant with life? With this question neither Lamarck nor Darwin has dealt explicitly; in fact biologists as such, for the most part, ignore it. But naturalism, of course, confidently assumes that life is the wider conception, that mind is but an occasional accompaniment of organisation and is certainly never a cause of it; just as it confidently assumes organisation to be but a special arrangement of inert masses and the effect of mechanical forces. Perhaps, however, on closer inspection, life, so regarded, may prove as insoluble a riddle as mind, so regarded, is likely to prove. Comparing the lower forms of life with the higher, it is at once obvious that the non-teleological factors seem more exclusively the efficient ones the lower down the scale we go, while the teleological factors come more clearly into play the higher we ascend. It is true that even plants respire, imbibe, and assimilate; and that among all but the lowest, as among all but the lowest animals, there are differences of sex. “Still,” it will be replied, “only poets talk of ‘the loves of the plants’; science has no ground for ascribing to them activities determined by hunger and thirst, or other organic needs. And yet how impressively diverse and complex are the developments to which, by the operation of the non-teleological factors, the vegetable kingdom has attained. The apparatus by which the bee orchis or the garden sage secures the aid of insects in its fertilisation, or that by which the crane's-bill or the thistle scatters its seed, exceed in ingenuity the snares of the spider or the ant-lion, are comparable indeed even with human devices like the parachute or the sling. Such instances, too, it must be remembered, are not the exception, but the rule, in the economy of plants; whole libraries might be devoted to the description of them. Such marvels of organisation”—it is argued—“has natural selection accomplished by steadily eliminating unpropitious variations, entirely unaided by any sort of spontaneous impulse, sentient preference, or organic memory,—to say nothing of conceptions so mystical as the entelechies11 of Aristotle, the nisus formativus of later writers, and other notions equally transcendental. If, then, nature alone can advance thus far before psychical phenomena appear at all, why suppose, when these are present, that they are more than concomitant, why attribute to them any share in the organising processes? At every step in the genealogical succession both of plant and animal the germ is built anew into the parental form by a like inevitable process: the acorn is here not more passive than the egg; in each alike the embryo recapitulates the stages by which it has been evolved. Why then suppose psychical factors to be necessary to the one result, when they are dispensed with in the other? It is much like saying that though the coiled spring works the meat-jack, we must suppose a musical box to be worked by the tune it plays.”

Such language, I think, fairly represents the levelling-down method to which naturalism is led. For this method it claims the advantages of clearness and simplicity; on the ground, as urged by Huxley, that by thus extending the range of matter and law, it is enabled to substitute the verifiable for the unverifiable, to replace, by a single objective standpoint, subjective standpoints that may be innumerable. To the psychophysical doctrines in which in culminates, I shall hope to invite attention six months hence. In common with other attempts to make lower categories take the place of higher ones—striking instances of which we have discovered in the exposition of Mr. Spencer—this procedure gains greatly in verisimilitude by the use it can make of the principle of continuity, that cardinal principle of all theories of evolution. But it should not be forgotten that on the levelling-up method the principle of continuity is equally available. The scale of life is just as continuous from Man to the Protista as it is from the Protista to Man. To understand human actions we have to take account of mind; on the one method, then, we carry back this conception of mental determination, our teleological factor in other words, as far as we can. In so doing, we may claim to be describing the unknown in terms of the known. Imagination, it is true, will not enable us to depict what Huxley would call the psychoses of creatures so far beneath us. But that alone does not invalidate the conception; if it did, a good many scientific ideas would become illegitimate. On the other hand, the levelling-down method has always more or less definite pictures to offer of the structure and movements, as also of the phylogeny and the ontogeny of each new member in any series of living forms, as it follows forward the continuous interaction of variants and environment. But then comes the difficulty, which led us first of all to inquire whether teleological factors were not throughout indispensable.

Now, even if we were to grant the theory of psychophysical parallelism, this alone would not justify us in saying that life is a wider fact than mind. Simple forms of life might have as concomitants equally simple forms of mind. We have allowed that the psychologist is here at a disadvantage just as the biologist, or rather the physiologist, is correspondingly at a disadvantage, at the opposite extreme. We cannot certainly discern or imagine the mental states of creatures whose entire organism consists of a single cell. But even the biologist in such a case is found to infer much greater complexity of structure than ever the microscope will enable him to see; the psychologist then is equally entitled to infer the presence of appropriate mental concomitants in these unicellular organisms, if the facts of life as a whole are made clearer by so doing. I have only time to deal here with such general considerations, but, in truth, the more the protoplasmic movements, even of the lowest plants, are studied, the more they are found to resemble actions determined by stimuli and to deviate from the mechanical motions of inert masses.12 To such studies we owe in large measure what its opponents regard as a recrudescence of superstition, and its upholders call ‘neo-vitalism.’ However, without discussing detailed observations, the serious difficulty just now mentioned as besetting the levelling-down method is—to say the least—greatly simplified by the opposite method, which assumes that mind is everywhere coincident with life. That tendency to disturb existing equilibria, to reverse the dissipative processes which prevail throughout the inanimate world, to store and build up where they are ever scattering and pulling down; the tendency to conserve individual existence against antagonistic forces, to grow and to progress, not inertly taking the easiest way, but seemingly striving for the best, retaining every vantage secured and working for new ones,—this complex characteristic of all forms of life belongs also to mind. Correlated with mind these characteristics are intelligible; but to interpret them literally in terms of physical interaction, and apart from mind, is surely impossible. However we resolve the problem as to the connexion of mind and matter, it is then, we may conclude, unquestionably a simplification to infer that wherever a material system is organised for self-maintenance, growth, and reproduction, as an individual in touch with an environment, that system has a psychical as well as a material aspect.

There is one very plausible doctrine not uncommon among psychologists and countenanced, as we should expect, by Mr. Herbert Spencer, that stands in the way of this view. Mr. Spencer, as we have seen, imagines consciousness to arise when physiological processes become too complex to work automatically. Up to that point the reactions of the organism are simply reflexes, beyond it they are volitions: and since we are usually unconscious of reflex movements, and since, moreover, they are usually beyond our control, it is concluded that reflexes only indicate life but do not implicate mind. But looked at more closely, this conclusion is at variance with the principle of continuity, that fundamental axiom of evolutional theory; and it is besides, as I have urged at length elsewhere,13 not really borne out by empirical psychology. Reflex movements are called mechanical or automatic, because of the uniformity, promptness, and precision with which they occur. None the less, even the simplest of them depend on the exact adjustment of structures often very complicated. Accordingly the biologist makes large drafts on time and appeals freely to natural selection to account for their ultimate perfection. But during all this time the various more or less abortive attempts thus leading up to an eventual automatic regularity ought, on Mr. Spencer's theory, to be accompanied by consciousness. Moreover, when we turn to our own experience, this is precisely what we find in all those cases where long practice makes perfect, and where feats of dexterity and the like become, as psychologists say, secondarily-automatic.

Another seeming hindrance to the view I am attempting to propound and defend, is the one I was just now referring to, viz. the character of plants. But strangely enough this difficulty has been in the main removed by the biologists themselves. For it would hardly be going too far to say that Aristotle's conception of a plant-soul, though it would be expressed in other language, is tenable even to-day, at least as tenable as any such notion can be at a time when souls are out of fashion. The popular idea of the three natural kingdoms, mineral, vegetable, animal—plants developing from minerals, and animals from plants, as represented by the ingenious device on the covers of Mr. Spencer's volumes—has been long abandoned. If such tripartite division is retained at all, the animal it would seem should rather precede than follow the plant. For the earliest stages of plant development resemble those of animal development, though according to all the rules of evolutional propriety the converse would hold, if plants were first in order. But modern biology, as I understand, assigns the first place in the organic world to a kingdom of Protista, living things, that is, from which individuals with the definite characteristics of plants and animals were afterwards differentiated. The Protista display in a marked degree the motility and sensibility specially associated with animal life. Certain of these freely-moving creatures are supposed to have assumed a sessile position on the earth, and so to have become plants or earth-parasites, as such developing their capacity to build up protoplasm direct from its mineral constituents, but degenerating in respect of their distinctively animal traits, in consequence of their fixity of habitat. The distinctively animal kingdom, on the other hand, it is conjectured, began with the first protist, who anticipated by untold ages the feat of little Jack Horner, and did what animals have been doing ever since—appropriated and devoured the ready-made protoplasm. “The easy nutrition which ensued,” says Professor Cope, “was probably pleasurable, and once enjoyed was repeated and soon became a habit. The excess of energy thus saved from the laborious process of making protoplasm was available as the vehicle of consciousness and motion.”14 But all such conjectures aside—it is at any rate certain that plant protoplasm and animal protoplasm are essentially one and the same; that the animal functions of motility and sensibility pertain to all protoplasm as truly as the vegetable function of assimilation and reproduction; that from unicellular organisms, the Protista, leading the free-swimming life of animalcules and yet endowed with the plant's power of transforming inorganic matter, there arose both unicellular organisms, the Protozoa, retaining and developing the former characteristics; and also unicellular organisms, the Protophyta, with the antithetic traits; and finally that from the Protozoa and Protophyta respectively all the more complex animal and vegetable organisms have been evolved.

Let me now try by way of recapitulation to explain in what sense I understand mind in thus concluding that it is always implicated in life, or that, in other words, a teleological factor, analogous to that of Lamarck, is operative and essential throughout all biological evolution. Let us begin with the opposition of the living individual, or organism, and its environment. These terms are, in biology, strictly correlative, just as in psychology the terms subject and object are. This correlation is one that only appears with life; the physicist never gets beyond the action and reaction of bodies that are not properly individuals. On looking at this relation of organism and environment more closely, we discover that it is essentially an antagonism. Whether living or dead, the organism is equally a material system, and its death makes no change in what we may call the attitude of the environment. What this attitude is, is therefore shewn by the processes that then ensue. These processes, one and all, belong to the downhill trend characteristic of inorganic changes; adopting, but somewhat extending, a convenient physiological term, they are katabolic. Imagine an organism reduced at length by these processes to a formless aggregate of its elemental constituents. Now imagine this formless aggregate of dead material led back step by step till the living organism is set up once more, and you realize the antagonism between organism and environment. For the processes of organisation that preceded death were the precise opposite of all that follow it; they reversed the dissipative tendency of inanimate matter; in a word, they were uphill processes of guidance and direction—were anabolic.

The actual relation of a given organism to its environment is usually very complex, the environment in large measure consisting of other organisms. But we shall not go wrong, if, for simplicity's sake, we consider only the physical environment, which is indeed the sole environment of organic life taken as a whole. So doing we see the hopelessness of regarding this environment—which itself is not alive, which antagonises life—as possibly itself the source of life. Neither can we assume a specific vital energy or force, as the old vitalists did; for life has not—so far as we can see—the properties of a definite form of energy. Thus, when life disappears, there is no equivalent amount of other energy appearing in its place, which we might regard as the result of its transformation. We cannot call death a form of energy. Life, in short, seems to consist in the guidance and control of the known forms of energy, molar and molecular. Quite possibly, beside them, there may be unknown forms of energy, but hardly, as commonly understood, such as would explain life itself. For energy—unless there be what might be vaguely called higher forms of it—is directionless, and all physical forces, so to say, katabolic. The progress of knowledge, in fine, discourages all attempts to treat life as a sort of tertium quid, mediating between matter and mind. Turning then to the facts of mind, a sound method will lead us first to the daylight of our own conscious experience, not to the glimmering twilight of primitive sentience and instinct. Looking broadly at the facts of mind from this standpoint, we come upon two principles that lead us straight to the teleological factors of organic evolution. One of these is the principle of self-conservation—the wide reach and significance of which Spinoza was one of the first to see;15 the other is a principle which I ventured many years ago to call the principle of subjective or hedonic selection.16 These principles furnish natural selection with the που̑ στω̂ it seems to demand. Without these it is difficult to see what purchase it can have, as I will try to shew presently. But first, a word concerning the principles themselves.

I do not need to weary you with any laboured psychological analysis. It is enough to note that both these principles imply feeling and activity; they imply, too, that the activity is prompted by the feeling. Thus, self-conservation, i.e. the conservation of self by self, presupposes the will to live and the pain of dying. It spews itself especially, any unfavourable change in the environment having occurred, in the reactions to this change, which frequently so much exceed the energy of the occasioning stimulus. Apropos of this, organisms are often compared to delicate machinery provided with ‘self-regulating’ valves, with hair-triggers, and with other devices, for nicely controlling large stores of potential energy or setting it free on slight provocation. No doubt there are many points of analogy between organisms and such ingenious contrivances. But it is forgotten that the said contrivances are themselves invariably the work of mind. Call an organism a machine by all means, if you like; but where is the mind that made it, and I may add, that works it? Descartes, it will be remembered, was content to regard all the lower animals as simply automatic machines, comparable, though superior, to marionette dancers and flute-players such as those made afterwards by Vaucanson, which led Lamettrie to call even man a machine. But Descartes himself stopped short of this, on the ground that the complexity of human manifestations points to what Huxley has since called a conscious, as distinct from a mechanical, automatism. But the inconsequence of Descartes' reasoning has been generally allowed. It was open to him either to refer the greater variety of human life to the great complexity of the human brain, or knowing by direct experience that the human machine was a conscious automaton to infer that the simpler machineries of the lower organisms were conscious automata of a simpler type. The explanation of Descartes' inconsistent and illogical doctrine is to be found in the perplexities of the psychophysical problem, with which we shall have next to deal. Led by his fundamental analysis to insist on the complete disparateness of matter and mind, and led, therefore, to reject such hybrid notions as vital force, he saw no way of explaining the interaction of body and mind save by miracle,17 and naturally was averse to admitting such intervention any further than facts compelled him. His own consciousness, he thought, convinced him that man was a ‘mélange confus’ of body and soul; he did not feel forced to say the same of animals or of plants. But if we admit the inconsequence of Descartes' restriction of this concomitance of psychical and physical to man alone among animals; and if we admit, too, the invalidity of treating life as a specific form of energy,—then surely we are bound to assume this concomitance wherever we recognise life. To make my meaning clearer, let me first quote a sentence or two from an essay by a very distinguished botanist, and add one or two comments. The essay is by Professor Strasburger, of Jena, and his subject is Protoplasm and Sensibility. Referring to the analogy between organisation and machinery, he remarks: “For the structure of a machine, too, might be called its organisation; and the fact that, when provided with a store of energy, it can be started, by the opening of a valve, to perform work conformable to its structure—this property might be called its sensibility. But the living substance is entirely distinguished from the dead machine by the ability to provide itself with the energy needful for its work; to set itself in motion and keep itself going; to repair itself, within certain limits, the defects that may arise; and, above all, by the fact that it constructs itself. In short, an organismin contrast to the dead machineis a living machine, one that does not depend on external impulses for its movements, one that regulates its own course and continues going, as long as the environment will allow. Only through the hostility of this or through irreparable misfortune is it brought to a halt.”18 Now, I have said, that wherever we see a machine, we ask, Where is the mind that made it, and that works it? In the dead machine this mind is outside and independent; in the living machine, or organism, it is ‘inside,’ and so far identical. Living machine and conscious automaton are, then, strictly synonymous: whether we say life or whether we say consciousness, we equally imply the development and conservation of self by self through processes working counter to the downhill trend of the physical environment. Looking again at the dead machine, we may ask, What is it made for; what is the work that it is constructed to perform? To crush quartz, roll lead, grind flour, and so on, we are told, as the case may be. But what is the living machine made for? We must answer, be it plant, be it animal, be it man: For itself and for its kind, to live and to multiply. Once more, looking at the dead machine, we find the structure precedes and wholly determines the function; but in the organism, and especially when we take an ascending series of organisms into account, we find it truer to say the function, i.e. life, determines the structure.

And so we come to our second principle, that of subjective or hedonic selection.19 By way simply of illustrating this principle, and deferring meantime all question of its evolutional significance, let me try briefly to call up two or three examples. Take the passengers on a coach going through some glen here in Scotland: in one sense the glen is the same for them all, their common environment for the time being. But one, an artist, will single out subjects to sketch; another, an angler, will see likely pools for fish; the third, a geologist, will detect raised beaches, glacial striation, or perched blocks. Turn a miscellaneous lot of birds into a garden; a flycatcher will at once be intent on the gnats, a bullfinch on the pease, a thrush on the worms and snails. Scatter a mixture of seeds evenly over a diversified piece of country; heath and cistus will spring up in the dry, flags and rushes in the marshy, ground; violets and ferns in the shady hollows, gorse and broom on the hilltops. I am aware, of course, that thrushes and flycatchers, flags and heather, are products in large measure of natural selection, that is of what we have agreed to call a non-teleological factor. But I do not think this will be found to militate against these examples for my purpose. The complete unravelling of the two sets of factors, teleological and non-teleological, so as clearly to exhibit their respective shares in any given form is probably an impossible task. My concern is only to show that the two sets of factors are there, and that the teleological are indispensable. It will suffice then to observe that by the principle of subjective selection special environments are singled out by different individuals from the general environment common to all, and that so far there is not necessarily any competition. Two artists or two anglers may be in each other's way, but an artist and an angler will hardly incommode each other. A garden would still interest a flycatcher if there were neither pease nor cherries in it, provided the insects remained; whereas the bullfinch would at once forsake it. Natural selection as distinct from subjective selection comes into play only when two anglers contend for the same fish, two artists compete for the same prizes, when the early bird gets the worm that the later one must go without.

Let us next put this principle into shape and then we may consider its evolutional significance. Psychologically regarded, movements are determined by feeling: indifferent sensations, therefore, that occasion no feeling, lead to no movement in response; while the same presentation, if it occasion opposite feelings in two different individuals, will be followed by contrary movements. As I have put it elsewhere: “The twilight that sends the hen to roost sets the fox to prowl, and the lion's roar which gathers the jackals scatters the sheep. Such diversity in the movements, although the sensory presentations are similar, is due,” then, to the fact “that, out of all the manifold changes of sensory presentation which a given individual experiences, only a few are the occasion of such decided feeling as to become objects of possible appetite or aversion.”20 So we may formulate our principle; which granted, certain important consequences follow deductively when we connect it with well-known psychological laws. Specialisation means also concentration; the more restricted the lines of reaction, the more perfect these reactions become. The “Jack of all trades is master of none.” Thus subjective selection will determine definite variations as distinct from fortuitous ones, definite in the sense of bringing the individual into closer rapport with that portion of the general environment which it is selecting.

And now let us reflect how much these principles mean. Natural selection, it is allowed, is metaphorical. The common environment is not an agent, and selects as little as it conserves. Its tendency, if we consider it alone, is not to produce variations any more than to produce life; on the contrary, its tendency is towards uniformity and quiescence, as we may see in the dust and ashes to which in the end it reduces all. But in subjective selection there is nothing metaphorical; the agent here—so at least we must say as psychologists—is real, the source and type of all our conceptions of activity. I do not forget the psychophysical inquiry still pending; but that in any case has to accept psychological facts, being merely a theory about them. The agent then is real, not an abstraction; the selection likewise is real, not metaphorical. The individual positively selects what is pleasant, that is what conserves, for appetition; and negatively selects what is painful, and so detrimental, for aversion. To the remainder it is indifferent. By such selection is constituted its proper and specific environment. The origin of this kind of species, species of environments, at any rate seems due to a psychical, not to a physical, selection. Moreover, there is so far no struggle for existence, where “all subsists by elemental strife”: rather here, as the same poet has said, “All nature's difference keeps all nature's peace.”21

So far we may get by connecting our principles with the well-known psychological law, that concentration and practice perfect functions, and the corresponding physiological law, that function perfects structure. But there is another psychological generalisation with which I think we may connect them, and which imparts to them still further teleological significance. We have found Darwin exclaiming against “Lamarckian nonsense of a tendency to progression.” But if nonsense, it is nonsense of which many great thinkers have been guilty. We find it, of course, in “the wisest of wise Greeks, the Stagirite,” and in our day—spite of Darwin's disclaimer—it is still avowed by such leading biologists as Nägeli, Kölliker, and Virchow. No doubt Aristotle's conception of an internal perfecting principle was vague and lent itself to mystical interpretations. But I believe the progress of psychology will enable us some day to give it greater definiteness and a more assured foundation. Meanwhile time forbids any attempt to work further at this point now. But I will venture to quote a few sentences of my own published ten years ago, that may suffice to indicate what I mean: “How in the evolution of the animal kingdom do we suppose this advance from lower to higher forms of life to have been made? The tendency at any one moment is simply towards more life, simply growth; but this process of self-preservation imperceptibly but steadily modifies the self that is preserved. The creature is bent only on filling its skin; but in doing this as pleasantly as may be, it gets a better skin to fill, and accordingly seeks to fill it differently. Though cabbage and honey are what they were before, they have changed relatively to the caterpillar now it has become a butterfly. So, while we are all along preferring a more pleasurable state of consciousness before a less, the content of our consciousness is continually changing; the greater pleasure still outweighs the less, but the pleasures to be weighed are either wholly different or at least are the same for us no more. What we require, then, is … that to advance to the level of life on which pleasure is derived from higher objects shall on the whole be more pleasurable or less painful than to remain behind.”22 Now this condition seems provided, without any need for a clear prevision of ends or any feeling after improvement or perfection as such, simply by the waning of familiar pleasures and by the zest of novelty. In the midst of plenty it is usual to become more dainty and to make efforts to secure better fare, even though the old can be had without them. Exceptionally no doubt such circumstances lead to an opposite result, as we see in the degradation of most parasitic forms. But the principle of self-conservation seems sufficient to render this result exceptional.

Thus—even if there were no natural selection of variations fortuitously occurring, and even if there were no struggle for subsistence, still—the will to live, the spontaneous restriction of each individual to so much of the common environment as evokes reaction by its hedonic effects (with the increasing adaptation and adjustment that will thus ensue), and, finally, the pursuit of betterment to which satiety urges and novelty prompts,—these conditions, really implying no more than the most rudimentary facts of mind, will account for definite variations to an apparently unlimited extent. What is more, the variations so produced, even if there were no others, would furnish natural selection with an ample basis as soon as struggle for existence began. They would also remove or minimise one of the most formidable difficulties in the way of natural selection working alone—a difficulty which Mr. Herbert Spencer has had the credit of pointing out. It is easy to imagine a single variation which is at once useful, occurring fortuitously; and it is plain that natural selection will secure its survival. But when, as Darwin allows to be generally the case,23 utility depends on the coördination of a number of variations separately useless, then the chances against the simultaneous occurrence of these in due correlation increase at an alarming rate as the number of independent variants increases. Proportionally large drafts on time thus become requisite before such complex utilities can arise by lucky accident. We might say, I think, that not only are geologists accused of asking more time than according to the astronomer's facts the physical history of the earth will afford them, but that the demands of ultra-Darwinians like Weismann may expose them to a like charge on the part of geologists. Weismann long ago expressed the hope that at no distant date he would be able to consider this objection—I mean the difficulty of coördinations; but, so far as I am aware, he has not yet made good his promise.24

The mention of Weismann's name reminds me that many of you will be thinking of his famous doctrines of heredity and germ-plasm. If those doctrines are true, it will be said, acquired characters cannot be inherited, and the Lamarckian and other like teleological factors become, so far impossible. As to the truth of Weismann's properly biological doctrines I have no right to express an opinion, but there are some characteristics of his method on which I may remark. First, ‘acquired’ and ‘congenital’ do not seem to be terms whose meaning is independently fixed. If a character turns out to be inherited, Weismann thereupon feels entitled to call it congenital, even though he had previously in common with the rest of the world regarded it as acquired. Speech, for example, is an instance which he himself selected as an acquired capability, urging that if it were congenital the human infant ought to begin by talking. When it was pointed out that it does begin by “babbling articulate syllables,” the Weismannians urged, if Romanes may be trusted, that after all, “seeing of how much importance this faculty must always have been to the human species, it may very well have been a faculty which early fell under the sway of natural selection, and so it may have become congenital.”25 Secondly, it must be frankly admitted that in many instances in which acquired characters have been said to be inherited or might be expected to be inherited, the Weismannians have shown that nevertheless there is no such inheritance. But induction by simple enumeration is not sound logic. What the theory requires and assumes is the absolute non-inheritance of any acquired characters—a negative obviously difficult to establish. On the other hand, to overthrow the theory, it suffices if its opponents can shew that in any particular instances acquired characters are inherited. Several such instances have been adduced, and Weismann is at this minute devoting all his ingenuity to explaining these instances away. Lastly, in so doing he is driven not only to modify his theory, but to render it more and more cumbrous, complicated, and artificial. The more the body-plasm is eliminated as a medium of heredity, the more wonderful and miraculous the germ-plasm becomes. ‘Ids,’ ‘idants’, ‘biophores,’ ‘determinants,’ have an obviously teleological ring and yet are meant to make the teleological superfluous. They remind one of Mr. Spencer's speculations concerning organic evolution referred to in the last lecture; indeed, Weismann himself admits the resemblance. Yet, spite of the proverb that people in glass houses should not throw stones, we have the odd spectacle of Mr. Spencer vigorously bombarding Weismann's bulwarks, quite unconscious of the fact that he is thereby seriously damaging his own.

We seem warranted, then, in concluding, with Darwin himself, and Weismann notwithstanding, that natural selection without teleological factors is not adequate to account for biological evolution; and further, that such teleological factors imply not a nondescript force called vital, but a psychical something endowed with feeling and will. Finally, recalling our survey of evolution in the wider sense, we have seen that, unless the cosmos itself is to be regarded as a finite and fortuitous variation persisting in an illimitable chaos, we must refer its orderliness and meaning to an indwelling, informing Life and Mind. But the problem of the relation of Mind to Mechanism still remains.

  • 1.

    Origin of Species, sixth edition, last sentence.

  • 2.

    Cf. Romanes, Darwin and After Darwin, vol. ii, ch. 1.

  • 3.

    Origin of Species, edition 1815, t. i, p. 181.

  • 4.

    Non-teleological, that is, within the range of strictly biological ideas.

  • 5.

    I refer, of course, to his contention that the moral and intellectual nature of man cannot be explained by natural selection. See his Darwinism, ch. xv.

  • 6.

    Cf. Osborn, From the Greeks to Darwin: an Outline of the Development of the Evolution Idea, 1895, p. 236.

  • 7.

    Cf. Osborn, From the Greeks to Darwin: an Outline of the Development of the Evolution Idea, 1895, p. 196.

  • 8.

    Which, by the way, it would seem Lamarck did not hold. Cf. Osborn, From the Greeks to Darwin: an Outline of the Development of the Evolution Idea, 1895, p. 237.

  • 9.

    Origin of Species, sixth edition, p. 421.

  • 10.

    Origin of Species, p. 162,

  • 11.

    The mysticism now commonly associated with this conception seems mainly due to the neo-Platonists and the Scholastics.

  • 12.

    Note xii.—For illustrative instances see the Evening Lecture on “The Movements of Plants,” delivered at the Glasgow meeting of the British Association, 1901, by Francis Darwin, F.R.S., reported in Nature, vol. lxv. p. 40; also (by the same author) “The Statolith Theory of Geotropism,” Nature, vol. lxvii. p. 571; also Sinnesorgane in Pflanzenreich zur Perception mechanische Reize, by Professor Habelandt, 1901.

  • 13.

    Encyclopœdia Britannica, article Psychology, pp. 42 f.

  • 14.

    Primary Factors of Organic Evolution, 1896, p. 514.

  • 15.

    Cf. Spinoza, his Life and Philosophy, by sir F. Pollock, pp. 221 ff.

  • 16.

    Art. Psychology, Encyclopœdia Britannica, vol. xx, 1886.

  • 17.

    I do not mean that Descartes regarded the union of body and mind in man as continuously maintained by special Divine intervention. His followers were, but he was not, an occasionalist, spite of all Hamilton's, contentions to the contrary (edition of Reid, p. 961). This union was for Descartes only ‘hyperphysical’ in the sense of being a unique fact, a ‘negative instance,’ as Kuno Fischer aptly calls it. The following extract from a letter of Descartes to Arnauld seems decisive: Que l'esprit qui est incorporel puisse faire mouvoir le corps, il n'y a ni raisonnement, ni comparaison tirée des autre choses qui nous le puisse apprendre, mais néanmoins nous n'en pouvons douter, puisque des expériences trop certaines et trop évidentes nous le font connaitre tons les jours manifestement. Et il faut bien prendre garde que cela est une des choses qui sont connues par elle-mêmes, et que nous obscurcissons toutes les fois que nous voulons les expliquer par d'autres. Œuvres, Cousin's edition, x, p. 161.

  • 18.

    Das Protoplasma und die Reizbarkeit, 1891, pp. 24 f.

  • 19.

    There is, I now find, some considerable resemblance between this principle and one that was set forth some ten years later by Professors Lloyd Morgan, Osborn, and Baldwin, and on which the last mentioned has conferred the very ambiguous title of Organic Selection. A clear account of this theory will be found in two Appendices, A and B, of Professor Baldwin's Development and Evolution, 1902 (pp. 335-371), consisting of extracts from the writings of its first propounders and others who have since adopted it. See Note xiii.

  • 20.

    Encyclop™dia Britannica, article Psychology. p. 42.

  • 21.

    Pope, Essay on Man, i, 169; iv, 56.

  • 22.

    Encyclop™dia Britannica, article Psychology, p. 72.

  • 23.

    Cf. Origin of Species, sixth edition, pp. 178 fin.

  • 24. Note xiv.—Within the last six or seven years—and particularly in his latest book on “Germinal Selection as a source of determinate variation—Weismann has amply redeemed his promise to deal with the questions of co-adaptation and the transmission of functionally-produced modifications. To the surprise of everybody he begins by admitting that after all “the Lamarckians were right in maintaining that what has so far alone borne the denomination of Natural Selection is inadequate to explain the phenomena.” “Something is still wanting to the Selection of Darwin and Wallace. … There is still a hidden secret to be discovered.” The selection of accidental variations will not suffice: a “profounder connection must exist between the utility of a variation and its appearance, or in other words, the direction of the variation of a part must be determined by utility.” To Darwin's ‘personal selection’ as Weismann calls it—or the selection of individuals brought about by their struggle for existence—to Roux's “histonal selection,” due to the struggle for food and room of parts within the organism, there must be added ‘germinal selection,’ the result of the struggle for food among the biophores, determinants, etc., which on his theory constitute the germ. So confident is Weismann of the sufficiency of natural selection, when thus extended, that he indulges the hope of a speedy reconciliation and amalgamation of the hitherto conflicting views; accordingly he holds out the olive branch to his quondam opponents and invites them to join-with him in building further on the newly-laid foundation. So far the invitation has met with no response. The general attitude of biologists towards Weismann's work is fairly represented in the following conclusion of one of his ablest and most impartial critics:— “Nous crayons avoir montré qu'il est bâti d'hypothèses fragiles, invraisemblables, et, tout en rendant justice au talent do son architecte, noun conseillons de l'admirer de loin et de construire ailleurs” (Delage, Structure du Protoplasma, etc., 1895, p. 837).
  • 25.

    Darwin and after Darwin, vol. ii, p. 336.