The philosophy of biology

Front matter

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C. F. CLAY, Manager

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Chapter I Page

the conceptual world ...... X

Argument. — The conscious organism is one that acts. Its consciousness of an external world is not simply the result of the stimuli made by that world on its organs of sense, for it becomes fully aware only of those stimuli which result in deliberated bodily activity. This awareness of an outer world on which it acts is the perception of the organism. Its consciousness is an intensive multiplicity. This multiplicity is arbitrarily dissociated, for convenience' sake, by the mental organisation, which confers extension and magnitude and succession on those aspects of consciousness which it arbitrarily dissociates from each other. Our notion of space is an intuitive one and depends on our modes of bodily exertion. Our notions of motion and continuity are also intuitive ones, and they cannot be represented intellectually, but we can approximate to them by the methods of the infinitesimal calculus. Mathematical time is only a series of standard events which 'punctuate our duration. Duration is the accumulated existence and experience of the organism. We cannot prove intellectually that there is a world external to our consciousness, but that this world exists is a conviction intuitively held.

Chapter II The Organism As A Mechanism

Argument. — If the organism is a physico-chemical mechanism its activities must conform to the two principles of energetics : the law of conservation of energy and matter, and the law of entropyincrease. They conform strictly to the law of conservation. The law of the degradation of energy is true of our experience of inorganic nature, but we can show that it cannot be universally true. Inorganic processes are irreversible ones, and they proceed

XI xii in one direction only, and in them energy is degraded. Organic processes, that is, the processes carried on in the generalised organism, are irreversible ; or, at least, there is a tendency for them to be carried on without necessary dissipation of energy.

Chapter III

Argument. — If the organism is investigated by the methods of physical and chemical science, nothing but physico-chemical activities can be discovered. This is necessarily the case, since methods which yield physico-chemical results only are employed. The physiologist makes an analysis of the activities of the organism, and he reduces these activities to certain categories ; although all attempts completely to describe the functioning of the organism solely in terms of physical and chemical reactions fail. In addition to the reactions which make up the functioning of an organ or organ-system, there is direction and co-ordination of these reactions. The individual physico-chemical reactions which occur in the functioning of the organism are integrated, and life is not merely these reactions, but also their integration.

Chapter IV

Argument. — The notion of the organism as a physico-chemical mechanism is a deduction from the methods of physiology, and not from its results. The notion of vitalism is a natural or intuitive one. The historic systems of vitalism assumed the existence of a spiritual agency in the organism, or of a form of energy which was peculiar to the activities of the organism. Modern investigation lends no support to either belief. But the study of the organism as a whole, that is, the study of developmental processes, or that of the organism acting as a whole, afford a logical disproof of pure mechanism. It shows that there cannot be a functionality, in the mathematical sense, between the inorganic agencies that affect the whole organism and the behaviour or functioning of the whole organism. Mechanism is only suggested in the study of isolated parts of the organism. We are compelled toward the belief that there is an agency operative in the activities of the organism which does not operate in purely inorganic becoming. This is the Vital Impetus of Bergson, or the Entelechy of Driesch.

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Chapter V Page

Argument. — The concept of the organic individual is one which is arbitrary, and is convenient only for purposes of description.

Life on the earth is integrally one. Personality is the intuition of the conscious organism that it is a centre of action, and that all the rest of the universe is relative to it. The individual organism, regarded objectively, is an isolated, autonomous constellation, capable of indefinite growth by dissociation, differentiation, and re-integration. This growth is reproduction. The dissociated part reproduces the form and manner of functioning of the individual organism from which it has proceeded. The offspring varies from the parent organism, but it resembles it much more than it varies from it. There are therefore categories of organisms in nature the individuals of which resemble each other more than they resemble the individuals belonging to other categories : these are the elementary species. Hypotheses of heredity are corpuscular ones, and are based on the physical analogy of molecules and atoms. The concept of the species is a logical one. The organism is a phase in an evolutionary or a developmental flux, and the idea of the species is attained by arresting this flux.

CHAPTER VI TRANSFORMISM 2o8

Argument. — A reasoned classification of organisms suggests that a process of evolution has taken place. It suggests logical relationships between organisms, while the results of embryology and palaeontology suggest chronological relationships. Yet this kinship of organisms might only be a logical, and not a material one. Evolution may have occurred somewhere, but it might be argued that the ideas of species have generated each other in a Creative Thought. But transformism may be produced experimentally, and so science has adopted a mechanistic hypothesis of the nature of the process. Transformism of species depends on the occurrence of variations, but these arise spontaneously and independently of each other, and they must be co-ordinated. This co-ordination of variations cannot be the work of the environment. Variations are cumulative, and they exhibit direction, and this direction is either an accidental one, or it is the expression of an impetus or directing agency in the varying organism itself The problem of the cause of variation is only a pseudo-problem

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Chapter VII The Meaning Of Evolution

Argument. — If we assume the existence of an evolutionary process, the results of morphology, embryology, and palaeontology ought to enable us to trace the directions followed during this process. But these results are still so uncertain that they indicate only a few main lines of transformism. Phylogenetic trees are largely conjectural in matters of detail. Evolution has resulted in the establishment of several dominant groups of organisms — the metatrophic bacteria, the chlorophyllian organisms, the arthropods, and the vertebrates. Each of these groups displays certain characters of morphology, energy-transformation, and behaviour ; and a certain combination of characters is concentrated in each of the groups. But there is a community of character in all organisms which have arisen during the evolutionary process. The transformation of kinetic into potential energy is characteristic of the chlorophyllian organisms. The utilisation of potential energy, and its conversion into the kinetic energy of regulated bodily activity, by means of a sensori-motor system, is characteristic of the animal. The bacteria carry to the limit the energy-transformations begun in the tissues of the plants and animals. Immobility and unconsciousness characterise the plant, mobility and consciousness the animal. Animals indicate two types of actions — intelligent actions and instinctive actions. Instinctive activity involves the habitual exercise of modes of action that have been inherited. Intelligent activities involve the exercise of modes of action that are not inherited, but which are acquired by the animal during its own lifetime, and are the results of perceptions which show the animal that its activity is relative to an outer environment.

Chapter VIII The Organic And The Inorganic

Argument. — A strictly mechanistic hypothesis of evolution compels us to regard the organic world, and the inorganic environment with which it interacts, as a physico-chemical system. All the stages of an evolutionary process must therefore be equally complex : they are simply phases, or rearrangements, of the

elements of a transforming system. The physics on which these mechanistic hypotheses were based was that of a discontinuous, granular, Newtonian universe, that is, one consisting of discrete particles, or mass-points, attracting or repelling each other with forces which are functions of the distances between them. It was a spatially extended system of parts. Therefore at all stages in an evolutionary process, or one of individual development, the elements of the system constitute an extensive manifoldness, and the obligation of mechanistic hypotheses of evolution and development to accept this view has shaped modern theories of heredity. Life is an intensive manifoldness, but in individual or racial evolution this intensive manifoldness becomes an extensive manifoldness. Life is a bundle of tendencies which can co-exist, but which cannot all be fully manifested, in the same material constellation, therefore these tendencies become dissociated in the evolutionary process. In this dissociation there is direction and co-ordination, which are the Vital Impetus of Bergson, or the Entelechy of Driesch.

Entelechy is an elemental agency in nature which we are compelled to postulate because of the failure of mechanism. It is not spirit, nor a form of energy, but the direction and co-ordination of energies. There is a sign, or direction of inorganic happening which absolutely characterises the processes which are capable of analysis by physico-chemical methods of investigation, and the result of this direction of inorganic happening is material inertia. Y et this direction cannot be universal : it must be evaded somewhere in the universe. It is evaded by the organism.

The problem of the nature of life is only a pseudo-problem.

MATHEMATICAL AND PHYSICAL NOTIONS ....

Infinity and the notion of the limit. Functionality. Frequency distributions and probability. Matter, force, mass, and inertia. Energy-transformations. Isothermal and adiabetic transformations. The Carnot engine and cycle. Entropy. Inert matter.

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Chapter I

Let us suppose that we are walking along a street in a busy town ; that we are familiar with it, and all the things that are usually to be seen in it, so that our attention is not likely to be arrested by anything unusual ; and let us further suppose that we are thinking about something interesting but not intellectually difficult. In these circumstances all the sights of the town, and all the turmoil of the traffic fail to impress us, though we are, in a vague sort of way, conscious of it all. Electric trams approach and recede with a grinding noise ; a taxicab passes and we hear the throb of the engine and the hooting of the horn, and smell the burnt oil ; a hansom comes down the street and we hear the rhythmic tread of the horse's feet and the jingle of the bells ; we pass a florist’s shop and become aware of the colour of the flowers and of their odour ; in a cafe a band is playing “ ragtime.” There are policemen, hawkers, idlers, ladies with gaily coloured dresses and hats, newsboys, a crowd of people of many characteristics. It is all a flux of experience of which we are generally conscious without analysis or attention, and it is a flux which is never for a moment quite the same, for everything in it melts and flows into everything else. The noise of the tram-cars is incessant, but now and then it becomes louder ; the music of the orchestra steals imperceptibly on our ears and as imperceptibly fades away ; the smell of the flowers lingers after we pass the shop, and we do not notice just when we cease to be conscious of it ; the rhythm of the ragtime continues to irritate after we have ceased to hear the band — all the senseimpressions that we receive melt and flow over into each other and constitute our stream of consciousness, and this changes from moment to moment without gap or discontinuity. It is not a condition of “ pure sensation,” but it is as nearly such as we can experience in our adult intellectual life.

It is easy to discover that many things must have occurred in the street which did not affect our full consciousness. We may learn afterwards that we have passed several friends without recognising them ; we may read in the newspapers about things that happened that we might have seen, but which we did not see ; we may think we know the street fairly well, but we find that we have difficulty in recalling the names of three contiguous shops in it ; if we happen to see a photograph which was taken at the time we passed through the street we are usually surprised to find that there were many things there that we did not see. Why is it, then, that so much that might have been perceived by us was not really perceived ? We cannot doubt that everything that came into the visual fields of our eyes must have affected the terminations of the optic nerves in the retinas ; the complex disturbances of the air in the street must have set our tympanic membranes in motion; and all the odoriferous particles inhaled into our nostrils must have stimulated the olfactory mucous membranes. In all these cases the stimulation of the receptor organs must have initiated nervous impulses, and these must have been propagated along the sensory nerves, and must have reached the brain, affecting masses of nerve cells there. Nothing in physiology seems to indicate that we can inhibit or repress the activity of the distance sense-receptors, visual, auditory, and olfactory, with their central connections in the brain ; they must have functioned, and must have been physically affected by the events that took place outside ourselves, and yet we were unconscious, in the fullest sense of this term, of all this activity. Why is it, then, that our perception was so much less than the actual physical reception of external stimuli that we must postulate as having occurred ? Sherlock Holmes would have said that we really saw and heard all these things although we did not observe them, but the full explanation involves a much more careful consideration of the phenomena of perception than this saying indicates.

There is, of course, no doubt that we did see and hear and smell all the things that occurred in the street during our aimless peregrination, that is, all the things which so happened that they were capable of affecting our organs of sense. This is true if we mean by seeing and hearing and smelling merely the stimulation of the nerve-endings of the visual, auditory, and olfactory organs, and the conduction into the brain of the nervous impulses so set up. But merely to be stimulated is only a part of the full activity of the brain ; the stimulus transmitted from the receptor organs must result in some kind of bodily activity if it is to affect our stream of consciousness. Two main kinds of activity are induced by the stimulation of a receptor organ and a central ganglion, (i) those which we call reflex actions, and (2) those actions which we recognise as resulting from deliberation. We must now consider what are the processes that are involved in these kinds of neuro-muscular activity.

The term “ reflex action ” is one that denotes rather a scheme of sensori-motor activity than anything that actually happens in the animal body ; it is a concept that is useful as a means of analysis of complex phenomena. In a reflex three things happen, (i) the stimulation of a receptor organ and of the nerve connecting this with the brain, (2) the reflection, or shunting, of the nervous impulse so initiated from the terminus ad quem of the afferent or sensory nerve, to the terminus a quo of the efferent or motor nerve, and (3) the stimulation of some effector organ, say a motor organ or muscle, by the nervous impulse so set up. The simplest case, perhaps, of a reflex is the rapid closure of the eyelids when something, say a few drops of water, is flicked into the face. Stated in the way we have stated it the simple reflex does not exist. In the first place, it is a concept based on the structural analysis of the complex animal where the body is differentiated to form tissues — receptor organs, nerves, muscles, glands, and so on. But a protozoan animal, a Para?ncecium for instance, responds to an external stimulus by some kind of bodily activity, and yet it is a homogeneous, or nearly homogeneous, piece of protoplasm, and this simple protoplasm acts at the same time as receptor organ, conducting tissue or nerve, and effector organ. In the higher animal certain parts of the integument are differentiated so as to form visual organs, and the threshold of these for light stimuli is raised while it is lowered for other kinds of physical stimuli. Similarly other parts of the integument are modified for the reception of auditory stimuli, becoming more susceptible for these but less susceptible for other kinds of stimuli than the adjacent parts of the body. Within the body itself certain tracts of protoplasm are differentiated so that they can conduct molecular disturbances set up in the receptor organs in the integument better than can the general protoplasm ; these are the nerves. Other parts are modified so that they can contract or secrete the more easily ; these are the muscles and glands. The conception of a reflex action, as it is usually stated in books on physiology, therefore includes this idea of the differentiation of the tissues, but all the processes that are included in the typical reflex are processes which can be carried on by undifferentiated protoplasm.

It is also a schematic description that assumes a simplicity that does not really exist. As a rule a reflex is initiated by the stimulation of more than one receptor organ, and the impulses initiated may thus reach the central nervous system by more than one path. There is no simple shunting of the afferent impulse from the cell in which it terminates into another nerve, when it becomes an efferent impulse ; but, instead of this, the impulse may “ zigzag ” through a maze of paths in the brain or spinal cord connecting together afferent and efferent nerves and ganglia. Further, the final part of the reflex, the muscular contraction, is far from being a simple thing, for usually a series of muscles are stimulated to contract, each of them at the right time and with the right amount of force, and every contraction of a muscle is accompanied by the relaxation of the antagonistic muscle. There are muscles which open the eyelids and others which close them, and the cerebral impulse which causes the levators to contract at the same time causes the depressors to relax.

It is quite necessary to remember that the simple reflex is really a process of much complexity and may , involve many other parts and structures than those to which we immediately direct our attention. But leaving aside these qualifications we may usefully consider the general characters of the reflex, regarding it as a common, automatically performed, restricted bodily action, involving receptor organ, central nervous organ, and effector organ. There are certain kinds of external stimuli that continually affect our organs of sense, and there are certain kinds of muscular and glandular activity that occur “ as a matter of course,” when these stimuli fall on our organs of sense. The emanation from onions or the vapour of ammonia causes our eyes to water ; the smell of savoury food causes a flow of saliva ; and anything that approaches the face very rapidly causes us to close the eyes. Reflexes are, in a way, commonly occurring, purposeful and useful actions, and their object is the maintenance of a normal condition of bodily functioning.

We dare hardly say that the simple reflex is an unconsciously performed action, although we are not conscious, in the fullest sense of the term, of the reflexes that habitually take place in ourselves. But even in the decapitated frog, which moves its limbs when a drop of acid is placed on its back, something, it has been said, akin to consciousness may flash out and light up the automatic activity of the spinal cord. We must not think of consciousness as that state of acute mentality which we experience in the performance of some difficult task, or in some keenly appreciated pleasure, or in some condition of mental or bodily distress ; it is also that dimly felt condition of normality that accompanies the satisfactory functioning of the parts of the bodily organism. But this dim and obscure feeling of the awareness of our actions is easily inhibited whenever what we call intellectual activity proceeds.

Much of the stimulation of our receptor organs is of this generally occurring nature, and we are not aware of it although the stimuli received are such as to induce useful and purposeful bodily activity. In walking along the street we automatically avoid the people, and the other obstacles that we encounter, by means of regulated movements of the body and limbs, but this is activity that has become so habitual and easy that we are hardly aware of it, and not at all, perhaps, of the physical stimuli which induce it. But not only do we receive stimuli which are reflected into bodily actions without our being keenly aware of this reception, but we also receive stimuli which do not become reflected into bodily activity. It is, Bergson suggests, as if we were to look out into the street through a sheet of glass held perpendicularly to our line of sight ; held in this way we see perfectly all that happens in front of us, but when we incline the glass at a certain augle it becomes a perfect reflector and throws back again the rays of light that it receives. This is, of course, a physical analogy, and no comparison of material things with psychical processes can go very far, but in a way it is more than an analogy. In our indolent absorbed state of mind we do not as a rule see the objects which we are not compelled to avoid, and which do not, in any way, influence our immediate condition of bodily activity. The optical images of all these things are thrown upon our retinas and are, in some way, thrown or projected upon the central ganglia, but there the series of events comes to an end, for the images are not reflected out towards the periphery of the body as muscular actions. We cannot doubt that this is why we do not perceive all

* the stimulation of our organs of sense that we are sure that take place. These stimuli pass through us, as it were, unless they are reflected out again as actions. In this reflection, or translation of neutral into muscular activity, perceptions arise .

But even then perception need not arise. It does not, as a rule, accompany the automatically performed reflex action, because the latter is the result of intra-cerebral activities that have become so habitual that they proceed without friction. There are innumerable paths in the brain along which impulses from the receptor organs may pass into the motor ganglia, but in the habitually performed reflex actions these paths have been worn smooth, so to speak. The images of objects which are perceived over and over again by the receptor organs glide easily through the brain and as easily translate themselves into muscular, or some other kind of activity. The things that matter in the life of an animal which lives “ according to nature ” are cyclically recurrent events in which, after a time, there is nothing new. Most of them proceed just as well in the animal deprived of its cerebral hemispheres by operation as in the intact cerebrate animal. In the performance of actions of this kind the organism becomes very much of an automaton.

Let something unusual happen in the street while we are walking through it — a runaway horse, or the fall of an overhead “ live ” wire, for instance, something that has seldom or never formed part of our experience, and something that may have an immediate effect on us as living organisms. Then perception arises at once because the stimulation of our organs of sense presents us with something which is unfamiliar, and yet not so unfamiliar that it does not recall from memory, or from derived experience, Reminiscences of the

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images of somewhat similar things, and of the effects of these. The train of events that now proceeds in our central nervous system becomes radically different from that which proceeded in our former, rather aimless, series of actions. The stimuli no longer pass easily through the “ lower ” ganglia of the brain, but flash upwards into the cortical regions, where they become confronted with the possibility of innumerable alternative paths and connections with all the parts of the body. They waver, so to speak, before adopting one or other, or a combination of these paths ; there is hesitation, deliberation, and finally choice of a path, with the result that a series of muscular organs become inervated and motor actions, of a type more or less competent to the situation in which we find ourselves, are set up. In this hesitation and deliberation perception arises. It is when the animal may act in a certain way as the result of a stimulus which is not a continually recurrent one, but at the same time may refrain from acting, or may act in one of several different ways, that perception of external things and their relations arises.

That is to say, we perceive and think because we act. We do not look out on the environment in which we are placed in a speculative kind of way, merely receiving the images of things, and classifying and remembering them, while all the time we are passive in so far as our bodily activities are concerned. If the results of modern physiology teach us anything in an unequivocal way they teach us this — that the organs of activity, muscles, glands, and so on, and the organs of sense and communication, are integrally one series of parts, and that apart from motor activity nervous activity is an aimless kind of thing. It is because we act that we think and disentangle the images of things presented to us by our organs of sense, and subject all that is in the stream of consciousness to conceptual analysis.1

That is to say, in thinking about the flux of consciousness we decompose it into what we regard as its constituent parts, and we confer upon these parts separate existence in space and time. But it is clear that none of the things which we thus regard as the elements of our consciousness has any real existence apart from the others. The smell of the flowers and that of the burnt oil interpenetrate in our consciousness of the stimulation of our olfactory organs just as do the jingle of the cab bells, the music of the orchestra, and the throb of the motor car in the impressions transmitted by our auditory organs. It is difficult to see that all these things, with the multitude of other things which we perceive, constitute a “ multiplicity in unity/' that is an assemblage of things which are separate things, but which do not lie alongside each other in space and mutually exclude each other, but which are all jammed into each other, so to speak. It is easy to see that we are conscious of a heterogeneity, and whenever we think of this multitude of things it seems natural that we should separate them from each other. The stream of our consciousness is so complex that we cannot attend to it all at once, not even to the few things that we have picked out in our example. If we concentrate our attention on any part, or rather aspect of it, all the rest ceases to exist, or rather we agree to ignore it, and this very concentration of thought upon one part of our experience isolates it from all the rest. To a certain extent the analysis of the complex of sensation is the result of the work of different receptor organs ; certain

1 All this is, of course, the argument of Bergson’s earlier books, Matiere et Memoire and Donnies immidiates de la Conscience.

fields of energy, which we call light, radiation, etc., affect the nerve-endings in the retina ; chemically active particles in the atmosphere affect the nerve-endings in the olfactory membranes ; and rapidly repeated changes of pressure in the atmosphere (sound vibrations) affect the auditory organs in the internal ear, and so on. But this reception of different stimuli by different receptor organs exists only in the higher animal ; there are no specialised sense organs in a Paramecium, for instance, and the whole periphery of the animal must receive ^ all these different kinds of external stimuli at once.

The specialisation of its receptor organs in the higher animal is rather the means whereby the organism becomes more receptive of its environment, than the means whereby it analyses that environment. This analysis is the work of animal.

Suppose that we draw a curve AB freehand with a single undivided sweep of the pencil. By making a certain assumption — that the curve which we drew was one that might be regarded as cyclical, that is, might be repeated over and over again — we can subject it to harmonic analysis. We can decompose it into a number of other curves {CD, EF, etc.), each of which is a separate “ wave ” rising above and falling below the axis OX in a symmetrical manner. If we draw any vertical line MN cutting these curves, we shall find that the distance between the axis OX and the