In the preceding lectures I have endeavoured to survey and define the general conceptions which are in use in the physical, biological, and psychological branches of knowledge. In this concluding lecture of the first course I wish to draw attention to the very imperfect manner in which it is alone possible to apply these general conceptions.
I began the lectures by discussing the difference between biological and ordinary physical conceptions. The difference between these conceptions is such as to produce a separation between the biological and physical sciences, so that the world as interpreted in the biological sciences seems like a different one from that of the physical sciences, though the two worlds are actually the same. As I endeavoured to show, we cannot possibly describe or interpret biological phenomena in terms of ordinary physical conceptions, but we might conceivably be able to extend the use of biological interpretation so that it applied to what we at present regard as inorganic; and the new developments of physics seem to be to some extent tending in this direction. Apart altogether from this latter possibility, however, I wish now to point out the inherent imperfection of the biological interpretation, and the fact that in biology it is apparently necessary to supplement biological by physical conceptions.
When we consider the co-ordination or wholeness which shows itself in the phenomena of life, it seems as if this can only show itself in contrast to mechanical chaos. As we have seen, it is only through the application of accurate physical and chemical methods of measurement that physiological co-ordination is gradually revealed. But these methods seem to assume the existence of the mechanical chaos which, as we have also seen, is an essential feature of the Newtonian conception of the inorganic world.
Let us take examples in illustration of this statement. We begin to realize the co-ordination manifested in the phenomena of breathing when we determine at different times and under different conditions the pressure of carbon dioxide in the air contained in the lung alveoli, and find that this pressure is maintained nearly constant in spite of variations in the times and conditions. But what is it that we are measuring when we measure the pressure of carbon dioxide? We are simply measuring the pressure produced through mechanical bombardment by free molecules of carbon dioxide moving chaotically. The fact that they are moving chaotically seems to be demonstrated by the fact that as regards the pressure which they produce they follow the gas laws, of which the physical basis is that the molecules are in absolutely chaotic movement, colliding with one another and with the walls of the lung alveoli in every possible way. In spite, however, of the fact that far more molecules of carbon dioxide are being given off from the alveolar walls than are absorbed, the pressure of carbon dioxide in the alveolar air is kept nearly constant by the lung ventilation.
It is only in the maintenance of this constancy that organic co-ordination of respiration manifests itself; but the constancy is maintained by mechanical pumping of air into and out of the lungs. This pumping is under general organic control; nevertheless we regard it as in itself a mere mechanical process. Thus it is only in the general regulation of mechanical processes that the physiological co-ordination or wholeness manifests itself. It seems to be a purely mechanical factor, namely, the bombardment pressure of carbon dioxide molecules, that is regulated; and apart from the fact that we can distinguish and measure this mechanical factor, the existence of the physiological co-ordination would be hidden from us. To discover the co-ordination we have had to apply exact physical and chemical methods and conceptions. We have had, moreover, to assume that mechanical chaos prevails within the air which is concerned in respiration, and but for this assumption the co-ordination would have no definite meaning for us. The co-ordination is a co-ordination of what is in other respects mechanical chaos, so that the existence of this chaos in matters of detail is complementary to the distinctively biological fact of the existence of co-ordination in the phenomena observed. It is only, therefore, in part, or imperfectly, that we can apply the biological conception of co-ordination. We need to assume the presence of a mechanical chaos which is only in part controlled organically.
When we consider other physiological activities in which organic control is manifested, we find the same apparent coincidence between mechanical chaos and organic unity. Thus in the case of excretion of water by the kidneys we have to assume that in the blood-plasma the molecules of water exist in the state of mechanical chaos characteristic of liquids. If they were not controlled in some way, these molecules would pass through the secreting membrane at a rate determined solely by mechanical factors. It is through the fact of their not doing so in spite of the mechanical chaos that we recognize the existence of organic regulation of the blood-plasma. To take still another instance, a reflex nervous response has, by itself, the character of a mere mechanical response to a suitable stimulus; and evidently it tends to act in this way, though on closer study we find that it is inhibited or reinforced in various ways which show that it is also under organic control. Thus chaotic mechanical conditions are here, again, associated with organic unity.
In the maintenance of bodily structure we find the same association between organic control and mechanical chaos. The structure is constantly tending to disintegrate by physical and chemical processes, and it is only in the control of this tendency that organic morphological unity manifests itself.
Apart from the existence of the chaos of physico-chemical conditions, we cannot imagine the existence of active biological co-ordination. Thus the existence of a world of life seems also to imply the existence of physico-chemical conditions. If, by some automatic process, the molecules concerned in the living structure and environment of an organism were kept in a mean normal position without any physico-chemical disintegration tending to occur, there would be no active life, and the very conception of life would have lost its meaning.
We might also imagine that the individual molecules concerned in life-processes, instead of tending to move chaotically, moved as if they were listening to music and taking part in an orderly dance, expressing in its movements the co-ordination of the life-processes. This is, in fact, an approximation to how the molecules more intimately concerned in living structure seem to behave, their movements becoming less and less chaotic as they approach each centre of living activity. With molecules moving in this manner, the gas-laws, and their extensions to liquids and solids, would cease to apply, since organic co-ordination would interfere too much with mechanical chaos; but even in an orderly dance the fundamental physical laws are still distinguishable, and apart from inertia and gravitation the measures of the dance would have no meaning.
It was pointed out in previous lectures that when living organisms come into physiological relation with one another their lives may, together, still form an organic unity, as in the case of the constituent cells of a compound organism. It seems equally true, however, that the life of one organism may be to that of another no more than part of the mechanical chaos in the presence of which the life of either organism is realized. The organic unity of a higher organism is shown clearly in the activities by which it resists and may become practically immune to infection by lower organisms. These activities are on a par with any other physiological activities which seem to resist the mechanical chaos which is everywhere at hand. The invading organism is killed and thrown out, or else succeeds in killing the invaded organism, just as the latter may be killed through failure to resist the mechanical chaos of its environment, as when the stomach, lungs, heart, kidneys, or sense-organs fail to act effectively. Even if we regard atoms as being essentially living organisms, the mechanical chaos remains.
The life of an organism seems thus to be a constant struggle against what, for it, are chaotic conditions, whether the chaos be that of ordinary physico-chemical conditions, or that of organisms struggling blindly with one another. We can see clearly the organic unity of its life, and the study of this kind of unity constitutes the science of biology. But we can see equally clearly the chaotic conditions in which by themselves there seems to be no unity; and the study of the unity is necessarily also the study of the chaotic conditions. If, as in practical medicine, we wish to aid the organism in its struggle, we must not only study in every accessible detail the manner in which the organic unity of the organism's life is maintained, and restored after disturbance, but we must also study the chaotic physico-chemical conditions of the environment, so that by amending them we can aid the organism in its struggle, and aid it in recovery from injury already done. Knowledge of physics and chemistry, and of hostile organisms, is thus an integral part of knowledge of medicine. The chaotic conditions never recede from our view; they seem always evident.
On the plane of psychological experience we find, similarly, that though, in conscious behaviour, psychological or spiritual continuity of this behaviour at different times is evident enough, discontinuity is also always present. The behaviour of no person is consistently rational in the furtherance of what he is interested in. What might have been foreseen is commonly not foreseen, and what might have been remembered is equally commonly not remembered. Apart from this, however, interest and values are not clearly defined in detail, since, like biological unity, they include an element of mechanical chaos, so that perceptions and voluntary actions are correspondingly imperfect. We are always “learning,” and it is only in the struggle of learning and acting on new insight that psychological unity shows itself, just as it is only in the struggle with physico-chemical chaos that biological unity shows itself. In so far as a person does not learn, and merely repeats previous imperfect perceptions and so makes correspondingly imperfect responses to them, he becomes psychologically or spiritually inert, since there is to this extent nothing but aimless succession in his actions.
Much of a person's behaviour is, though highly and delicately co-ordinated, mere repetition of previous behaviour, with no improvement in the successive repetitions. The acts of writing, walking, riding a bicycle, or steering a motor-car on an open road, are, for instance, very delicately co-ordinated, and could not be imitated by any machine. But when once they have been learnt they are repeated without mental effort and with no continuous improvement, however imperfect they may be. Thus their details do not any longer enter into conscious behaviour, any more than do the details of respiration, circulation, secretion, and other physiological activities. Nevertheless the imperfection with which bodily activities are carried out is part of the general imperfection of conscious behaviour, and responsibility for that imperfection is part of the responsibility for other imperfections in conscious behaviour. The fact that we are continuously responsible for our own bodily health and efficiency, as well as for those of our neighbours, is being realized more and more as civilization advances.
All around us we see disease and death—facts which, in themselves, we seem unable to interpret from a psychological standpoint. Disease, crime, death, and birth are matters so familiar to us that the deep mystery which surrounds them is scarcely realized; but their existence ought to serve as a constant reminder to us of the merely partial character of either psychological or biological interpretation. We are accustomed to think that since scientific knowledge has cleared up so much that had previously been mysterious, our experience must be much more intelligible to us than it seemed to our forefathers. In so thinking, however, we forget that each scientific advance seems only to throw into clearer relief the mystery which remains. My old philosophical teacher, Professor Campbell Fraser of Edinburgh, used frequently to speak of “our mysterious life in this mysterious universe.” The advance of scientific knowledge does not seem to make either our universe or our life in it any less mysterious. It appears to me to be little better than unthinking credulity to believe that the mystery has become less deep through scientific advance. In proportion as we know more and think more, scientific problems still unsolved seem to define themselves progressively.
Interest and values are not those of mere individual persons, but also social interest and values. The imperfection which is inherent in conscious behaviour from the individual standpoint is still more evidently inherent in the conscious realization of social interest and values. It is only very imperfectly that we either perceive or act upon social interest or values which ought to appeal to us. We are confused and diverted by the mechanical chaos which is everywhere around us, and by what are mere immediate sensuous appeals without continuity behind and in front of them, or by appeals in response to which individual interest is in conflict with common interest. Apart from this, it is only very imperfectly that what we ought to regard as common interest is defined. In nothing is the mystery which surrounds us more evident than in this.
Thus all that we can say of psychological interpretation of experience is that though it is certainly necessary, it only applies in conjunction with what seems to be opposed to it, in the interpretation of which we are only able to employ the more abstract conceptions of biology and physics. Similarly, in the case of biological interpretation, we have seen that it applies in conjunction with what we can only interpret as the mechanical chaos of physical interpretation. We might extend the same line of argument to physical interpretation by pointing out that it is only in virtue of the assumption of purely mathematical relations in ideally empty space and time that physical interpretation becomes possible.
In the present course of lectures it has been argued in much detail that in the interpretation of the visible and tangible world of our experience we cannot dispense with biological interpretation by substituting for it physical interpretation, or employ an interpretation in which interference with physical action is confined to parts of the interior of living organisms. It has also been argued that we cannot dispense with psychological interpretation by substituting for it either physical or biological interpretation: nor can we confine psychologically interpreted interference with physically or biologically interpreted activity to some one part of a living organism, such as the grey matter of the brain.
But granted the validity of these arguments, we have not, as has just been pointed out, got rid of the physical world when we pass to biological interpretation, or of the physical and biological worlds when we pass to psychological interpretation. On the one hand, a merely physical or merely biological interpretation of our experience is impossible; but, on the other hand, we can never dispense with the physical or biological interpretation: for their continued existence seems necessary to the existence of the psychological interpretation. The conclusion which at first sight seems to follow in face of this position is that scientific conceptions represent, not reality itself, but only particular aspects of reality. It is one aspect that is dealt with in the physical sciences, another in the biological sciences, and yet another in the psychological or humanistic sciences. The reality of experience must include them all.
This is a practical conclusion often adopted; but when we examine it, we find that the different aspects or interpretations contradict one another. Reality cannot at the same time be a physico-chemical chaos and a world of biological co-ordination in which each part or distinguishable action expresses the existence of a whole. Nor can reality be at the same time a world the events of which express wholeness only in respect to space-relations and a world in which the wholeness of the events extends over time-relations, so that there is progress and therefore wholeness in history, and values exist which partake of what is eternal or outside of the vicissitudes of time.
If we insist on the reality of the physico-chemical aspect of experience, and at the same time recognize the characteristic features of life and conscious behaviour, we are driven into the position of the vitalists and animists. But the position was found to be as impossible as that of ignoring these characteristic features, and attempting to interpret life and conscious behaviour in physico-chemical terms. If, at the other extreme, we insist on the reality of the psychological or spiritual aspect of experience, we must also recognize the apparent chaos and imperfection which is everywhere around us and thus seems to belong to an alien world. We can, however, never separate this alien world from the psychological or spiritual world, since we cannot separate the activities of the soul from those of the body and its environment.
At the end of the survey of the sciences in the present course of lectures we have thus reached no satisfactory position, though I hope that the survey may have placed in a clear light the difficulties and contradictions to which merely scientific interpretations of our experience lead. These difficulties and contradictions concern all that is of most moment and value to us—all that our affections are centred on, whatever philosophical or religious beliefs we may ostensibly hold. We may be materialists, for whom, theoretically speaking, there is nothing but mechanical chaos in the universe—a chaos of conscious experience, as well as of material happenings, so that such things as spiritual values cannot, properly speaking, exist. In actual fact, however, it is only the value which they accord to truth that leads some men to materialism. Materialists are also usually men of what we call exemplary lives, showing in a striking manner the reality to themselves of spiritual values. We may, at the other extreme, be religious mystics, to whom the chaos of the visible universe is theoretically of no account. In this case, too, the lives of religious mystics belie their opinions. The suffering and sin of the visible world around them concern them deeply, and usually far more deeply than in the case of others who have not clearly realized the need for a philosophy of life.
We require something which goes deeper than any of the sciences—something which faces the contradictions to which the different sciences lead when they are applied to actual experience. We need Philosophy, not merely Science. To the great majority of mankind what we call Religion has stood for their Philosophy. It has at least been a practical philosophy. To what extent we can identify Philosophy and Religion will be discussed in my second course of lectures. At this point I only wish to emphasize the need for Philosophy or Religion, as distinguished from Science, but growing out of it, and consequently the distinction between Philosophy or Religion and Science. I have tried to point out the fundamental differences in the interpretations of our experience by different sciences, and the impossibility of basing a satisfactory philosophy on any particular scientific standpoint, such as that of the physical sciences, or biology, or psychology, or on any combination of scientific standpoints. In concluding this first course of lectures I shall endeavour to summarize the reasons for this conclusion.
Although in Greek times, when not only the great practical value of mathematical reasoning, but the unlimited field of its application, began first to be realized, an attempt was made by the Pythagoreans to base a philosophy on mathematical science, it was soon realized that such an attempt could not express our experience, so that I need not refer to it further. It is very different, however, with physical science; and from Democritus onwards to the most recent times we find attempts to base a philosophy on physical science. As I have tried to point out in detail, these attempts have failed to cover the phenomena of life, and still more completely failed to cover the phenomena of perception and conscious behaviour generally. It seems to me that, in spite of efforts under the name of Realism to revive this physical philosophy, it must be regarded as a definite failure, since it has aimed at the impossible, even when, as in Kant's philosophy, its scope was limited to a merely phenomenal world.
In Lecture VIII I endeavoured to show that a philosophy based on the objective reality of biological conceptions, though it now seems to be in all probability capable of partial extension to the inorganic world, does not account for the phenomena of conscious behaviour. It is also open to the criticism that the conception of life seems to imply the inconsistent conception of mechanical determination, as already pointed out in the present lecture.
We can also endeavour to base a philosophy on the objective reality of psychological or spiritual interpretations of experience and the eternal values which that interpretation reveals—values which do not depend on the existence of mere individual persons, and which are embodied in the development and application of scientific conceptions no less than in other events in human history. But such a philosophy fails, by itself, to account for the chaos and imperfection which, in our actual experience, appear side by side with the world of eternal values. In so far as the chaos and imperfection are real, they contradict the psychological or spiritual interpretation, so that we do not reach a philosophy in this way. Along with the element of what is all-pervasive and eternal in us there is a contradictory element of what is only here and now in a world of chaos.
We fare no better as regards a philosophy if we assume that the spiritual world of values exists side by side with a material world of physico-chemical chaos. All the difficulties and contradictions inherent in animism and vitalism confront us. These difficulties and contradictions have been pointed out in Lectures IV and VI.
The only world which the Sciences appear to be capable of representing to us is not consistent with itself. Not merely mathematical, physical, and biological Science, but Science of any kind, fails to furnish us with what we can describe as objective truth. When we examine the body of knowledge presented to us by each science, we find that though it is logically consistent it only corresponds partially or imperfectly with our actual experience. In other words, it does not represent actual reality, but only a subjective picture of reality. If we take it to represent actual reality, and suppose that the representation constitutes realism, we are only mistaking a form of subjective idealism for realism.
Thus Science brings us to a point at which we require more than Science. In the lectures of next year this subject will be pursued further.