As this second series of Gifford Lectures is continuous with the first series, I must first remind you of the ground covered last year.
I began the lectures by pointing out that the function of Philosophy is to enable us to frame as consistent as possible a working conception, not merely of part, but of the whole of our experience; and in the lectures of last year I surveyed the interpretations of experience embodied in different main branches of knowledge, or sciences, represented by the physical sciences, the biological sciences, and the psychological or humanistic sciences. I endeavoured to point out the fundamental differences in the general mode of interpretation forced upon us in each of these main branches of science by the nature of our experience itself, and the complete failure of the attempts which have been made to explain away or ignore these differences.
The first five lectures were taken up with the fundamental distinction between biological and purely physical interpretation. The general lines of a purely physical or mechanical interpretation of visible and tangible experience were formulated generally by Newton, and have been developed more and more completely since his time; but biology had no Newton, and it is only by slow degrees, and in face of many misconceptions, that the principles of biological interpretation have been emerging in clear form. Hence a full discussion of the subject was required. I considered at some length the attempts which have been made to treat biology as a part of physics and chemistry, and pointed out the failure of these attempts. I also pointed out the failure of the attempts by the vitalistic school of biologists to interpret biological facts by assuming the existence of spatial demarcation between what is alive and what belongs to a merely physical world, and then endeavouring to study the specific phenomena of life as manifested within the assumed spatial bounds.
The conclusion reached was that there are no spatial boundaries between the living and non-living, and that biology represents an independent group of sciences because the general conception applied, and necessarily applied, in the biological sciences is different from that applied in the physical sciences. The difference consists in the fact that we do not, as in physical interpretation, regard an organism and its environment as consisting of things existing independently of one another in space, but must regard them as forming a co-ordinated whole, of which the observed form, composition, and activity are at all times the expression. In so far as we perceive this co-ordinated whole we are interpreting our observations biologically. In so far as we are unable to do so, we have recourse to mere physical interpretation to the extent which is possible, though this interpretation is evidently of only a provisional character. The old question as to the relation of matter to life is thus in reality a question as to the relation to one another of two different interpretations of the same phenomena, each of which interpretations is in practice not only useful, but even indispensable. It is no individual caprice that necessitates these very different modes of interpretation, but the nature of our experience itself.
In the succeeding lectures I pointed out the further distinction between biologically and psychologically interpreted phenomena. In psychological knowledge something enters into our interpretation, and definitely distinguishes psychological from mere biological interpretation. This additional character is the fact that in psychological interpretation we assume, and must assume, the existence of unity embracing not only the spatial relations of what we are perceiving, but also relations of time, so that the present is the fulfilment of the past and the promise of the future. When we interpret our experience psychologically, each experience is an expression of unity of the past and future with the present. When we are conscious of anything, or when we act voluntarily, retrospect and foresight are of the essence of our experience: present, past, and future are united in the interest or value which the conscious experience or act embodies. We are moving in a psychological or spiritual world of interest and values which are not only embodied in each perception or act, but have no beginning or ending in either space or time.
Psychology which does not take this characteristic into account is nothing but pseudo-psychology. It may be, and sometimes is, good physiology, or sometimes good physics, in so far as physical or biological interpretation can be applied; but it is not psychology. In so far as it is mere physical interpretation it simply ignores all that is characteristic, not only of psychological, but also of biological phenomena. In so far as it is no more than physiological or biological interpretation, it misses what is distinctively characteristic of psychological phenomena. For biological interpretation life is continuous in time. From generation to generation there is no break in the continuity of life, just as, for ordinary physical interpretation, there is no break in the continuity of mass and energy. But in biological, just as in physical interpretation, the detailed happenings of the present are not regarded as having any direct connexion with the detailed happenings of the past or future. Blind immediacy of response to whatever happens is characteristic of phenomena which are interpreted biologically, though the responses themselves, when taken together, express the maintenance of a spatially coordinated whole. On the other hand, retrospect and foresight are embodied in each psychologically interpreted phenomenon, and are of its essence, in addition to mere spatial co-ordination. It is only when we mistakenly apply physical conceptions to psychological phenomena that any question arises as to the relation of body to soul. No such question can arise legitimately, since space and time are not outside psychological unity, but within it. Both animism and materialism are based on the mistake of failing to realize this fact.
The last lecture of the series was devoted to calling attention to the essential defects in scientific interpretation, whether the interpretation be physical, biological, or psychological. The defects in physical interpretation arise from the incompleteness with which what we actually perceive can be interpreted physically, and are evident at once when we endeavour seriously to apply physical conceptions to biological or psychological phenomena. The physical conceptions do not correspond with biological observation, as was pointed out in some detail in the second and third lectures. The want of correspondence has, in the past, been obscured by the fact that during the two centuries since Newton's time physicists had with few exceptions deliberately excluded biological and psychological phenomena from their consideration, accepting, as they usually did, the vitalistic or animistic accounts of these phenomena. It has thus been left mainly to biologists to point out the impossibility alike of vitalistic accounts and of physical accounts of life. In recent years, however, inherent defects of physical interpretation have come to the surface apart altogether from what are ordinarily regarded as biological or psychological phenomena. Recent modifications in the conception of motion or of the atom, for instance, are inconsistent with physical principles on the lines laid down by Newton; and the behaviour of substances with varying temperature furnishes another instance.
On the other hand, if we attempt to apply biological conception consistently to the world of our experience we are at once brought up by the impossibility of realizing in detail any such attempt. Biological interpretation is based on the observation of unified co-ordination in the details of form, composition, and activity; but quite evidently this co-ordination cannot be traced in full detail. The nearer we approach to a centre of living activity the more clearly does it appear to us that the molecules, atoms, and electrons present on the physical interpretation are behaving as if they were taking part in a co-ordinated dance, for which there can be no physical interpretation, and which differs entirely from the free chaotic movements of the apparent molecules in a gas, the mutually confined movements in a liquid, or the still more confined movements in a solid. It is none the less true, however, that side by side with the co-ordination there appears to be everywhere the chaotic activity exhibited in the gaseous, liquid, and solid states as interpreted physically.
In so far as it exists, the co-ordination appears to us as if it were in some mysterious way partially and by brute force imposed on the chaos. In other words, it is only partially and imperfectly that the biological conceptions can be applied to our experience; and as we pass outwards from a centre of life to its spatial environment, the applicability seems to become less and less evident in matters of detail. We seem to be surrounded by mere gases, liquids, and solids, and it is only in the quite general mutual relations between organism and environment that biological co-ordination stands out. Life thus appears to us, from the physical standpoint, as a continuous struggle against physical chaos.
Perhaps some of my audience do not clearly realize what is implied in the physical conception of a gas, liquid, or solid, and in the conception of its temperature. The Collected Scientific Papers are now on the point of appearing of J. J. Waterston, the great Scottish physicist, who was the first to formulate clearly the dynamical theory of gases and of temperature, and afterwards took essential steps in extending the theory to liquids and solids, though he never, in his lifetime, received the recognition due to him. My own book Gases and Liquids, in which I have endeavoured to extend the application of similar reasoning, is also just appearing.1 It was Waterston who first showed how to extend to the molecular world the general principles formulated by Newton, and whose ideas, to a large extent re-discovered and developed by others, form the foundation of molecular physics or physical chemistry as a wonderfully useful branch of physical and chemical science.
The essential points in the physical conception of a gas are as follows. A perfect gas can be regarded successfully as an absolutely disorderly and chaotic assemblage of perfectly elastic molecules flying about with enormous velocity and striking one another and the walls of any containing vessel at all possible angles and with most variable velocities. The pressure of the gas is due to the bombardment by the molecules, and, if we neglect the volume, almost inappreciable at ordinary pressures and temperatures, of the molecules themselves, necessarily varies with their concentration in accordance with the law discovered empirically by Boyle. The pressure must also vary with the mean energy of impact of the molecules, or as the mean square of the molecular velocity. This corresponds to the temperature of the gas, so that we have a clear conception of what temperature means, and can extend it to liquids and solids. We can then see that if the walls of the confining vessel have the same temperature as the gas, the gas-molecules cannot lose any of their energy. If we regard the absolute temperature of a gas as varying with the mean square of the molecular velocity, we can also at once deduce Charles's empirical law of expansion of gases with temperature. Since, moreover, in a chaotic assemblage of countless molecules the energy will, on an average, be equally distributed among the molecules, whether they are relatively heavy or light, equal volumes of gas at the same pressure and temperature will contain the same number of molecules, in accordance with the empirically discovered generalization known as Avogadro's law. The rate of diffusion of a gas will also vary as the square root of its molecular weight, in accordance with Graham's empirically discovered law.
The behaviour of a gas is thus chaotic behaviour, and its temperature is simply a measure of the chaotic kinetic energy which it possesses. Gases, liquids, and solids are present within and around living organisms. They also have temperatures, so that chaotic energy is everywhere present within them; and however evident may be the co-ordination which shows itself in organic behaviour, the chaos seems also to remain side by side with it, so that a consistent account of the phenomena is impossible.
When we pass from biological to psychological interpretation, the incompleteness of psychological interpretation is even more evident than that of biological interpretation. Although in psychological interpretation we make the most of the unity and co-ordination, both in time-relations and space-relations, which we find in our experience, we seem also to be mere individuals, existing among, and struggling with, other individuals in a more or less chaotic environment, and only here and now. But for this appearance space- and time-relations would be only the manner in which psychological unity expresses itself. As spiritually existing we should not exist as individuals in space and time at all, but space- and time-relations would be an expression of our own nature. Past and future would be an everlasting present, and arrangement in space would be an omnipresent here. Our actual experience, however, seems everywhere to be in conflict with psychological or spiritual unity, though it is equally true that this unity is involved in actual experience. From the psychological standpoint it is a world full of sin and sorrow that seems to present itself: for its defects are our defects.
It is thus evident that not only the sciences taken together, but also the individual sciences, present to us problems which, as mere sciences, they are unable to solve. The task of philosophy is to grasp these problems firmly, and endeavour to reach some sort of solution of them. This is what philosophy has always been striving to do, and what, on the practical side, religions have likewise been striving after.
In the first course of my Gifford Lectures I made a survey and comparison of the sciences. The second course will be devoted to philosophical discussion of the problems which, when considered together, they present, and to the practical bearings of the discussion. In the rest of this opening lecture of the second course I shall endeavour to indicate the general lines of the discussion and its outcome, to serve as a sort of guide to the second course.
If we compare the biological with the physical interpretation of experience we find that life, though it appears to us as a struggle against physico-chemical mechanism, is something inherent in the apparent mechanism itself. Any other conclusion involves us in the impossible assumption that life is mere physico-chemical mechanism, or the equally impossible vitalistic interpretation. Despite appearances, therefore, the mechanism must be more than mechanism. The apparent independence of one another of different units of matter and energy can thus be no more than a superficial appearance. In other words, physical science deals with reality in only its superficial appearances, however satisfactory may be such a treatment of reality so long as we leave out of consideration the phenomena of life and any other phenomena which are inconsistent with mechanical conceptions.
For endless immediately practical purposes we can treat the visible and tangible world as a mechanical world; but it is not with these immediately practical purposes that we are at present concerned. We may say that in inorganic phenomena we find the “promise and potency” of all life. But in so saying we are either in fact attributing to inorganic phenomena something quite different from mechanical characters, or we are ignoring the essential character of life, as this essential character was ignored by the majority of physiologists during the last half of the nineteenth century, and is still quite commonly ignored in at any rate a great deal of popular literature.
When we study the life of any higher organism we can distinguish in it with the microscope what seem to be innumerable centres of life, in the form of cells, parts of cells, or of the nuclei of cells; and we find that in the process of hereditary transmission the last-mentioned centres take part in various ways. Yet it is one life that manifests itself in these distinguishable activities. If we go beyond the microscopically visible centres of life to molecules and atoms concerned in life we cannot assume that their nature is in ultimate analysis mechanical. We can, it is true, interpret their behaviour mechanically in what we call a gas or liquid; but unless we are prepared to return to the impossible vitalistic position, we must assume that they too are not in reality mere separable units but would, if we understood them fully, manifest in their behaviour the same organic unity as the microscopically distinguishable centres taken together. In other words, biology cannot accept as more than merely provisional the mechanical interpretation of these ultramicroscopic centres, although in describing the phenomena of life we cannot help making use of physico-chemical description in matters of detail.
When we look, not inwards to what is very small, but outwards to the general environment, and to the mutual relationship of different apparent units of life which may seem at first sight to be merely mechanically affecting one another, biology again cannot accept this appearance as representing reality. Just as the individual cells in a higher organism manifest in their actual behaviour organic unity, so do these higher organisms themselves present evidences of organic unity in their relations to one another. We can see this in the relations between the sexes, between parent and offspring, and between the members of communities of organisms; and biology deals with this unity, and generally with the unity of organism and its environment, whether that environment includes within itself other living organisms or not. The environment is not treated as something foreign to life. There is no limit to either external or internal biological interpretation. For biology the mechanical interpretation of the environment, including the relations between different organisms, is only a provisional practical interpretation, covering what cannot as yet be interpreted biologically. Underlying this provisional interpretation, however, is the postulate that biological interpretation must be ultimately possible.
This involves what may be called an act of scientific faith, but of faith very firmly based on experience. In and about the living body we seem, from the physical standpoint, to find innumerable independent bodies mutually acting on one another. Yet the outcome is the active maintenance of specific and co-ordinated structure. It is this fundamental fact which justifies the act of faith by which we assume an underlying biological interpretation. Those sceptics who object on principle to any such act of faith may be reminded that it is by a precisely similar act of faith that they interpret the behaviour of a gas, or the nature of heat or temperature, or indeed make use at all of the generalized conceptions of mass and energy. Without these latter conceptions we are unable to describe or think definitely about what we regard as a physical world; and without the distinctively biological conception of life we are unable to describe and think definitely about the same world when we take the biological phenomena in it into consideration.
Since the time of Newton and his immediate predecessors the civilized world has become accustomed to treat the visible and tangible world altogether independently of the facts with which biology deals. There is, however, as little justification for this treatment as there would be for ignoring all the facts which we relate to the behaviour of molecules and atoms; and when biological facts are taken into consideration, the Newtonian conception of self-existent bodies and their independent motion is no longer possible except as a merely provisional conception.
The visible and tangible world is, however, not only a world of life, but also of conscious behaviour; and in forming a consistent or philosophical conception of our universe we can no more neglect conscious behaviour than we can neglect biological phenomena. When we neglect conscious behaviour we only reach, by an act of faith, towards a biological conception of our universe. When we take conscious behaviour into consideration we must take another step forwards, and by a similar act of faith, towards a psychological or spiritual interpretation.
As was shown in detail in the first course of lectures, a merely biological interpretation of conscious behaviour is quite insufficient. Yet the phenomena of conscious behaviour enter into our visible and tangible experience —into the phenomena of Nature, when “Nature” is taken in its widest sense as synonymous with Experience. Any consistent or philosophical account of Nature must therefore cover conscious experience. Since we cannot interpret conscious experience in terms of mere life, and far less in terms of physical conceptions, there is no escape from the conclusion that behind the appearances of a physical or biological world we are in presence of a psychological or spiritual world. We cannot, however, see this spiritual world in detail, and have to content ourselves for endless ordinary practical purposes with provisional physical or biological interpretations. It is thus only by an act of faith that all the variegated experiences which appear to us as “Nature” are interpreted as in ultimate analysis spiritual.
Neither space-relations nor time-relations are outside this spiritual interpretation. Just as space-relations express the organic unity of life, so time-relations express in addition the progressive unity of spiritual existence, and time-relations have no reality apart from the space-relations in which interest and values are also expressed. We cannot get outside spiritual unity by going backwards or forwards in time. And just as organic unity pervades the individual cells or other units of a living organism, or different organisms, so does spiritual unity pervade individual personalities, so that our universe appears to us as an objective universe, common to all. In ultimate analysis there can be only one spiritual unity or personality.
It is only in what appears to us as an active struggle against mechanical chaos that life manifests itself; and similarly it is only in active struggle against apparent physical or biological chaos that spiritual unity manifests itself. But from the standpoint reached by faith in an all-embracing spiritual unity the chaos disappears as such, since the apparent vicissitudes of existence in time are no longer outside of the spiritual unity, but must themselves be manifestations of it. The apparent evil and imperfection of the universe are no longer interpreted as evil, but only as imperfect apprehension.
Apprehension is always imperfect, since knowledge or scientific perception of any sort is imperfect. It is only by faith that we can realize spiritual reality. In so far as we regard ourselves as mere individuals we are subject to all the vicissitudes of spatial and temporal existence. We are born and die, like other individuals, though the life that was in us is carried on by other generations. But in our conscious behaviour we partake also of spiritual existence which neither dies nor is born, since time-relations are within and not outside it.
It is only by faith, and certainly not by direct perception, that we realize all-embracing spiritual reality; and we can ultimately define faith as the conviction that our universe is consistent with itself. From the standpoint of philosophy which surveys not merely one aspect, but all aspects, of our experience, no consistency is possible unless spiritual reality is one and all-inclusive.
Spiritual reality leaves neither time nor space outside of it. They are only the order in which it expresses itself. Nor can there be separate spiritual realities. Interest and values are thus no mere individual interest and values, nor are our lives mere individual spiritual lives. Only in so far as we mistakenly regard ourselves and our interests as mere individual selves and individual interests is death an ending.
It is only fitfully and in a more or less confused manner that we realize and act upon what is implied in spiritual unity. In the philosophies and religions of history we find, however, that this all-inclusive unity is represented under one form or another, and very clearly in the Christianity under the influence of which we live. The conclusion to which the argument of this course of lectures will lead up is that our universe, under whatever guise of constituent self-existent things or personalities it may for the moment appear to us, can be nothing else but the manifestation of one Spiritual Reality or one God.
It is thus what may be called spiritual realism that this course of lectures will represent.
Gases and Liquids: a Contribution to Molecular Physics. By J. S. Haldane, Oliver & Boyd, 1928.