Preserving the spirit of Spencer's teaching we must regard all modes of relatedness which are disclosed by scientific research as part and parcel of the constitution of nature, from whatever Source, knowable or unknowable, that constitution be derived. Of these modes there are many; indeed, if we deal with all concrete cases, their number is legion. For purposes of illustration, however, we may reduce them, rather drastically, to three main types. There are relations of the physico-chemical type,[53] which we may provisionally follow Spencer in regarding as ubiquitous; there are those of the vital type, which are restricted to living organisms; there are those of the cognitive type, which seem to be much more narrowly restricted. How we deal with these is of crucial importance. Denoting them by the letters A, B, C we find that there are progressively ascending modes of relatedness within any given type. There is evolution within each type. Within the physico-chemical type A, for example, atoms, molecules, and synthetic groups of molecules follow in logical order of evolution. Now the successive products, in which this physico-chemical type of relatedness obtains, have certain new and distinctive properties which are not merely the algebraic sum of the properties of the component things prior to synthesis. We may speak of them as constitutive of the products in a higher stage of relatedness, thus distinguishing constitutive from additive properties.[54] Similarly when B, the vital relations, are evolved, the living products, in which these specific relations obtain, have new constitutive properties, on the importance of which vitalists are right in insisting, though I emphatically dissent from some of the conclusions they draw from their presence. For if, beyond the physico-chemical, a special agency be invoked to account for the presence of new constitutive properties, then, in the name of logical consistency, let us invoke special agencies to account for the constitutive properties within the physico-chemical—for radio-active properties for example. If a Source of phenomena be postulated, why not postulate One Source of all phenomena from the very meanest to the very highest? There remains the case of C—the synthetic whole in which cognitive relatedness obtains. This is unquestionably more difficult of scientific interpretation. But I believe that like statements may be made in this case also. What we have, I conceive, is just a new and higher type of relatedness with specific characters of its own. But of this more in the sequel.
It must be remembered that A, B, C stand for relationships and that the related things are progressively more complex within more complex relational wholes. Relationships are every whit as real as are the terms they hold in their grasp. I do not say more real; but I say emphatically as real. And if this be so, then they ought somehow to be introduced into our formulae, instead of being taken for granted. We give H2O as the formula for a molecule of water. But that molecule is something very much more than two atoms of hydrogen + one atom of oxygen. The absolutely distinctive feature of the molecule is the specific relatedness of these atoms. This constitutive mode of relatedness is, however, just taken for granted. And it is scarcely matter for surprise that, when we find not less specific modes of vital relatedness in the living organism, they are too apt to be just ignored!
Revert now to the empirical outcome of scientific research, for as such I regard it, that new constitutive properties emerge when new modes and types of relatedness occur, and when new products are successively formed in evolutional synthesis. This, it will be said, involves the acceptance of what is now commonly called creative evolution. I am far from denying that, in the universe of discourse where Source is under consideration, the adjective is justifiable. But, in the universe of discourse of science, I regard it as inappropriate. What we have is just plain evolution; and we must simply accept the truth—if, as I conceive, it be a truth—that in all true evolution there is more in the conclusion than is given in the premises; which is only a logical way of saying that there is more in the world to-day than there was in the primitive fire-mist. Not more 'matter and energy', but more varied relationships and new properties, quite unpredictable from what one may perhaps speak of as the fire-mist's point of view. This is no new doctrine, though it has received of late a new emphasis. Mill, dealing with causation,[55] speaks of a 'radical and important distinction'. There are, he says in substance, some cases in which the joint effect of the several causes is the algebraical sum of their separate effects. He speaks of this as the 'composition of causes', and illustrates it from the 'composition of forces' in dynamics. 'But in the other description of cases', he says, 'the agencies which are brought together cease entirely, and a totally different set of phenomena arise.' In these cases 'a concurrence of causes takes place which calls into action new laws bearing no analogy to any that we can trace in the separate operation of the causes'. They might, he suggests, be termed 'heteropathic laws'. G. H. Lewes, too,[56] in his Problems of Life and Mind, drew the distinction between properties which are resultant and those which are emergent. These suggestions were open to Spencer's consideration long before the last edition of First Principles appeared. They were, however, too foreign to the established lines of his thought to call for serious consideration.
But if new relationships and new properties appear in the course of evolutionary progress, where is the opportunity for that unification of scientific knowledge which, according to Spencer, is the goal of philosophy? To be frank, I am by no means sure that this question can be answered in a manner that is other than tentative. Perhaps we have not yet reached the stage at which more than provisional unification is possible. Such provisional unification as is suggested by a survey of the facts is that of seemingly uniform correlation in a hierarchy of logical implication. There are certain modes of relatedness which belong to the cognitive type. It would seem that whenever these obtain they may be correlated with other modes of relatedness which are of the vital or physiological type; and that these, in turn, may be correlated with those that are physico-chemical. Thus C implies B, and B implies A. The order cannot be reversed. Physico-chemical relations, as a class, do not imply those that are physiological.[57] The implication is not symmetrical. Spencer was within sight of this when he spoke[58] of the abstract-concrete sciences as 'instrumental' with respect to the concrete sciences, though the latter are not 'instrumental' in the same sense with respect to the former. But unfortunately he regarded the 'chasm' between the two groups as 'absolute'. And for him the proper home of properties—of all properties it would appear—is the abstract-concrete group—mechanics, physics, and chemistry. This seemingly leaves no place for a specific type of properties connected with vital relatedness as such. In fact Spencer's method of treatment reduces all modes of relatedness to the A type, the laws of which are, for him, the primary 'causes' of all kinds of differentiation and integration. Hence the laws of biology and psychology can ultimately be expressed and explained, he thinks, in mechanical or mechanistic terms. But in the doctrine of implication they are just the laws of B and C respectively, though laws of A may underlie them in a logical sense. And as we ascend the evolutionary plane from A to AB and thence to ABC—from the physico-chemical to the vital and thence to the cognitive—we find new modes of relatedness, new forms of more complex integration and synthesis, new properties successively appearing in serial order. This seems to me simply to express, in outline, the net result of interpretation based on empirical observation—though much, very much, requires to be filled in by future research. And the new properties are not merely additive of preceding properties; they are constitutive, and characterize the higher evolutionary products as such. Why they are thus constitutive, science is unable to say. Spencer, of course, calls in the Unknowable to supply the required nexus.[59] Otherwise, in each case, he confesses that 'we can learn nothing more than that here is one of the uniformities in the order of phenomena'.[60] None the less we may be able some day to establish an ordinal correlation[61] of cognitive processes with physiological processes, and an ordinal correlation of these physiological processes with those of the physico-chemical type. That I conceive to be the ideal of strictly scientific interpretation if it is to be raised progressively to a level approaching that of the exact sciences. It certainly is not yet attained. But I see no reason why we should not regard it as attainable. It will involve the very difficult determination of many correlation coefficients and constants—and for some of these our data are, it must be confessed, both scanty and unreliable.
We must here note a much-discussed departure on Spencer's part from his earlier position. On the first page of the Biology in the earlier editions, and in the last, we are told:
'The properties of substances, though destroyed to sense by combination are not destroyed in reality. It follows from the persistence of force that the properties of a compound are resultants of the properties of its components, resultants in which the properties of the components are severally in full action, though mutually obscured.'
There is no hint here of Mill's heteropathic laws nor of Lewes's emergents. But in the last edition a special chapter is inserted on the Dynamic Element in Life. We here find a tardy recognition of the presence of specific vital characters.
'The processes which go on in living things are incomprehensible as the results of any physical actions known to us.... In brief, then, we are obliged to confess that Life in its essence cannot be conceived in physico-chemical terms.'[62]
I speak of this as a tardy recognition; but it is one that does honour to the man; it is a frank admission that his previous treatment was in some measure inadequate, which a smaller man would not have had the honesty or the strength of character to make. Of course it is traced down to the Unknowable. 'Life as a principle of activity is unknown and unknowable; while phenomena are accessible to thought the implied noumenon is inaccessible.'[63] Still, certain specific characteristics of living organisms are explicitly recognized as among the accessible phenomena; and these cannot be conceived in physico-chemical terms. But did Spencer fully realize how big a hole this knocks in the bottom of the purely mechanical interpretation of nature he had for so long championed?