I must leave to some future Herbert Spencer lecturer the discussion of his doctrine of the Unknowable and the critical consideration of its place and value in philosophy. I would fain leave it altogether on one side; but that is impossible. Although the First Principles is divided into two Parts, dealing respectively with the Unknowable and the Knowable, we have not by any means done with the former when we turn from the First Part to the Second. With Spencer we have never done with the Unknowable, the Unconditioned Reality and the other aliases by which it goes. His persistence of force is the persistence of Unknowable Force. In a leading passage, at any rate, it is avowedly 'the persistence of some Cause which transcends our knowledge and conception. In asserting it we assert an Unconditioned Reality without beginning or end'.[16] There must, he holds, be something at the back of the evolutionary drama which we study—something that is both a principle of activity and a permanent nexus.[17] The pity of it is that we know not, and can never know, what on earth (or in heaven!) it is. We only know that it exists, and somehow produces the whole show. Now it would much conduce to clearness of thought and of statement if we could agree to eliminate those terribly ambiguous words 'force' and 'cause' when we are dealing with the fundamental postulate (if such it be) that there must be something at the back of evolution to make it what it is; and the word Source seems ready to our hand and might well be given this special significance. But Spencer uses Agency, Power, Cause, Force, in this connexion. In how many senses he uses the word 'force' I am not prepared to say. It is often a synonym for cause; it stands alike for matter and energy;[18] it is the objective correlate of our subjective sense of effort.[19] There is a 'correlation and equivalence between external forces and the mental forces generated by them under the form of sensations'.[20] And when we pass to human life in society, whatever in any way facilitates or impedes social, political, or economic change, is spoken of in terms of force.[21] With an apparent vagueness and laxity almost unparalleled, force is used in wellnigh every conceivable sense of this ambiguous word—except, perhaps, that which is now sanctioned by definition in mathematical physics. I say apparent vagueness and laxity because, subtly underlying all this varied usage, is the unifying conception of Source as the ultimate basis of all enforcement. From this flows all necessity whether in things or thoughts or any combination of the two. Thus persistence of force is Spencer's favourite expression for uniform determinism at or near its Source.
Now, as I understand the position, science has nothing whatever to do with the Source or Sources of phenomena. By a wise self-denying ordinance it rules all questions of ultimate origin out of court. It regards them as beyond its special sphere of jurisdiction. It deals with phenomena in terms of connexion within an orderly scheme, and it does not profess to explain why the connexions are such as they are found to be. In any discussion of this or that sequence of events which may fall under the wide and rather vague heading of evolution, it is just a consistent story of the events in their total relatedness that science endeavours to tell. The question: But what evolves the evolved? is for science (or should I say for those who accept this delimitation of the province of science?) not so much unanswerable in any terms, as unanswerable in scientific terms. For the terms in which an answer must be given are incommensurable with the concepts with which science has elected to carry on its business as interpreter of nature. To this question therefore the man of science, speaking for his order, simply replies: We do not know. Is this, then, Spencer's answer? Far from it. The man of science here makes, or should make, no positive assertion, save in respect of the limits of his field of inquiry. If you beg him to tell you what that which he knows not is, or does, he regards such a question as meaningless. But Spencer's Unknowable, notwithstanding its negative prefix, is the Ultimate Reality, and does all that is in any way done. We may not know what it is; but that it is, is the most assured of all assured certainties. And when it comes to doing, what can be more dramatically positive than that which bears a name of negation? Whatever it may not be, it is the Power that drives all the machinery in this workshop of a world; it is the Power which lies at the back of such wit as man has to interpret it, and, in some measure, to utilize its mechanism.
It seems plain enough that Spencer distinguishes, or seeks to distinguish, between those knowable effects which we call natural phenomena and their Unknowable Cause or Source. And this seems to be in line with the distinction which his critic, M. Bergson, draws between 'the evolved which is a result' and 'evolution itself, which is the act by which the result is obtained'.[22] An act implies an agent, and the agency of which the evolved is a manifestation is for M. Bergson Life, while for Spencer it is that very vigorous agency—the Unknowable. Now in criticizing Spencer, M. Bergson says:
'The usual device of the Spencerian method consists in reconstructing evolution with the fragments of the evolved.... It is not however by dividing the evolved that we shall reach the principle of that which evolves. It is not by recomposing the evolved with itself that we shall reproduce the evolution of which it is the term.'[23]
But does Spencer ever suggest that we shall thus reach the principle of that which evolves—by which, if I mistake not, M. Bergson means the Source of evolution? Does he not urge that we can neither reach it in this way, nor in any other way? For M. Bergson, as for Spencer, it is unknowable by the intellect—it can only be known by what M. Bergson calls intuition. For both thinkers, the intellect provides only a world of symbols; and Spencer's transfigured realism may be matched by what Dr. Wildon Carr calls M. Bergson's transformed realism.[24] So long as we are dealing with the evolved—which is that with which alone science attempts to deal—Spencer, M. Bergson, and the rest of us are in like case. We must stumble on intellectually with our symbols as best we may. 'Whether we posit the present structure of mind or the present subdivision of matter in either case we remain in the evolved: we are told nothing of what evolves, nothing of evolution.'[25] Nothing of what evolves! Spencer might exclaim with a groan. Have I then written all those pages and pages on the Unknowable for nought? Is it not a fundamental tenet of my philosophy that there must be, and therefore is, a Source of the evolved—of the phenomenal world which is merely an expression in terms of intellectual symbolism, of that ultimate Power which, though its nature may baffle the intellect, is none the less the most real of all realities?
It would take us too far from the line of Spencer's thought to consider M. Bergson's doctrine that it is the intellect that portions the world into lots;[26] that cuts the facts out of the interpenetrating whole of reality, and renders them artificially distinct within the continuity of becoming. It suffices to note that on such a presupposition 'the cardinal error of Spencer is to take experience already allotted as given, whereas the true problem is to know how the allotment was worked'.[27] I am not prepared to give—indeed I have been unable to find—M. Bergson's own solution of the problem. I gather that it was Life itself that somehow allotted concepts and objects in such correspondence as should be practically useful though metaphysically false and illusory. But just how it was done I have still to learn. 'The original activity was', we are told, 'a simple thing which became diversified through the very construction of mechanisms such as those of the brain,'[28] which, as Life's tool, has facilitated the chopping up of a continuous interpenetrating reality into mince-meat for intellectual assimilation. Such a conception was foreign to Spencer's thought. But some of us may find it hard to distinguish M. Bergson's 'original activity' from Spencer's Unknowable, which, so far as one can make out, somehow produced precisely the same results. As a matter of fact, M. Bergson seems to put into Life, as Spencer put into the Unknowable, the potentiality of producing all that actually exists.
For Spencer, as for M. Bergson, we live in a world of change. But neither is content to accept changes as facts to be linked up within a scheme of scientific interpretation. Both must seek their Source. Now to inquire into the Source or Sources of phenomena is characteristic of man as thinker. And if, in common with those whom I follow, I regard this quest as beyond the limits of science, I am well aware that such delimitation of fields of inquiry is by no means universally accepted. M. Bergson, for example, regards metaphysics as the Science[29] which claims to dispense with symbols, which turns its back on analysis, which eschews logic, which dispenses with relativity and pierces to the absolute, which, apparently, uses the intellect only to establish its utter incompetence in this department of 'science'. Merely saying that this, whatever else it may be, is not what I, for one, understand by science—and not, by the way, what M. Bergson in other passages seems to mean by science[30]—I pass on to Spencer's treatment of the philosophy of science which, for him, is 'completely unified knowledge', 'the truths of philosophy bearing the same relation to the highest scientific truths that each of these bears to lower scientific truths.'
I suppose one of the basal truths in his philosophy of science is for Spencer the universality of connexion between cause and effect. Now let us eliminate Source as the Ultimate Cause (so far as that is possible in Spencer); let us restrict our attention to cause and effect in the realm of the knowable. When we try to do this we find his statements concerning them scarcely less puzzling than those that refer to force, with which cause is so often identified. Thus we are told[31] that 'motion set up in any direction is itself a cause of further motion in that direction since it is a manifestation of a surplus force in that direction'; and elsewhere[32] that 'the momentum of a body causes it to move in a straight line and at a uniform velocity'. A distinction is drawn between cause and conditions. But both produce effects, and only on these terms can there be that 'proportionality or equivalence between cause and effect' on which Spencer insists.[33] There is, however, scarcely a hint of what constitutes the difference between cause and conditions, save in so far as he speaks[34] of 'those conspicuous antecedents which we call the causes' and 'those accompanying antecedents which we call the conditions'. Many of the details of his treatment I find most perplexing; but to recite examples would be wearisome. And then, in the ninth and tenth articles of the Spencerian creed, cause plays a somewhat different part. For, there, the instability of the homogeneous and the multiplication of effects are given as the chief causes which 'necessitate' that redistribution of matter and motion of which evolution is one phase. Similarly, as I have noted above, in 'Progress: its Law and Cause', the fundamental attribute of all modes of change—that every cause produces more than one effect—is itself spoken of as a cause, and likened to 'gravitation as the cause of each of the groups of phenomena which Kepler formulated'. In these cases a generalization is regarded as the cause of the phenomena from which the generalization is drawn. But sometimes it is spoken of as the reason for the phenomena.[35] Here again, however, as throughout his work, reference to Source is close at hand. Hence, in place of the words cause and force, the word agency[36] sometimes stands for that which produces effects; or the word factor may be used. Thus we are told[37] of phenomena continually complicating under the influence of the same original factors'; and we meet with the argument (contra Huxley) that states of consciousness are factors, that is, they 'have the power of working changes in the nervous system and setting up motions'.[38] Always close at hand, constantly underlying Spencer's thought, is the notion of power which works changes. In his treatment of the philosophy of science we are never far from the noumenal Source of phenomena.
'For that interpretation of things which is alone possible for us this is all we require to know—that the force or energy manifested, now in one way now in another, persists or remains unchanged in amount. But when we ask what this energy is, there is no answer save that it is the noumenal Cause implied by the phenomenal effect.'[39]
Was it partly with Spencer in view that Mr. Bertrand Russell recently urged[40] that the word cause 'is so inextricably bound up with misleading associations as to make its complete extrusion from the philosophical vocabulary desirable'? Professor Mach[41] had previously expressed the hope 'that the science of the future will discard the use of cause and effect as formally obscure'. And as long ago as 1870 W. K. Clifford[42] tried to show in 'what sort of way an exact knowledge of the facts would supersede an enquiry after the causes of them'; and urged that the hypothesis of continuity 'involves such an interdependence of the facts of the universe as forbids us to speak of one fact or set of facts as the cause of another fact or set of facts'. Such views may, perhaps, be regarded as extreme; and the word cause is not likely to be extruded from the vocabulary of current speech, of the less exact branches of science, or of general discussions of world-processes. Still, a philosophy of science must take note of this criticism of the use of a term which is, to say the least of it, ambiguous. We must at any rate try to get rid of ambiguity. Now we live in a world of what, in a very broad and inclusive sense, may be called things; and these things are in varied ways related to each other. (I must beg leave to assume, without discussion, that the relatedness of things is no less constitutive of the world with which a philosophy of science has to deal than the things which are in relation.) And when things stand in certain kinds of relatedness to each other changes take place. The trouble is that the kinds of relatedness are so many and the kinds of change are also so many! Spencer tried to reduce all kinds of relatedness to one quasi-mechanical type; and he signally failed—or shall I say that he succeeded only by ignoring all the specific differences on the one hand, and, on the other hand, by so smudgy an extension of the meaning of mechanical and physical terms as to make them do duty in every conceivable connexion?