In the first place, I may observe that this argument differs in several instructive particulars from the anti-materialistic argument of Locke, which we have already had occasion to consider. For while Locke erroneously imagined that the test of inconceivability is of equivalent value wherever it is applied, save only where it conflicts with preconceived ideas on the subject of Theism (see [Appendix A.]), Spencer, of course, is much too careful a thinker to fall into so obvious a fallacy. But again, it is curious to observe that in the anti-materialistic argument of Spencer the test of inconceivability is used in a manner the precise opposite of that in which it is used in the anti-materialistic argument of Locke. For while the ground of Locke's argument is that Materialism must be untrue because it is inconceivable that Matter (and Force) should be of a psychical nature; the ground of Spencer's argument is that what we know as Force (and Matter) may not inconceivably be of a psychical nature. For my own part, I think that Spencer's argument is, psychologically speaking, the more valid of the two; but nevertheless I think that, logically speaking, it is likewise invalid to a perceptibly great, and to a further indefinite, degree. For the argument sets out with the reflection that we can only know Matter and Force as symbols of consciousness, while we know consciousness directly, and therefore that we can go further in conceivably translating Matter and Force into terms of Mind than vice versa. And this is true, but it does not therefore follow that the truth is more likely to lie in the direction that thought can most easily travel. For although I am at one with Mr. Spencer, whom Mr. Fiske follows, in regarding his test of truth—viz., inconceivability of a negation—as the most ultimate test within our reach, I cannot agree with him that in this particular case it is the most trustworthy test within our reach. I cannot do so because the reflection is forced upon me that, "as the terms which are contemplated in this particular case are respectively the highest abstractions of objective and of subjective existence, the test of truth in question is neutralised by directly encountering the inconceivable relation that exists between subject and object." Or, in other words, as before stated, "whatever the cause of Mind may be, we can clearly perceive it to be a subjective necessity of the case that, in ultimate analysis, we should find it more easy to conceive of this cause as resembling Mind—the only entity of which we are directly conscious—than to conceive of it as any other entity of which we are only indirectly conscious." When, therefore, Mr. Spencer argues that "it is impossible to interpret inner existence in terms of outer existence," while it is not so impossible to interpret outer existence in terms of inner existence, the fact is merely what we should in any case expect à priori to be the fact, and therefore as a fact it is not a very surprising discovery à posteriori. So that when Mr. Fiske proceeds to make this fact the basis of his argument, that because we can more conceivably regard objective existence as like in kind to subjective existence than conversely, therefore we should conclude that there is a corresponding probability in favour of the more conceivable proposition, I demur to his argument. For, fully accepting the fact on which the argument rests, and it seems to me, in view of what I have said, that the latter assigns an altogether disproportionate value to the test of inconceivability in this case. Far from endowing this test with so great an authority in this case, I should regard it not only as perceptibly of very small validity, but, as I have said, invalid to a degree which we have no means of ascertaining. If it be asked, What other gauge of probability can we have in this matter other than such a direct appeal to consciousness? I answer, that this appeal being here à priori invalid, we are left to fall back upon the formal probability which is established by an application of scientific canons to objective phenomena. (See footnote in [§ 14].) For, be it carefully observed, Mr. Spencer, and his disciple Mr. Fiske, are not idealists. Were this the case, of course the test of an immediate appeal to consciousness would be to them the only test available. But, on the contrary, as all the world knows, Mr. Spencer asserts the existence of an unknown Reality, of which all phenomena are the manifestations. Consequently, what we call Force and Matter are, according to this doctrine, phenomenal manifestations of this objective Reality. That is to say, for aught that we can know, Force and Matter may be anything within the whole range of the possible; and the only limitation that can be assigned to them is, that they are modes of existence which are independent of, or objective to, our individual consciousness, but which are uniformly translated into consciousness as Force and Matter. Now it does not signify one iota for the purposes of Materialism whether these our symbolical representations of Force and Matter are accurate or inaccurate representations of their corresponding realities,—unless, of course, some independent reason could be shown for supposing that in their reality they resemble Mind. Call Force x and Matter y, and so long as we are agreed that x and y are objective realities which are uniformly translated into consciousness as Force and Matter, the materialistic deductions remain unaffected by this mere change in our terminology; these essential facts are allowed to remain substantially as before, namely, that there is an external something or external somethings—Matter and Force, or x and y—which themselves display no observable tokens of consciousness, but which are invariably associated with consciousness in a highly distinctive manner.
I dwell at length upon this subject, because although Mr. Spencer himself does not appear to attach much weight to his argument, Mr. Fiske, as we have seen, elevates it into a basis for "Cosmic Theism." Yet so far is this argument from "ruling out," as Mr. Fiske asserts, the essential doctrine of Materialism—i.e., the doctrine that what we know as Mind is an effect of certain collocations and distributions of what we know as Matter and Force—that the argument might be employed with almost the same degree of effect, or absence of effect, to disprove any instance of recognised causation. Thus, for example, the doctrine of Materialism is no more "ruled out" by the reflection that what we cognise as cerebral matter is only cognised relatively, than would the doctrine of chemical equivalents be "ruled out" by the parallel reflection that what we cognise as chemical elements are only cognised relatively. I say advisedly, "with almost the same degree of effect," because, to be strictly accurate, we ought not altogether to ignore the indefinitely slender presumption which Mr. Spencer's subjective test of inconceivability establishes on the side of Spiritualism, as against the objective evidence of causation on the side of Materialism. As this is an important subject, I will be a little more explicit. We are agreed that Force and Matter are entities external to consciousness, of which we can possess only symbolical knowledge. Therefore, as we have said, Force and Matter may be anything within the whole range of the possible. But we know that Mind is a possible entity, while we have no certain knowledge of any other possible entity. Hence we are justified in saying, It is possible that Force and Matter may be identical with the only entity which we know as certainly possible; but forasmuch as we do not know the sum of possible entities, we have no means of calculating the chances there are that what we know as Force and Matter are identical in nature with Mind. Still, that there is a chance we cannot dispute; all we can assert is, that we are unable to determine its value, and that it would be a mistake to suppose we can do so, even in the lowest degree, by Mr. Spencer's test of inconceivability. Nevertheless, the fact that there is such a chance renders it in some indeterminate degree more probable that what we know as Force and Matter are identical with what we know as Mind, than that what we know as oxygen and hydrogen are identical with what we know as water. So that to this extent the essential doctrine of Materialism is "ruled out" in a further degree by the philosophy of the Unknowable than is the chemical doctrine of equivalents. But, of course, this indefinite possibility of what we know as Force and Matter being identical with what we know as Mind does not neutralise, in any determinable degree, the considerations whereby Materialism in its present shape infers that what we know as Force and Matter are probably distinct from what we know as Mind.
But I see no reason why Materialism should be restricted to this "its present shape." Even if we admit to the fullest extent the validity of Mr. Spencer's argument, and conclude with Professor Clifford as a matter of probability that "the universe consists entirely of Mind-stuff," I do not see that the admission would affect Materialism in any essential respect. For here again the admission would amount to little else, so far as Materialism is directly concerned, than a change of terminology: instead of calling objective existence "Matter," we call it "Mind-stuff." I say "to little else," because no doubt in one particular there is here some change introduced in the speculative standing of the subject. So long as Matter and Mind, x and y, are held to be antithetically opposed in substance, so long must Materialism suppose that a connection of causality subsists between the two, such that the former substance is produced in some unaccountable way by the latter. But when Matter and Mind, x and y, are supposed to be identical in substance, the need for any additional supposition as to a causal connection is excluded. But unless we hold, what seems to me an uncalled-for opinion, that the essential feature of Materialism consists in a postulation of a causal connection between x and y, it would appear that the only effect of supposing x and y to be really but one substance z, must be that of strengthening the essential doctrine of Materialism—the doctrine, namely, that conscious intellectual existence is necessarily associated with that form of existence which we know phenomenally as Matter and Motion. If it is true that a "a moving molecule of inorganic matter does not possess mind or consciousness, but it possesses a small piece of Mind-stuff," then assuredly the central position of Materialism is shown to be impregnable. For while it remains as true as ever that mind and consciousness can only emerge when what we know phenomenally as "Matter takes the complex form of a living brain," we have abolished the necessity for assuming even a causal connection between the substance of what we know phenomenally as Matter and the substance of what we know phenomenally as Mind: we have found that, in the last resort, the phenomenal connection between what we know as Matter and what we know as Mind is actually even more intimate than a connection of causality; we have found that it is a substantial identity.
To sum up this discussion. We have considered the bearing of modern speculation on the doctrine of Materialism in three successive stages of argument. First, we had to consider the bearing on Materialism of the simple doctrine of Relativity. Here we saw that Materialism was only affected to the extent of being compelled to allow that what we know as Matter and Motion are not known as they are in themselves. But we also saw that, as the inscrutable realities are uniformly translated into consciousness as Matter and Motion, it still remains as true as ever that what we know as Matter and Motion may be the causes of what we know as Mind. Even, therefore, if the supposition of causality is taken to be an essential feature of Materialism, Materialism would be in no wise affected by substituting for the words Matter and Motion the symbols x and y.
The second of the three stages consisted in showing that Mr. Spencer's argument as to the possible identity of Force and Feeling is not in itself sufficient to overthrow the doctrine that what we know as Matter and Motion may be the cause of what we know as Mind. For the mere fact of its being more conceivable that units of Force should resemble units of Feeling than conversely, is no warrant for concluding that in reality any corresponding probability obtains. The test of conceivability, although the most ultimate test that is available, is here rendered vague and valueless by the à priori consideration that whatever the cause of Mind may be (if it has a cause), we must find it more easy to conceive of this cause as resembling Mind than to conceive of it as resembling any other entity of which we are only conscious indirectly.
Lastly, in the third place, we saw that even if Mr. Spencer's argument were fully subscribed to, and Mind in its substantial essence were conceded to be causeless, the central position of Materialism would still remain unaffected. For Mr. Spencer does not suppose that his "units of Force" are themselves endowed with consciousness, any more than Professor Clifford supposes his "moving molecules of inorganic matter" to be thus endowed. So that the only change which these possibilities, even if conceded to be actualities, produce in the speculative standing of Materialism, is to show that the raw material of consciousness, instead of requiring to be caused by other substances—Matter and Force, x and y,—occurs ready made as those substances. But the essential feature of Materialism remains untouched—namely, that what we know as Mind is dependent (whether by way of causality or not is immaterial) on highly complex forms of what we know as Matter, in association with highly peculiar distributions of what we know as Force.