As a continuation of my criticism on Mr. Fiske's views, I think it is desirable to add a few words concerning the speculative annihilation with which he supposes Mr. Spencer's doctrines to have visited Materialism. Of course it is a self-evident truism that the doctrine of Relativity is destructive of Materialism, if by Materialism we mean a theory which ignores that doctrine. In other words, the doctrine of Relativity, if accepted, clearly excludes the doctrine that Matter, _as known phenomenally_, is at all likely to be a true representative of whatever _thing-in-itself_ it may be that constitutes Mind. But this position is fully established by the doctrine of Relativity alone, and is therefore not in the least affected, either by way of confirmation or otherwise, by Mr. Spencer's extended doctrine of the Unknowable--it being only because the latter doctrine presupposes the doctrine of Relativity that it is exclusive of Materialism in the sense which has just been stated. So far, therefore, Mr. Spencer's writings cannot be held to have any special bearing on the doctrine of Materialism. Such a special bearing is only exerted by these writings when they proceed to show that "it seems an imaginable possibility that units of external force may be identical in nature with the units of the force known as feeling." Let us then ascertain how far it is true that the argument already quoted, and which leads to this conclusion, is utterly destructive of Materialism. 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