to propositions no further decomposable”; and (2) this test, like any other, is liable to yield untrue results, “either from incapacity or from carelessness in those who use it”. The force of the second admission depends on the extension given to “incapacity”. Casual and transient incapacity—similar to the occasional logical fallacies that occur in ordinary reasoning—would not seriously impair the value of the criterion; but how if the historical divergences of thought indicate obstinate and widespread incapacity? Mr. Spencer seems to hold that this is not the case if we limit the application of the criterion to simple propositions; thus he contrasts the complexity of the erroneous proposition maintained by those who regarded the existence of antipodes as inconceivable with the simplicity of the propositions that “embody the ultimate relations of space”. But the proposition that “heavy things must fall downward” is apparently as simple as the proposition that “two straight lines cannot enclose a space”; and if analysis reveals complexity in the notions connected in the former proposition, this is equally the case with the latter, according to Spencer’s own account of spatial perception: since, in his view, any perception of space involves “an aggregate of simultaneous states of consciousness symbolising a series of states to which it is found equivalent”.
The difficulty of applying this criterion is forcibly presented when we examine the philosophical doctrine to support which it is especially propounded. For Mr. Spencer’s primary aim in establishing it is to defend Realism against Idealism: this he regards as vital to his system, since “if Idealism is true, the doctrine of Evolution is a dream”. Now, he nowhere, I think, expressly defines Realism: but his argument throughout implies that what is defended is the proposition that the Non-ego exists independently of the Ego. It is this proposition of which he seems to hold the negation inconceivable in any particular case of external perception: as (e.g.) where he speaks (Princ. of Psych., § 441) of the “primary deliverances of consciousness which yield subject and object as independent existences;” and it is in this sense, as I understand, that in his First Principles (§§ 44, 45) he speaks of the “division of self from not-self” as “the primordial datum of Philosophy”. If now we ask what “self” and “not-self” exactly mean, it is explained that we apply the term Self, Ego to an aggregate or series of faint states of consciousness, and the terms Not-self, Non-ego to an aggregate or series of vivid states: “or rather more truly—each order of manifestations carries with it the irresistible
