[170] The compounding of colors may be dealt with in an identical way. Helmholtz has shown that if green light and red light fall simultaneously on the retina, we see the color yellow. The mind-stuff theory would interpret this as a ease where the feeling green and the feeling red 'combine' into the tertium quid of feeling, yellow. What really occurs is no doubt that a third kind of nerve-process is set up when the combined lights impinge on the retina,—not simply the process of red plus the process of green, but something quite different from both or either. Of course, then, there are no feelings, either of red or of green, present to the mind at all; but the feeling of yellow which is there, answers as directly to the nerve-process which momentarily then exists, as the feelings of green and red would answer to their respective nerve-processes did the latter happen to be taking place.
[171] Cf. Mill's Logic, book vi, chap. iv, § 3.
[172] I find in my students an almost invincible tendency to think that we can immediately perceive that feelings do combine. "What!" they say, "is not the taste of lemonade composed of that of lemon plus that of sugar?" This is taking the combining of objects for that of feelings. The physical lemonade contains both the lemon and the sugar, but its taste does not contain their tastes, for if there are any two things which are certainly not present in the taste of lemonade, those are the lemon-sour on the one hand and the sugar-sweet on the other. These tastes are absent utterly. The entirely new taste which is present resembles, it is true, both those tastes; but in [Chapter XIII] we shall see that resemblance can not always be held to involve partial identity.
[173] E. Montgomery, in 'Mind,' v, 18-19. See also [pp. 24-5].
[174] J. Royce, 'Mind,' vi, p. 376. Lotze has set forth the truth of this law more clearly and copiously than any other writer. Unfortunately he is too lengthy to quote. See his Microcosmus, bk. ii, ch. i, § 5; Metaphysik, §§ 242, 260; Outlines of Metaphysics, part ii, chap. i, §§ 3, 4, 5. Compare also Reid's Intellectual Powers, essay v, chap. iii, ad fin.; Bowne's Metaphysics, pp. 361-76; St. J. Mivart: Nature and Thought, pp. 98-101; E. Gurney: 'Monism,' in 'Mind,' vi, 153; and the article by Prof. Royce, just quoted, on 'Mind-stuff and Reality.'
In defence of the mind-stuff view, see W. K. Clifford: 'Mind,' iii, 57 (reprinted in his 'Lectures and Essays,' ii, 71); G. T. Fechner, Psychophysik, Bd. ii, cap. xlv; H. Taine: on Intelligence, bk. iii; E. Haeckel: 'Zellseelen u. Seelenzellen' in Gesammelte pop. Vorträge, Bd. i, p. 143; W. S. Duncan: Conscious Matter, passim; H. Zöllner: Natur d. Cometen, pp. 320 ff.; Alfred Barratt: 'Physical Ethic' and 'Physical Metempiric,' passim; J. Soury: 'Hylozoismus,' in 'Kosmos,' V. Jahrg., Heft x, p. 241; A. Main: 'Mind,' i, 292, 431, 566; ii, 129, 402; Id. Revue Philos., ii, 86, 88, 419; iii, 51, 502; iv, 402; F. W. Frankland: 'Mind,' vi, 116; Whittaker: 'Mind,' vi, 498 (historical); Morton Prince: The Nature of Mind and Human Automatism (1885); A. Riehl: Der philosophische Kriticismus, Bd. ii, Theil 2, 2ter Abschnitt, 2tes Cap. (1887). The clearest of all these Statements is, as far as it goes, that of Prince.
[175] "Someone might say that although it is true that neither a blind man nor a deaf man by himself can compare sounds with colors, yet since one hears and the other sees they might do so both together.... But whether they are apart or close together makes no difference; not even if they permanently keep house together; no, not if they were Siamese twins, or more than Siamese twins, and were inseparably grown together, would it make the assumption any more possible. Only when sound and color are represented in the same reality is it thinkable that they should be compared." (Brentano: Psychologie, p. 209.)
[176] The reader must observe that we are reasoning altogether about the Logic of the mind-stuff theory, about whether it can exist in the constitution of higher mental states by viewing them as identical with lower ones summed together. We say the two sorts of fact are not identical: a higher state is not a lot of lower states; it is itself. When, however, a lot of lower states have come together, or when certain brain-conditions occur together which, if they occurred separately, would produce a lot of lower states, we have not for a moment pretended that a higher state may not emerge. In fact it does emerge under those conditions; and our [Chapter IX] will be mainly devoted to the proof of this fact. But such emergence is that of a new psychic entity, and is toto cœlo different from such an 'integration' of the lower states as the mind-stuff theory affirms.
It may seem strange to suppose that anyone should mistake criticism of a certain theory about a fact for doubt of the fact itself. And yet the confusion is made in high quarters enough to justify our remarks. Mr. J. Ward, in his article Psychology in the Encyclopædia Britannica, speaking of the hypothesis that "a series of feelings can be aware of itself as a series," says (p. 39): "Paradox is too mild a word for it, even contradiction will hardly suffice." Whereupon, Professor Bain takes him thus to task: "As to 'a series of states being aware of itself,' I confess I see no insurmountable difficulty. It may be a fact, or not a fact; it may be a very clumsy expression for what it is applied to; but it is neither paradox nor contradiction. A series merely contradicts an individual, or it may be two or more individuals as coexisting; but that is too general to exclude the possibility of self-knowledge. It certainly does not bring the property of self-knowledge into the foreground, which, however, is not the same as denying it. An algebraic series might know itself, without any contradiction: the only thing against it is the want of evidence of the fact." ('Mind,' xi, 459). Prof. Bain thinks, then, that all the bother is about the difficulty of seeing how a series of feelings can have the knowledge of itself added to it!!! As if anybody ever was troubled about that. That, notoriously enough, is a fact: our consciousness is a series of feelings to which every now and then is added a retrospective consciousness that they have come and gone. What Mr. Ward and I are troubled about is merely the silliness of the mind-stuffists and associationists continuing to say that the 'series of states' is the 'awareness of itself;' that if the states be posited severally, their collective consciousness is eo ipso given; and that we need no farther explanation, or 'evidence of the fact.'
[177] The writers about 'unconscious cerebration' seem sometimes to mean that and sometimes unconscious thought. The arguments which follow are culled from various quarters. The reader will find them most systematically urged by E. von Hartmann: Philosophy of the Unconscious, vol. i; and by E. Colsenet: La Vie Inconsciente de l'Esprit (1880). Consult also T. Laycock: Mind and Brain, vol. i, chap. v (1860); W. B. Carpenter: Mental Physiology, chap. xiii; F. P. Cobbe: Darwinism in Morals and other Essays, essay xi, Unconscious Cerebration (1872); F. Bowen: Modern Philosophy, pp. 428-480; R. H. Hutton: Contemporary Review, vol. xxiv, p. 201; J. S. Mill: Exam. of Hamilton, chap. xv; G. H. Lewes: Problems of Life and Mind, 3d series, Prob. ii, chap. x, and also Prob. iii, chap. ii; D. G. Thompson: A System of Psychology, chap. xxxiii; J. M. Baldwin, Handbook of Psychology, chap. iv.