[150] See what was said on the nature of passive illusions of sense (pp. 44, 68, 70, etc.) The logical character of illusion might be brought out by saying that it resembles the fallacy which is due to reasoning from an approximate generalization as though it were a universal truth. In thus identifying illusion and fallacy, I must not be understood to say that there is, strictly speaking, any such thing as an unconscious reasoning process. On the contrary, I hold that it is a contradiction to talk of any mental operation as altogether unconscious. I simply wish to show that, by a kind of fiction, illusion may be described as the result of a series of steps which, if separately unfolded to consciousness (as they no longer are), would correspond to those of a process of inference. The fact that illusion arises by a process of contraction out of conscious inference seems to justify this use of language, even apart from the fact that the nervous processes in the two cases are pretty certainly the same.
[151] If we turn from the region of physical to that of moral ideas, we see this historical collision between common and individual conviction in a yet more impressive form. The teacher of a new moral truth has again and again been set down to be an illusionist by a society which was itself under the sway of a long-reigning error. As George Eliot observes, "What we call illusions are often, in truth, a wider vision of past and present realities—a willing movement of a man's soul with the larger sweep of the world's forces."
[152] To make this account of the philosophic problem of the object-world complete, I ought to touch not only on the distinction between the vulgar and the scientific view of material things, but also on the distinction, within physical science, between the less and the more abstract view roughly represented by molar and molecular physics.
[153] For an excellent account of the distinction between the scientific and the philosophic point of view, see Mr. Shadworth Hodgson's Philosophy of Reflection, Bk. I. chs. i. and iii.; also Bk. III. chs. vii. and viii.
[154] I hold, in spite of Berkeley's endeavours to reconcile his position with that of common sense, that the popular view does at least tend in this direction. That is to say, the every-day habit, when considering the external world, of abstracting from particular minds, leads on insensibly to that complete detachment of it from mind in general which expresses itself in the first stage of philosophic reflection, crude realism. The physicist appears to me, both from the first essays in Greek "nature-philosophy," as also from the not infrequent confusion even to-day between a perfectly safe "scientific materialism" and a highly questionable philosophic materialism, to share in this tendency to take separate consideration for separate existence. Each new stage of abstraction in physical science gives birth to a new attempt to find an independent reality, a thing-in-itself, hidden further away from sense.
[155] See the interesting autobiographical record of the growth of philosophic doubt in the Première Méditation of Descartes.
[156] The appeal is not, as we have seen, invariably from sight to touch, but may be in the reverse direction, as in the recognition of the duality of the points of a pair of compasses, which seem one to the tactual sense.
[157] I might further remark that this "collective experience" includes previously detected illusions of ourselves and of others.
[158] M. Taine frankly teaches that what is commonly called accurate perception is a "true hallucination" (De l'Intelligence, 2ième partie, Livre I. ch. i. sec. 3).
[159] It only seems to do so, apart from philosophic assumptions, in certain cases where experience testifies to a uniform untrustworthiness of the origin. For example, we may, on grounds of matter of fact and experience, be disposed to distrust any belief that we recognize as springing from an emotional source, from the mind's feelings and wishes.