Psychological Idealism is best known to most readers through Mr. J. S. Mill. The Theological view, so far as this country goes, seems to have made scant progress beyond Berkeley and a few of his clever followers. For ordinary Englishmen, a reference to continental writers on this question seems useless;—Theology being discussed by them in so ab extrâ a manner as to put them out of court with even the most metaphysical of our theologians.
Regarding the subject in a psychological light, Mr. O'Hanlon made the following common-sense remarks amongst others of a more abstract nature:[127]—
"To come now to Mr. Mill's Idealism. He, as all the world of thinkers knows, following the steps of Berkeley and Hume, claims, by means of his power of analysis, and by the aid of the formidable psychological instrument furnished him by the doctrine of the Association of Ideas, to have got rid of all other existences save and except states of consciousness, actual and possible.... I propose to try and answer his arguments" (i.e. within certain expressed limitations)—
"Let A = all my sensations.
" B = the group of sensations and of permanent possibilities of sensation I call my body.
" C = the group of permanent possibilities of sensation I call my friend Smith.
"Now I find B always related to A in a very peculiar manner. B has in perpetual conjunction with it a long series of manifold states of consciousness, A. C resembles B in very many particulars, but it is not so related to A. I hence conclude, if I follow Mr. Mill, that C is so related to some other A, that is, to some other consciousness. In drawing this conclusion, in extending to C, which so closely resembles B, my experience of B, I, according to Mr. Mill, do but extend the principles of inductive evidence, which experience shews hold good of my states of consciousness, to a sphere without my consciousness."
The italicized words sound simple enough to the ordinary reader, but argument upon them involves (as Mr. O'Hanlon observes) two serious postulates. "(a) That there is a sphere beyond my consciousness; the very thing to be proved, (b) That the laws, which obtain in my consciousness, also obtain in the sphere beyond it." But;—
"'Such an inference'" he goes on to quote from Mill "'would only be warrantable if we could know à priori that we must have been created capable of conceiving whatever is capable of existing: that the universe of thought and that of reality, the microcosm and the macrocosm (as they once were called) must have been framed in complete correspondence with one another. That this is really the case has been laid down expressly by some systems of philosophy, by implication in more, and is the foundation (among others) of the systems of Schelling and Hegel; but an assumption more destitute of evidence could scarcely be made, nor can one easily imagine any evidence that could prove it unless it were revealed from above.'" Mill on Hamilton, chap. VI. p. 65.
The reader will probably see at once where the abstract difficulty lies, and how it runs up into the higher metaphysics.
Now, as Mr. O'Hanlon puts the case, taking all this for granted;
"A boy cuts his finger and screams.... Yet if I was not by, the boy, the knife, the blood, the scream, would only exist potentially."