[155] See the interesting autobiographical record of the growth of philosophic doubt in the Premiere Meditation 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, 2ieme 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.

I may add that a so-called intuitive belief may refer to a matter of fact which can be tested by the facts of experience and by scientific methods.  Thus, for example, the old and now exploded form of the doctrine of innate ideas, which declared that children were born with certain ideas ready made, might be tested by observation of childhood, and reasoning from its general intellectual condition.  The same applies to the physiological theories of space-perception, supposed to be based on Kant’s doctrine, put forward in Germany by Johannes Mueller and the “nativistic school.” (See my exposition and criticism of these doctrines in Mind, April, 1878, pp. 168-178 and 193-195.)