ABSTRACT
David Hume should therefore have substituted the distinction between definable and indefinable terms for that between complex and simple ideas. His problem of the missing shade of blue, the man is supposed to know the missing shade by description, as the shade intermediate between two shades with which he is acquainted. The evidence for the doctrines of the physicist and the physiologist about light rays and nervous discharges consists in the end of sense-experiences of physicists and physiologists, their “observations”. A sensation, such as one of sound, or colour, a feeling such as one of warmth or pain, a passion such as one of rage, are all impressions. His doctrine of impressions and ideas is intended to be a new and incontestable way of putting the empiricist position. The doctrine is stated and professedly proved as if it was equivalent to “Every simple image is derived from a corresponding sensation or passion”.
