CLAIRVOYANCE (Fr. for " clear-seeing ")  , a technical term in psychical research, properly equivalent to lucidity, a super-normal power of obtaining knowledge in which no part is played by (a) the ordinary processes of sense-perception or (b) super-normal communication with other intelligences, incarnate, or discarnate . The word is also used, sometimes qualified by the word telepathic, to mean the power of gaining supernormal knowledge from the mind of another (see TELEPATHY) . It is further commonly used by spiritualists to mean the power of seeing spirit forms, or, more vaguely, of discovering facts by some supernormal means . Lucidity.—Few experiments have been made to test the existence of this faculty . If communications from discarnate minds are regarded as possible, there are no means of distinguishing facts obtained in this way from facts obtained by independent clairvoyance . In practice no evidence has been obtained pointing to the possession by a discarnate spirit of knowledge not possessed by any living person (see MEDIUM) . As explanation of the few successful experiments in independent clairvoyance we have the choice of three explanations: (1) lucidity; (2) telepathy from living persons; (3) hypereesthesia . The second possibility was overlooked in Richet's diagram experiments; it cannot be assumed that a picture put into an envelope and not consciously recalled has been in reality forgotten . Similarly the clairvoyant diagnosis of diseases may depend on knowledge gained telepathically from the patient, who may be subliminally aware of diseased states of the body . The most elaborate experiments are by Prof . Richet with a hypnotized subject who succeeded in naming twelve cards out of sixty-eight . But no precautions were taken against hyperaesthesia further than enclosing the card in a second envelope .

There is a power possessed by a certain number of

people, of naming a card drawn by them or held in the hand face downwards, so that there is no normal knowledge of its suit and number . Few thorough trials have been made; but it seems to point to some kind of hyperaesthesia rather than to clairvoyance; in the Richet experiments even if the envelopes excluded hyperaesthesia of touch on the part of the medium, there may have been subliminal knowledge on Prof . Richet's part of the card which he put in the envelope . The experience known as the dejd vu has sometimes been explained as due to clairvoyance . Telepathic Clairvoyance.—For a discussion of this see TELEPATHY and CRYSTAL-GAZING . It may be noted here that some curious relation seems to exist between apparently telepathic acquisition of knowledge and the arrival of a letter, newspaper, &c., from which the same knowledge could be directly gained . We are confronted with a similar problem in attempting an explanation of the power of mediums to state correctly facts relating to objects placed in their hands . Of a somewhat different character is retrocognition (q.v.), where the knowledge in many cases, if telepathic, must be derived from a discarnate mind . Clairvoyance, as a term of spiritualism, with its correlative clairaudience, is the name given to the power of seeing and hearing discarnate spirits of dead relatives and others, with whom the living are said to be surrounded . More vaguely it includes the power of gaining knowledge, either through the spirit world or by means of psychometry (i.e. the supernormal acquisition of knowledge about owners of objects, writers of letters, &c.) . Some evidence for these latter powers has been accumulated by the Society for Psychical Research, but in many cases the piecing together of normally acquired knowledge, together with shrewd guessing, suffices to explain the facts, especially where the investigator has had no special training for his task . See Richet, Experimentelle Studien (1891); also in Proc .

S.P.R. vi . 66 . For a

criticism see N . W . Thomas, Thought Transference, pp . 44-48 . For Clairvoyance in general see F . W . H . Myers, Human Personality, and in Proc . S.P.R. xi . 334 et seq .

For a criticism of the evidence see Mrs

Sidgwick in Proc . S.P.R. vii . 30, 356 . (N . W .