The studies of Psychical Researchers must necessarily cover a very wide area which is bounded on the one hand by Physical science proper, on another by Philosophy, on a third by Psychology and on a fourth by Religion. With each of these subjects it has close relations and yet possesses features which serve to distinguish it from any of them.
Sir William Barrett writes as follows of the scope of Psychical Research:
"The subjects to be considered cover a wide range, from unconscious muscular action to the mysterious operation of our sub-conscious self; from telepathy to apparitions at the moment of death; from hypnotism and the therapeutic effects of suggestion to crystal-gazing and the emergence of hidden human faculties; from clairvoyance, or the alleged perception of objects without the use of the ordinary channels of sense, to dowsing, or the finding of under-ground water and metallic lodes with the so-called divining-rod; from the reported hauntings of certain places to the mischievous pranks of poltergeists (or boisterous but harmless ghosts whose asserted freaks may have given rise both to fetishism and fairies); from the inexplicable sounds and movement of objects without assignable cause to the thaumaturgy of the spiritualistic séance; from the scribbling of planchette and automatic writing generally to the alleged operation of unseen and intelligent agents and the possibility of experimental evidence of human survival after death."
(Psychical Research, p. 10).
In view of the heterogeneous nature of this list I do not think it practicable to frame any hard and fast definition of Psychical Research. Moreover certain of the phenomena which it once studied—such as Hypnotism—have been largely taken over by "orthodox" science, and others, such as Telepathy and Clairvoyance, although of great intrinsic interest and some relevance, may ultimately be regarded as comparatively remote from the main body of psychic phenomena.
Roughly speaking, the characteristic feature of the latter is a suspicion, or prima facie appearance, or allegation that they emanate from, or are in some way connected with the activities of extra-mundane intelligences—notably the "spirits of" the deceased.
It is this feature which has caused their rejection by the sciences with which they would naturally appear to be associated and although our studies may in many cases show that the appearance is wholly spurious it must be remembered that, until every phenomenon is so disposed of and relegated to its appropriate "orthodox" science, the ultimate problem of Psychical Research is largely a matter of the provision of answers to such questions as:—
"Is there any scientifically valid reason for supposing that Individual Human Personality survives bodily death?"
"If so, under what conditions does it persist?"
"What is the relation between these new conditions and those with which we are acquainted?"