Psi and the Physical World
FOR THE last two decades it has been possible to define the field of parapsychology in a clear-cut fashion as one that deals with phenomena not explainable by physical principles. There is a great part of mental life that may or may not be nonphysical, but parapsychology at the present stage is not concerned with effects for which the interpretation is ambiguous. In order to be considered as parapsychological the phenomena must be demonstrably nonphysical. That is, they must occur under conditions that clearly eliminate the types of operation known as physical. In their spontaneous occurrence the phenomena of parapsychology appear to defy physical explanation and when examined experimentally they can be proved to be beyond the reach of physical explanation. (We need hardly add that we are using terms and concepts in their current meanings; any other would be too conjectural for scientific use.)
It is a matter of history that the founding of this branch of science derived its initiative from the interest many scholars of the nineteenth century felt in discovering whether all nature was, as was assumed in the growing philosophy of materialism, a purely physical system. Are there mental processes that are not a part of the world of physics? In their search for an answer to this question the founders of parapsychology were looking for possible nonphysical phenomena in nature that might be scientifically observed and described.
To these early explorers reports of spontaneous thought-transference occurring between individuals separated by great dis