J. B. Rhine
Out of his sensory experience and its rational derivatives man has developed a general concept known as the physical universe. And out of the relationships that have been found to exist within this observed and inferred universe have emerged the recognized physical sciences and the physical bases of the other sciences. While from time to time there have been offered hypotheses of nonphysical factors in living organisms, none of these has ever become orthodox, either in biology or psychology. There are, therefore, no conventionally recognized nonphysical operations in the natural world, and, according to prevailing thought, any occurrence not fundamentally reducible to physical process would have either to be ignored or classed as supernatural (though such a category, too, is unacceptable in the sciences). Thus, even though many individual scientists have reservations on the point, nature has, in the sciences, come to be effectively synonymous with the physical universe.
There has been only one small branch of inquiry to make a scientific attack on the question of nonphysical causation in nature. This branch of inquiry logically is a division of psychological study and is known today as parapsychology (and by various other names such as psychical research, metapsychics, psychic science, etc.). Its problem-domain includes those natural occurrences (now called psi phenomena) which do not submit to
Reprinted from The Journal of Philosophy, volume 51 ( 1954), pp. 801-810, by permission of the author and editors.