About one-half century following turmoil in physics, a similar dispute occurred in psychology over what concepts are acceptable. In all disciplines concepts should be measurable in an objective time and space. Their usefulness depended upon how well they portended or explained future events. Logical errors of dualism occurred whenever events metaphysical, i.e., unobservable, were linked by cause to events observable. Logical errors of reductionism occurred when events described with molecular constructs were seen as basic to or causing events described in more molar terms.

Psychology is different from the other disciplines of science in that it not only has a specialized reporting language as part of the scientific end product but also the full spectrum of language as part of the initial subject matter. Psychology is the same as the other disciplines of science in that the investigators have a fraction of their observation where they can reach consensual agreement with fellow observers and a portion that is privy only to themselves as individuals. This portion of each person’s private experience cannot be breeched. If an observer attempts to share with another his or her private world, it immediately becomes verbal report. That portion not shared from the other may be correctly guessed, fraudulently guessed, or remaining unknown. From these fractions come the majority of logical errors in science.