The logician recognizes the following propositional forms as necessary and sufficient for the expression of any truth:

The Bohr formulation—the original one—is now largely a matter of history. The usual career of a theory was its fate. It explained much, but it failed at the first signs of complication, even for the simplest molecules as hydrogen and helium. Some results were either only approximate in a loose or incomplete fashion, e.g. in the application of the correspondence principle to intensities, the only reliable predictions being only for an absence of certain lines, or they quite disagreed with experiment, e.g. in the case of the hydrogen molecule and the hydrogen molecule ion, the normal and excited states of helium, the anomalous Zeeman effect, the Ramsauer effect (the phenomenon of the deflection of electrons at low speeds being less than at higher speeds in atomic collisions), and in the treatment of problems where more than one electron was involved. In the last mentioned cases the perturbation method, so successful in solving “many-body” problems in celestial mechanics, failed completely because systems of several electrons, possessing frequencies of the order of light waves, cannot interact classically. A bit of much forced pragmatism was practiced in treating the many electron atom as a variation of the hydrogen atom. Besides, there were technical oddities, like ½ quantum numbers, and impenetrated anologies between visible and X-ray spectra.

Following the general program, outlined in a previous paper on the Foundations of Mathematical Biophysics, we shall outline some physico-mathematical aspects of the Gestalt-problem. Faithful to the principles laid down before, we shall not attempt to give a theory of such and such psycho-physiological phenomena connected with our problem, but we shall investigate in a preliminary way the abstract conceptual basis, which must underlie the construction of any concrete theory. To make our aim quite clear and to avoid at the same time unnecessary repetition, we refer the reader to our previous paper. Furthermore we shall give here only an outline of the physico-mathematical aspects; and of necessity we must leave a number of details untouched and unanswered.

The mind-body problem is—despite appearances—still the inevitable basic issue of unending discussions in recent philosophy. Various types of epistemologies and metaphysics, European and American, have offered their widely divergent “solutions” of the dreaded Cartesian tangle. Is there any hope of reaching a universally acceptable view?

There is a significant and a too little noted analogy between the histories of the physical and the “mental” sciences—especially psychology—an analogy capable of throwing much light upon the present-day problems of the latter. Some aspects of this analogy have become commonplaces, but others have been almost completely overlooked.

One of the interesting and encouraging signs of our times is the fact that the several sciences are learning to develop and carry their own philosophy. Here psychology seems to me to be a bit backward. In this paper I am presuming to suggest that the time has come when the psychologist should take over the subject of theory of knowledge, emancipate it from the leading-strings of Mother Philosophy, and make it a phase of his own science and of its organizing and interpretative philosophy. In fact, I am suggesting that thinking and knowing of whatever sort, even psychologizing and philosophizing, being matters of “mental” activity, are properly object matters for the psychologist, when he really knows his stuff; and I am presuming to say that he is now well enough advanced towards this goal so that he should accept this implied challenge and proceed to take possession of this most significant portion of his proper field. This should greatly enlarge the field of psychological experimentation; it should open up new areas, that are even more significant for our science than are animal psychology and the psychology of learning, as we have hitherto envisioned these; and it should result in a development of principles for the better organization of our findings in these fields.