Bohr, Physical Review, 48, 696-702 (1935):

Of course there is in a case like that considered no question of a mechanical disturbance of the system under investigation during the last critical stage of the measuring procedure. But even at this stage there is essentially the question of an influence on the very conditions that define the possible types of predictions regarding future behavior of the system. Since these conditions constitute an inherent element of the description of any phenomenon to which the term 'physical reality' can be properly attached we see that the argumentation of the mentioned authors does not justify their conclusion that the quantum mechanical description is incomplete.

Bohr, Nature, 136, 65 (1935):

I should like to point out, however, that the named criterion contains an essential ambiguity when it is applied to problems of quantum mechanics. It is true that in the measurements under consideration any direct mechanical interaction of the system and the measuring agencies is excluded, but a closer examination reveals that the procedure of measurements has an essential influence on the conditions on which the very definition of the physical quantities in question rests. Since these conditions must be considered as an inherent element of any phenomenon to which the term "physical reality" can be unambiguously applied, the conclusion of the above mentioned authors would not appear to be justified.

Bohr, p. 98 of "Atomic Theory and the Description of Nature" (1929), with my clarifications in brackets:

"The relativity of our perception of motion, with which we become conversant as children when traveling by ship or by train, corresponds to a common-place experiences on the reciprocal character of the perception of touch. One need only remember here the sensation, often cited by psychologists, which every one has experienced when attempting to orient himself in a dark room with a stick. When the stick is held loosely, it appears to the sense of touch to be an object. When, however, it is held firmly, we lose the sensation that it is a foreign body, and the impression of touch becomes immediately localized at the point where the stick is touching the body under investigation. It would scarcely be an exaggeration to maintain, purely from psychological experiences, that the concepts of space and time by their very nature acquire a meaning only because of the possibility of neglecting the interaction [our interaction] with the means of measurement. On the whole, the analysis of our sense impressions discloses a remarkable independence of the psychological foundations of the concepts of space and time, on the one hand, and the conceptions of energy and momentum, based upon actions of force, on the other hand. Above all, however, this domain, as already mentioned, is distinguished by reciprocal relationships which depend upon the unity of our consciousness and which exhibit a striking similarity with the physical consequences of the quantum of action. We are thinking here of the well-known characteristics of emotion and volition which are quite incapable of being represented by visualizable pictures. In particular, the apparent contrast between the continuous outward flow of associative thinking [the stream of consciousness] and the preservation of the unity of personality [perhaps according to Kant rather than James] exhibits a suggestive analogy with the relation between the wave description of the motions of material particles, governed by the superposition principle, and their indestructible individuality. [This analogy is between {the observer in world 7 and the extended observer in worlds 7-5} and {the observed in world 1 and the extended observed in worlds 1-3}!] The unavoidable influence on atomic phenomena caused by observing them here corresponds to the well-known change of the tinge of the psychological experiences which accompanies any direction of the attention to one of their various elements."


"tinge: 4) A slight admixture, as of some qualifying property or characteristic."

James, p. 206 of volume one (just prior to the "Stream of Thought" on p. 224):

"It must be admitted, therefore, that in *certain persons*, at least, *the total possible consciousness may be split into parts which coexist but mutually ignore each other*, and share the objects of knowledge between them. More remarkable still, they are *complementary*. Give an object to one of the consciousnesses, and by that fact you remove it from the other or the others."

James, p. 177 of volume two:

"The first thing that seems evident is that we have no *immediate* power of comparing together with any accuracy the extents revealed by different sensations. Our mouth-cavity feels indeed to itself smaller, and to the tongue larger, than it feels to the finger or the eye, our tympanic membrane feels larger than our finger-tip, our lips feel larger than a surface equal to them on our thigh. So much comparison is immediate; but it is vague; and for anything exact we must resort to other help.

"*The great agent in comparing the extent felt by one sensory surface with that felt by another, is superposition - superposition of one surface upon another, and superposition of one outer thing upon many surfaces*. Thus are exact equivalences and common measures introduced, and the way prepared for numerical results."

James, p. 171 of volume two:

"*The feeling of motion* has generally been assumed by physiologists to be impossible until the positions of *terminus a quo* and *terminus a quem* are severally recognized,... but we can only *infer* that which we already generically know in some more direct fashion, and it is experimentally certain that we have the feeling of motion given us as a direct and simple *sensation*."

Bohm, p. 154 of "Quantum Theory" (1951):

"In classical theory, and momentum can be expressed as functions of positions and velocities.... In quantum theory, however, the energies and momenta cannot be expressed in this way. Thus, classically, the momentum is defined as p = lim as delta t -> 0 of m delta x / delta t. But we have already seen that, in the quantum domain, this limit does not really exist when delta t is made too small. The only course that seems to be left open is to regard momentum as an independent physical property of matter...."

James, pp. 183-4 of volume two:

"*Whatever sensible data can be attended to together we locate together. Their several extents seem one extent. ...They become, in short, so many properties of ONE AND THE SAME REAL THING.* This is the first and great commandment, the fundamental 'act' by which our world gets spatially arranged.

"In this *coalescence in a 'thing'*, one of the coalescing sensations is held to *be* the thing, the other sensations are taken for more or less accidental *properties*, or modes of appearance. The sensation chosen to be the thing essentially is the most constant and practically important of the lot; most often it is hardness or weight."

James, from "The Stream of Thought" (the chapter that Bohr said he read), p. 285 of volume one:

"If the sensations we receive from a given organ have their causes thus picked out for us by the conformation of the organ's termination, Attention, on the other hand, out of all the sensations yielded, picks out certain ones as worthy of its notice and suppresses all the rest.

"Helmholtz says that we notice only those sensations which are signs to us of *things*. But what are things? Nothing, as we shall abundantly see, but special groups of sensible qualities, which happen practically or aesthetically to interest us, to which we therefore give substantive names, and which we exalt to the exclusive status of independence and dignity. But in itself, apart from my interest, a particular dust-wreath on a windy day is just as much of an individual thing, and just as much or as little deserves an individual name, as my own body does.

"And then, among the sensations we get from each separate thing, what happens? The mind selects again. It chooses certain of the sensations to represent the thing most *truly* and considers the rest as its appearances, modified by the conditions of the moment. Thus my table-top is *square*, after but one of an infinite number of retinal sensations which it yields, the rest of them being sensations of two acute and two obtuse angles; but I call the latter *perspective* views, and the four right angles the *true* form of the table, and erect the attribute squareness into the table's essence, for aesthetic reasons of my own."


If we wish to really understand it, we must trace Bohr's enigmatic response to Einstein in the Physical Review article of 1935 back to his own preliminary response in Nature and his earlier clue in "Atomic Theory and the Description of Nature", and from there back to the roots of Bohr's understanding in the work of William James. This final step is transparent, even from the texts, but we also have the excellent historical research of Henry Folse in "The Philosophy of Niels Bohr", which establishes that Bohr almost certainly made at least three serious studies of James, first in 1904, when his then tutor Harald Hoffding visited James in America, then in 1912 with Edgar Rubin and the Ekliptika Circle, as Bohr recollected one day before his death, and finally in 1932 with Leon Rosenfeld, as Rosenfeld clearly recollected.

The essential insight to be gained from this line of inquiry is into the meaning of "complementary" and "superposition". The essential conclusion is the psychological and phenomenological truth that of a bundle of related properties, gleaned from sensation, we inherently view one property as the thing itself and another property as the attribute of the thing. Thus if we define the thing in terms of the spacetime continuum (extensively), we will view energy and momentum as its (mental and physical) noumenal properties to be observed. If, on the other hand, we define the thing in terms of the new definition of motion (as holomovement), then we will view the pseudo-noumenal (or psycho-physical) aspect of space as the property to be observed.

James defines superposition in terms of these pseudo-noumenal (or psycho-physical) spaces. It might be thought that he is just talking about classical comparison between spatial surfaces of the body, but the context has to do with our internal construction of spatial relations, and this must be viewed, in the context of quantum measurement theory, as the observer's first person observation of his quantum brain. The spatial surfaces of the body as mapped onto the quantum brain constitute the physiological homunculus, as the agent of superposition. The philosophical homunculus, as the atomic soul pervading the quantum brain with the currents of consciousness, is the "indestructible individuality" of the atomic entity, and it has the same relation to the physiological homunculus that "the indestructible individuality of material particles has to the wave description of the motions of those material particles, governed by the superposition principle". QED.


The above argument proves that James' use of the terms "complementary" and "superposition" are indeed the foundations of Niels Bohr's philosophy and a quintessential clue to its meaning. But this does not exclude the Kantian perspective, as James thought, which the following remark by James and its refutation by Bohr, who sides with Kant, reveals:

James, reference to Kant in "The Stream of Thought", in a footnote on p. 274 of volume one:

"Many philosophers, however, hold that the reflective consciousness of the self is essential to the cognitive function of thought. They hold that a thought, in order to know a thing at all, must expressly distinguish between the thing and its own self.* [*Kant originated this view.] This is a perfectly wanton assumption, and not the faintest shadow of reason exists for supposing it true. As well might I contend that I cannot dream without dreaming that I dream, swear without swearing that I swear, deny without denying that I deny, as maintain that I cannot know without knowing that I know."

Bohr, p. 96 (ATDN):

"The epistemological problem under discussion may be characterized briefly as follows: For describing our mental activity, we require, on the one hand an objectively given content to be placed in opposition to a perceiving subject, while, on the other hand, as is already implied in such an assertion, no sharp separation between object and subject can be maintained, since the perceiving subject also belongs to our mental content. From these circumstances follows not only the relative meaning of every concept, or rather of every word, the meaning depending upon the arbitrary choice of point of view, but also that we must, in general, be prepared to accept the fact that a complete elucidation of one and the same object may require diverse points of view which defy a unique description."

The following quotes are also enigmatic keys, which may prove useful:

James, p. 275 of volume two:

"The essence of the Kantian contention is that there are not *spaces* but Space - one infinite continuous Unit - and that our knowledge of *this* cannot be a piecemeal sensational affair, produced by summation and abstraction." James, p. 175 of volume two:

"...*in the education of spatial discrimination the motions of impressions across sensory surfaces must have been the principal agent* in breaking up our consciousness of the surfaces into a consciousness of its parts.

"...*movement of surface under object is (for purposes of stimulation) equivalent to movement of object over surface)*."

Peter Joseph Mutnick 1949 - 2000