Original Source
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Extension of Complementarity
Niels Bohr's overriding concerning in his writings from 1935 to his death in
1962 was to bring the lessons of complementarity to fields other than atomic
physics. But Bohr's success in describing the atomic system worked against
him, in a way, and his point that complementarity teaches a lesson about the
use of concepts for describing all phenomena was largely ignored.
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Since all the sciences aspire to unambiguous communication of phenomena based
on observation, such a discovery as complementarity affects all the sciences.
In the classical framework, it was considered to be a criterion of objective
description that the properties ascribed to the object were possessed by it
quite apart from the observational interaction on which the description was
based. According to complementarity though, the individuality of the
interaction means the properties of the phenomenal object exist only in
relation to the specific agencies of observation that produced the phenomena.
The description is unambiguous (i.e., "objective") only when it includes a
full description of the agencies of observation which produced the phenomenon.
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Classically, one could make a determination of the state of a physically
isolated system the criterion of objective description only if such a
description could be regarded as pictures of the properties of an independent
reality existing apart from the observation. Such an ideal is only possible
where either the causal effect of the observation could be "controlled" or
could be considered negligible. By abandoning the classical point of view,
complementarity used two distinctive modes of observation, each pursuing a
goal necessary for the employment of the other.
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Complementarity in Anthropology
Although the role of an anthropologist doing field research on a primitive
tribe is not how Bohr attempted to portray complementarity, it illustrates his
ideas very well. In the case of an anthropologist from an "advanced" culture
observing the behavior of a hitherto isolated tribe, his presence may well
affect the tribe in ways which are neither negligible nor can be controlled.
And if he describes just what he observes, his description is ambiguous
because another anthropologist coming under different circumstances may well
alter the tribe's behavior in a different way, which again will be neither
negligible nor controllable. Complementarity tells us that neither description
is a description of the "real" tribe as it exists apart from these
observations.
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What both describe is the phenomenal tribe and its behavior patterns under
different specific observational circumstances. In order to apply both
descriptions to the tribe, the anthropologist must develop causal principles
to enable a determination of how such an outside influence affects the tribe's
behavior, and then by applying these causal principles, it can be predicted
just how the presence of the anthropologists effected the behavior of the
tribe as it was prior to their arrival.
The lesson of complementarity is that a well defined representation of the
tribe is not a picture of an independently existing tribe, but rather an
abstraction necessary for the unambiguous use of descriptions of that tribe.
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Complementarity in Psychology
Bohr never put his ideas in writing and his only account of them is far from
clear. In his university days his interest was aroused by the problem of
discussing human consciousness processes, particularly when it touched upon
freedom of the will. In his last interview, Bohr said:
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At that time I really thought to write something about philosophy, and that
was about this analogy with multivalued functions. I felt that the various
problems in psychology - which were called the big philosophical problems, of
the free will and such things - that one could really reduce them when one
considered how one really went about them, and that was done on the analogy to
multivalued functions. [1]
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His basic scheme seemed to be like this. When attempting to describe one's own
consciousness, i.e., the consciousness one experiences directly, one must make
a distinction between that consciousness as an object of description and the
subject consciousness that describes it. This is essentially the same as
Kant's distinction between empirical and transcendental egos. All attempts to
describe the experiencing subject in its experiencing activity necessarily
elude the grasp of the descriptive concepts. As soon as one begins to describe
that experience, it becomes the object of experience, thereby shifting the
distinction between experiencing subject and experienced object.
The theory of complex functions is one area of mathematics where multivalued
functions arise. Each complex number can be represented unambiguously on a
two-dimensional plane, but the multivalued functions have potentially an
infinite number of values, each a complex number and each a complex variable
value. G.F.B. Riemann proposed mapping such functions as different "branches"
of a single curve, each on a different plane, and each one representing the
curve of a single value function. In this case, as long as the curve is
followed in the same plane, the function can be mapped continuously without
ambiguity arising in the point number relationship.
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However, for each function the origin point is a "singular point" resulting in
the consequence that when a closed curve is traced around the origin, such
that it returns to the same value of the independent variable, the value of
the function now differs by a constant factor. For this reason, each time a
singular point is orbited, the value of the function must be represented in
another plane. Turning this into an analogy of the description of
consciousness, Bohr writes:
The analogy is this, that you say that the idea of yourself is a singular in
our consciousness. Then you find - now it is really a formal way - that if
you bring this idea (i.e., the idea of the experiencing subject) in, then
you leave a definite level of objectivity or subjectivity. For instance,
when you have to do with the logarithm, then you can go around; you can
change it by 2(pi) when you go one time around a singular point. But then
you can surely, in order to have it properly and be able to draw conclusions
from it, will have to go all the way back again in order to be sure that the
point is what you started on. Now I'm saying it a little badly, but I will
go on. That is then the general scheme, and I felt so strongly that it was
illuminating for the question of free will, because if you go round, you
speak about something else, unless you really go back again [the way you
came]. That was the general scheme you see. [2]
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The details are lacking, but Bohr seems to have intended to correlate the
relationship between the independent complex variable and the different values
of a multivalued function with a descriptive term and the different references
the term could have. Riemann had proposed eliminating this mathematical
ambiguity of a point on a single plane representing many possible values of a
complex function by turning the multivalued function into a series of single
valued functions represented on different planes. So Bohr proposed that the
different references of a term refer to different "planes of objectivity",
each analogized to a different meaning imparted to the "object" of the
experience as a consequence of different ways of drawing the distinction
between experiencing subject and experienced object. The chance for ambiguity
arises if we fail to note that when we trace a closed circle around a singular
point of the origin, we must move to a different plane.
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Bohr intended to say that the attempt to describe the self is like drawing a
closed curve around a singular point. The concept of self is then analogized
to a multivalued function, which may take on different meanings. Bohr felt
that in attempting to describe the subject self (transcendental ego), we must
"map" that meaning onto one plane of objectivity, but in doing so we make that
subject self the object and thus effectively shift the subject/object
distinction. When we return to the subject self, it is not the same self as
was the subject before we began to describe it. We must recognize that the
reference of the term "self" has moved to another plane of objectivity. Any
description unheedful of this fact runs the risk of having its terms slip from
one plane to another, thereby producing ambiguity.
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Bohr explored this line of thought well before he conceived of
complementarity, yet his early approach falls perfectly in line with his
epistemological lesson of complementarity, and he concluded his Como paper
like this:
I hope, however, that the idea of complementarity is suited to characterize
the situation, which bears a deep-going analogy to the general difficulty in
the formation of human ideas, inherent in the distinction between subject and
object. [3]
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And in the first paper he wrote after Como, he begins by referring to the
last sentence of his Como paper and then continues with probably his most
revealing description of complementarity as a general
epistemological lesson:
...For describing our mental activity, we require, on 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 subject and object 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 our
arbitrary choice of viewpoint, 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 necessity of taking recourse to a complementary, or
reciprocal, mode of description is perhaps most familiar to us from
psychological problems. [4]
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Bohr draws an analogy between "the unity of our consciousness" and the
"physical consequences of the quantum of action" which makes for the
individuality of the atomic system. Using the term "emotion" to refer to the
immediate subjective feeling of freedom, and "volition" to refer to that which
is objectively described in the act of willing, he points to the "suggestive
analogy" between these concepts as employed in the two different modes of
describing the act of willing in psychology, and the two modes necessary for
describing an object in physics. Just as the incautious use of concepts as
classically understood causes a misunderstanding of the problem of
wave-particle dualism, so too, the "problem of free will" is created by
assuming that "one and the same" object is being described.
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Bohr argued that this use of complementary terms for describing consciousness
is a feature of language where different contexts imply different ways of
drawing the distinction between subject and object. He writes:
Actually, ordinary language, by its use of such words as thoughts and
sentiments, admits [a] typical complementary relationship between conscious
experiences implying a different placing of the section line between the
observing subject and the object on which attention is focused. ...In fact,
the varying separation line between subject and object, characteristic of
different conscious experiences is the clue to the consistent logical use of
such contrasting notions as will, conscience and aspirations, each referring
to equally important aspects of the human
personality. [5]
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This "clue" should make it clear that Bohr regarded it as necessary to combine
the mode of description of introspective, rational psychology with the mode of
naturalistic, empirical psychology in order to present an unambiguous
description of all "equally important aspects of human personality". For
further reading, see
The Contributions of Humberto Maturana to the Sciences of
Complexity and Psychology
by Alfredo B. Ruiz.
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Bohr and
William James
Bohr's references to such terms as "unity of consciousness" and "change of
tinge" suggests that his thoughts were influenced by the writings of William
James. Though the date of Bohr's reading of William James is disputed, a
familiarity with James' Principles of Psychology is apparent as early as 1929.
Bohr was anxious that his comments about the concept of free will in
describing consciousness were not understood as asserting a dualistic view of
a causal influence between a non material "mind" and the physiological
organism. For Bohr, complementarity was relevant only in the descriptions of
physical interactions and not presumed psycho-physical interactions of a
dualistic metaphysics impossible to describe physically. He appropriated the
term "mysticism" in referring to such dualistic metaphysical doctrines. Bohr
wrote:
...the linkage of the atomic phenomena and their observations, elucidated by
the quantum theory compel[s] us to exercise a caution in the use of our
means of expression similar to that necessary in psychological problems
where we continually come upon the difficulty of demarcating the objective
content. Hoping that I do not expose myself to the misunderstanding that it
is my intention to introduce a mysticism which is incompatible with the
spirit of natural science. I may perhaps in this connection remind you of
the peculiar parallelism between the renewed discussion of the principle of
causality and the discussion of a free will which has persisted from
earliest times. Just as freedom of the will is an experiential category of
our psychic life, causality may be considered as a mode of perception by
which we reduce our sense perceptions to order. At the same time, however,
we are concerned with idealizations whose natural limitations are open to
investigation and which depend upon one another in the sense that the
feeling of volition and the demand for causality are equally indispensable
elements in the relation between subject and object which forms the core of
the problem of knowledge. [6]
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Bohr did not endorse the view of some physicists that the advent of
indeterminacy at the quantum level destroys the causal chain on which the
arguments for a bio-physical determinism rests. He constantly emphasized the
indispensability of a category of causality for the ordering of our psychic
life, which the insistence on absolute indeterminism would turn into chaos.
Several points in this application of complementarity to psychology are
hallmarks of complementarity analysis of empirical knowledge in general.
First, what has been understood as a problem of reality, are electrons
"really" particles or waves, is understood as a problem in the use of concepts
for describing different aspects of experience.
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Second, two modes of description are needed. To make a description objective,
i.e., to describe the object unambiguously, the object is described as
interaction with the subject, but to make this unambiguous, a second mode of
description must be combined with the first, this one describing the object as
isolated from observing interaction. In describing these two modes, the
descriptive terms must be understood as abstractions and not pictures of an
independent reality.
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Third, unambiguous descriptions must distinguish between the observing agency
and the observed object. This distinction may be drawn at any point, making it
possible to define the phenomena as a different description on a different
plane of objectivity. To avoid any ambiguity, the description of each
phenomenal object must specify how the distinction between observed object and
agency of observation has been drawn. Failing to do this renders the
observation ambiguous due to the implicit but illicit shift of the
subject/object distinction.
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Fourth, a failure to be sensitive to such ambiguities will give rise to the
appearance of genuine metaphysical problems about the nature of reality, which
disappear once the complementaristic analysis is employed. Problems such as
particle/wave dualism are not metaphysical conflicts about the nature of
reality, but rather these problems are confusions created by failure to
realize that such different descriptions refer not to the same object, but to
complementary phenomena which only together provide an unambiguous description
of reality.
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Fifth, the expansion of our understanding of reality made possible by the
framework of complementarity occurs not through the invention of newer, more
sophisticated concepts for describing experience, but rather through the
understanding the conditions required for unambiguous employment of
descriptive concepts.
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Complementarity in Biology
Bohr's father was deeply involved in the dispute between mechanism and
vitalism in biological descriptions, a burning issue in the late nineteenth
century. Bohr considered his own attempt to resolve this dispute to be in some
way a repayment of the intellectual gifts from his father, and so he derived
great satisfaction over this particular use of complementarity. Of all his
discussions of complementarity outside of atomic physics, the application to
biology was the most recurrent and the only one he worked out in any detail.
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Bohr was anxious to avoid supporting the version of vitalism which argued that
organic systems possess a "vital stuff", some sort of nonphysical entity which
inorganic objects do not possess. He warned sternly against any
metaphysical defense for finalistic descriptions in biology, maintaining
that organic objects are no more than complex physical systems.
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...this view, often known as vitalism, scarcely finds it proper expression in
the old supposition that a peculiar vital force, quite unknown in physics,
governs all organic life. I think we all agree with Newton that the real basis
of science is the conviction that Nature under the same conditions will always
exhibit the same regularities. Therefore, were we able to push the analysis of
the mechanism of living organisms as far as that of atomic phenomenon, we
should scarcely expect to find any features differing from the properties of
inorganic matter. [7]
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Bohr pointed out that the progress of atomic physics revealed "the unsuspected
discovery of an essential limitation of the mechanical description of natural
phenomena". The limitation here is not that of the uncertainty principle, but
rather that imposed by the need to accept the quantum postulate in order to
describe the atomic system. Bohr seemed to regard the atomic property of
stability, which is destroyed by observing the system, as analogous to the
organism's property of "life", which is destroyed by observations necessary
for a mechanical description of its internal processes.
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On one hand, a description of an organ within an organism is possible, but
this requires that the organism be described as an isolated system. However,
such isolation precludes describing it as "living", for that concept refers to
the organism's interaction with its surroundings. On the other hand, a
description of a living organism is possible by describing the interactions of
the organism with its environment, including the observing system. Since the
observing system necessary for observation must now fall on the object side of
the observer/observed distinction, the object described in the vitalistic mode
of description is a different object from the one describing the mechanical
mode. Since the physical conditions necessary for the two modes are exclusive,
they cannot be simultaneously employed, but they both must be used for a
complete description of a living organism.
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Quantum effects do play a role in biochemical processes at the molecular
level, but this was not the basis of Bohr's application of complementarity to
biological descriptions. The feature of "individuality" at the inorganic
atomic level parallels that in biological systems as life at the organic
level. Bohr writes:
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...it must be stressed that an account, exhaustive in the sense of quantum
physics, of all the continually exchanged atoms in the organism not only is
infeasible but would obviously require observational conditions incompatible
with the display of life. However, the lesson with respect to the role which
the tools of observation play in defining the elementary physical concepts
gives a clue to the logical applications of notions like purposiveness foreign
to physics, but lending themselves so readily to the description of organic
phenomena. Indeed, on this background it is evident that the attitudes termed
mechanistic and finalistic do not present contradictory views on biological
problems, but rather stress the mutually exhaustive observational conditions
equally indispensable in our search for an ever richer description of life.
[8]
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Bohr did not hold that a mechanistic description of the interaction between
the organism and its surrounding environment was impossible. Quite the
contrary, such an account is not only possible, it is necessary for a complete
description. His point was that in order to describe such interactions
unambiguously, the state of the interaction must be defined in isolation.
Attempts to do this arbitrarily cuts off the organism from the systems
necessary to support life, destroying the physical conditions necessary for
the display of the vital phenomena. And since the observing system and the
observed organism do not form an indivisible whole, as they do in quantum
interactions, it is possible to take into account the effects of the
observational interactions. He writes:
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The basis for the complementary mode of description in biology is not
connected with the problems of controlling the interaction between object
and the measuring tool, already taken into account in the chemical kinetics,
but with the practically inexhaustible complexity of
the organism. [9]
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What cannot be done, because of the "practically inexhaustible complexity of
the organism", is to define its state apart from its living environment. Bohr
saw progress in biology advancing on two distinct complementary fronts. One
front is the level of biochemical descriptions of the physical mechanisms
responsible for the various phenomena manifested at the sub-cellular level;
the other on the level of the organism as a whole and its interacting role
within larger systems essential to maintaining the organism's life.
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For an excellent complementarity viewpoint of biology, please read this paper
entitled The Biology of Language; The Epistemology of Reality by
Humberto R. Manturana, as well as Pitfalls, Risks and Challenges in
Teaching Biology of Cognition by Juan-Carlos Letelier, Fernando Leniz and
Francisco Bascu¤an.
This ends Part 6 of the review. Thanks for reading!
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Footnotes
[1] Bohr's Last Interview, Page 1
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[2] Ibid., Page 2
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[3] Bohr, Atomic Theory and Description of Nature
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[4] Bohr, The Quantum of Action and the Description of Nature
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[5] Bohr, Physical Science and the Study of Religions
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[6] Bohr, Causality and Complementarity
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[7] Bohr, Light and Life
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[8] Bohr, Physical Science and Problems of Life
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[9] Ibid.
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The Framework of Complementarity
Part 1 - Overview Early Years Bohr Formulates Complementarity
Part 2 - Argument for Complementarity
Part 3 - Comments on Complementarity
Part 4 - Complementarity and the Uncertainty Principle
Part 5 - Refinement of Complementarity
Part 6 - Extension of Complementarity
Part 7 - The Nature of Empirical Knowledge
Part 8 - Complementarity and the Metaphysics of Quality