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Bohm
on Perception and Metaphor in Scientific Discovery
For forty years following his initial 1952
statement of his hidden-variable interpretation Bohm
continued to expound his views in philosophy of
science, metaphysics, and epistemology.
His statements that are most relevant to the
subject of scientific discovery are found in Science, Order and Creativity, particularly in the introductory
chapter and in the two succeeding chapters, which
altogether take up about half of the book.
There he also sets forth his philosophy of perception, which is
explicitly opposed to that of the Logical
Positivists, and is characteristic of contemporary
post-Positivist philosophy of science. It also reveals some influence from Einstein, because he says
perception takes place in the mind and in terms of
theories. For
example the observational data obtained by
Archimedes in his bath had little value in
themselves. What
was significant was their meaning as perceived
through the mind in an act of creative imagination.
The principal historical change that has
occurred in modern science is that this mental
perception is more mediated through elaborate
instruments that have been constructed on the basis
of theories. Bohm's
philosophy of perception is central to his views on
scientific discovery and he assigns a special role
for metaphor.
Bohm believes that the development of science
is now obstructed by fragmentation that is caused by
subliminal rigidities in thought that he calls the
tacit infrastructure of scientific ideas.
One example of the tacit infrastructure of
scientific ideas is the Newtonian notions of space
and time that led Lorentz to preserve both the idea
of the constancy of the velocity of light and the
ideas of absolute space and time by explaining the
anomalous results of the measurements of light by
postulating changes in the measuring apparatus as
the apparatus moves through the ether. He notes that the tendency of the scientist's mind to hold to
what is familiar is reinforced by the fact that the
overall tacit infrastructure is interwoven in the
institutions on which depends the professional
security of the scientist.
The means for breaking out of the tacit
infrastructure of scientific ideas and to create new
theories is metaphor. Bohm defines metaphor as the
simultaneous equating and negating of two concepts.
Metaphor is especially important for Bohm, since he
maintained that microphysics and macrophysics should
have the same basic ontology, such that features
from the latter domain projected into the former
enables a discovery strategy. This role of metaphor
in discovery is possible because the realm of
physics is now that of perception through the mind,
and theory dominates experiment in the development
of the scientific perception of nature. Bohm says
that metaphor occasions creative perception, and he
also refers to metaphoric perception. Metaphoric
perception brings together previously incompatible
ideas in radically new ways.
He says that the unfolding of a metaphor that
equates different and even semantically
incommensurable concepts can be very fruitful.
In using the term incommensurable Bohm
references Kuhn, and he equates his own thesis of
the tacit infrastructure of scientific ideas with
Kuhn's thesis of scientific paradigm.
A paradigm is not just the articulate theory,
but also the scientist's whole way of working,
thinking, communicating, and perceiving with the
mind. However,
Bohm rejects Kuhn's thesis that normal science is
without any creativity, and that revolution is
completely discontinuous.
Bohm maintains that semantic
incommensurability can be overcome with metaphor. He furthermore says that revolution occurs when a new
metaphor is developed, and normal science is the
creative unfolding of that new metaphor.
In Bohm's view there is much more creativity
in normal science, than Kuhn admits. Bohm also criticizes Popper's thesis of falsifiability.
He maintains that today an excessive emphasis
is being placed on falsifiability in the sense that
unless a theory can immediately or very shortly be
falsified, then that theory cannot be regarded as
properly scientific.
A new idea with broad implications may
require a long period of gestation before
falsifiable consequences can be drawn from it.
Bohm also maintains that communication is
essential to perception in science.
He understands communication in a very broad
sense to include the individual's own articulate
mental dialogue with himself.
The scientist engages in an inner dialogue
with himself as well as with his colleagues, and in
this dialogue he is disposed in his thinking by the
social background. Insights enfolded in this inner dialogue must be unfolded by
discourse with colleagues and eventually by
publishing. Fragmentation
may proceed to the point that communication becomes
blocked, because the tacit infrastructure of ideas
not only limits the individual but also the whole
scientific community in their creative acts of
perception. Both
paradigms and specialization may cause fragmentation
in this way. One
very central thesis of Bohm’s is that a
fragmentation has occurred in modern microphysics
between mathematical formalism and informal
discourse in microphysics. Differences in the informal discourse gave rise to an issue
between Bohr and Einstein, as well as among later
physicists. Bohm
considers communication to be so central to
perception that he speaks of
perception-communication.
The change in the language of physics
occasioned by the development of quantum theory has
led to a communication breakdown. Both Bohr and
Einstein agreed on the mathematical formalism, but
there is still no common informal language.
Bohm believes that if Bohr and Einstein had
been willing to entertain a free dialogue to
eliminate the rigidities that block communication,
then perhaps a new creative metaphor might have
emerged for microphysics.
In such a dialogue each person must be able
to hold several points of view in a sort of active
suspension, while treating others' views with the
consideration he gives to his own.
This would lead to the intellectual free play
needed for a new creative metaphor.
Bohm proposes his hidden-variable
interpretation for consideration in this spirit.
He maintains that the interpretation of a
formalism is something that is in the informal
discourse, not in the measurements or the equations.
This view is fundamentally contrary to
Hanson's, who says the exact opposite.
In Bohm's view all the available
interpretations of the quantum theory, as with any
other physical theory, depend fundamentally on
implicit or explicit philosophical assumptions, as
well as on assumptions that arise in countless other
ways. The
image of the hard-nosed scientist, who does not
admit to the existence of the philosophical
assumptions in the informal language, is just
another example of the subliminal influence that is
exerted on scientists by the tacit infrastructure of
ideas shared by the scientific community at large.
Bohm
on Mathematics and Scientific Discovery
In Science,
Order and Creativity Bohm maintains that there
is no difference between science and philosophy.
While Hanson also states that physics is
natural philosophy, Bohm's statement means something
very distinctive.
Bohm explicitly rejects the prevailing view
of the aim of physics, which he says is to produce
mathematical formalisms that can correctly predict
the results of experiments.
He maintains that, since quantum theory and
relativity theory were never understood adequately
in terms of what he calls physical concepts, physics
gradually slipped into the practice of talking about
equations. And
he states that Heisenberg gave this practice an
enormous boost with the idea that science can no
longer visualize atomic reality in terms of physical
concepts, and with the idea that mathematics is the
basic expression of our knowledge of reality.
Bohm maintains that the current emphasis on
mathematics has gone too far. In stating that science is the same as philosophy, Bohm means
that as philosophy had traditionally done, now
science must unify knowledge instead of offering
physicists a fragmentation as it has today.
In times past there was a general vision of
the universe, of humanity, and of man's place in the
whole. But
specialization in modern science became narrower and
led eventually to the present approach, which is
fragmentary. Bohm
also opposes what he sees as another wayward aim of
modern physics, which is to analyze everything into
independent elements that can be dealt with
separately. This
further contributes to fragmentation. Bohm believes that the time has come to change what is meant
by science. This
change is to be implemented by a creative surge that
will eliminate the fragmentation.
In the fourteenth chapter of Undivided
Universe Bohm offers a somewhat more balanced
statement of the relation between physical concepts
and mathematical concepts.
Again he says that the prevailing attitude
today is take the present mathematical formalism of
quantum theory as an essential truth, and then to
try to derive the physical interpretation as
something that is implicit in the mathematics.
He denies that his own approach is simply a
return to the historically earlier view that the
mathematics merely enables the physicist to talk
about the physical concepts more precisely.
His view is that the two types of concepts
represent two extremes, and that it is necessary to
be in a process of thinking that moves between these
extremes in such a way that they complement one
another. He
says he does not regard such physical concepts as
particle, quantum wave, subquantum field, position,
and momentum as mere imaginative displays of the
meaning of the equations.
He maintains that what he is doing with his
hidden-variable interpretation, is moving to the
other side of the extreme in the thought process and
taking the physical concepts as a guide for the
development of new equations.
He says that the clue for a creative new
approach may come from either side, and may flow
back and forth indefinitely between them.
Bohm’s
Philosophy of Science
Aim of Science
Bohm’s
view of the aim of science contains a fundamental
ambiguity. One
aim is to supply a basically uniform and consistent
ontology for science admitting variations at
different orders of magnitude.
But it does not admit to the inconsistency or
pluralism that exists between quantum theory and
relativity theory, which Heisenberg called the
schism in physics, and which Bohm called
fragmentation.
This is the integrating aim that Bohm has in
mind when he says that physics is philosophy.
The other aim is the more conventional one in
contemporary physics, the aim of producing more
empirically adequate equations.
Bohm maintains that these two aims of science
need not and should not be divergent, even though
lamentably they presently diverge. And he says that
the fragmentation in contemporary physics is due to
an exclusive concern with the formal language, the
equations of mathematical physics.
Discovery
Bohm’s philosophy of scientific discovery
follows from these views on the aim of science.
The fragmentation-produced divergence between
these aims will be eliminated and
both aims will be more adequately realized, if
physicists attend to both the formal and the
informal language, to both the mathematical and
physical concepts.
Employing figures of speech such as analogy
and metaphor containing physical concepts will
facilitate developing better equations.
Criticism
Bohm’s views on scientific criticism do not
lead him to invalidate the empirical adequacy of the
Schrödinger wave function.
Like other critics of the Copenhagen
interpretation he advocates developing an
alternative interpretation for the equations of the
quantum theory.
He never denies that the second aim of
science, the production of empirically superior
equations, is realized by the equations of the
quantum theory.
But just as there is an ambiguity in his aim
of science, so too there is a corresponding dualism
in his criteria for scientific criticism.
He spent most of his career attempting to
persuade the physics profession that there exists
another criterion that is unabashedly philosophical.
That criterion is the integrated, consistent
ontology for both microphysics and macrophysics. And some physicists like John Bell have been persuaded to
pursue this agenda.
Explanation
Bohm does not set forth an explicit statement
of his philosophy of scientific explanation.
But if satisfaction of the criteria for
scientific criticism is taken as yielding a
scientific explanation, then Bohm’s philosophy of
scientific explanation follows from his views on
criticism. The
salient consideration in this context is the role
for a uniform and consistent ontology in his
integration aim of science and its associated
criterion for scientific criticism.
Hanson
on the Copenhagen Interpretation and Scientific
Discovery
Hanson rejects all three of the objectives in
Bohm's agenda for future physics. His argument against Bohm's third objective that a future
hidden-variable theory will resolve the difficulties
in current quantum theory, is that Bohm and other
advocates of alternatives to the Copenhagen
interpretation offer nothing but promises.
In Quanta
and Reality Hanson calls Bohm's proposal a
congeries of excitingly vague,
bold-but-largely-formless,
promising-but-as-yet-unarticulated speculations. The Copenhagen interpretation on the other hand is a working
theory however imperfect it may be, and a
speculation is never an alternative to a working
theory.
Hanson's argument against Bohm's first
objective that an alternative to the Copenhagen
interpretation is possible, is similar to his
criticism of the third objective. Hanson denies that an alternative to the Copenhagen
interpretation is possible until a new mathematical
quantum theory formalism is developed, because on
his thesis the Copenhagen interpretation is not a
semantics supplied by related philosophical or
metaphysical ideas about the subject, but rather is
the semantical interpretation resulting from the
logicogrammatical form of the theory’s
mathematical formalism.
Therefore contrary to physicists such as Bohm
and Lande, and contrary to philosophers such as
Feyerabend and Popper, the Copenhagen interpretation
even after disengagement from what Hanson calls
Bohr's naive epistemology, is not just one of
several alternative semantical interpretations; it
is a unique interpretation that is defined by the
relationships in the mathematical formalism.
In Concept
of the Positron and elsewhere Hanson
distinguishes the Copenhagen interpretation from
what he calls the Bohr interpretation.
He rejects efforts by philosophers such as
Feyerabend to include what Feyerabend admits are the
dogmatic elements of the Bohr interpretation in the
Copenhagen interpretation.
The dogmatic elements consist particularly in
what Hanson calls Bohr's naive epistemology with its
forms of perception.
Perhaps it could be said with caution that
with the rejection Bohr's naive epistemology
Hanson's philosophy of quantum theory is one that
Heisenberg might have formulated, had Heisenberg
rejected Bohr's epistemological ideas which he
included in his doctrine of closed-off theories, and
instead followed through on Einstein's admonition
that theory decides what the physicist can observe.
With his rejection of the Bohr interpretation
Hanson places himself in agreement with Bohm and
Feyerabend, when the latter maintain that the
quantum theory is not permanently valid, and he
agrees that the current quantum theory may be
superseded. But
contrary to these authors he considers the
wave-particle duality to be the defining
characteristic of the Copenhagen interpretation and
integral to the formalism.
Because he maintains that the Copenhagen
interpretation is defined by the logicogrammatical
form of the mathematical formalism itself, he
defends it as the only interpretation that works.
He therefore says that in the absence of any
algebraically detailed and experimentally adaptable
alternative, the Copenhagen interpretation
represents the conceptual possibilities currently
open to practicing physicists, and that it will not
be abandoned until it is completely replaced by an
alternative, completely detailed, algebraically
articulated theory.
Bohm's second objective in his agenda for
future physics is that the history of physics
suggests (contrary to a mechanistic thesis, as he
uses that term) that the future microphysical theory
will describe phenomena at the lower level of
magnitude than does the current quantum theory, and
that his proposal of a hidden-variable theory of the
subquantum level may serve as a heuristic for future
microphysics. The
idea of developing a heuristic for future scientific
discovery or theory development is closely related
to Hanson's interest, and Hanson does not attack
Bohm's second objective in terms of Bohm's
antimechanistic historical thesis.
But he has his own historical thesis
influencing his views on scientific discovery.
His analyses are greatly influenced by the
Cambrian physicist Paul A. Dirac. Dirac (1902-1984) was a theoretical physicist at Cambridge
University, who shared the Nobel Memorial Prize for
physics in 1933 with Schrödinger.
Dirac had published a methodological
statement on the future of physics in his "The
Evolution of the Physicist's Picture of Nature: An
account of how physical theory has developed in the
past and how, in the light of this development, it
can perhaps be expected to develop in the
future" (Scientific
American, May, 1963).
In this brief paper Dirac contrasted the
theory development approaches of Schrödinger and
Heisenberg. Dirac
was much more sympathetic to the former's approach,
according to which the development of physical
theory should be guided by the aesthetics of the
mathematics of the theory, in contrast to the
latter's approach in which a mathematical formalism
is developed by data analysis.
However, this is not the issue in Dirac's
views that influenced Hanson, who was actually much
more sympathetic to Heisenberg's approach in which
theory originates with the experimental data.
Hanson was influenced by Dirac's historic
accomplishment, the transformation theory developed
by Dirac in 1928, which not only combines relativity
and quantum mechanical descriptions of electron
properties, but also enables physicists to exhibit
the wave-particle duality by transforming
mathematically the wave description into the quantum
description and vice versa.
Both in his "Copenhagen Interpretation
of Quantum Theory" in the American
Journal of Physics (1959) and in his chapter
"Interpreting" in Concept
of the Positron, Hanson states that objections
to the Copenhagen interpretation arise from a
failure to appreciate the historical and conceptual
role it had played in Dirac's 1928 paper, and he
reports that in conversation with Dirac, Dirac told
him that the Copenhagen interpretation figured
essentially in his development of his relativistic
quantum field theory, and not as merely a
philosophical after-thought appended to the
mathematical formalism.
This personal conversation with Dirac more
than anything explains Hanson’s motivation for
maintaining that the Copenhagen interpretation is
integral to the formalism of the quantum theory.
He argues against Feyerabend that even if it
were possible to have a minimum statement of quantum
theory with no more interpretation than is required
barely to describe the facts, this is what Dirac
felt he had, and Dirac's paper would not have been
the paper that it actually was, had its assumptions
been purified of the Copenhagen interpretation, as
Feyerabend advocates.
But for his thesis of scientific discovery
Hanson turned not to Dirac’s aesthetic thesis, but
to the logical thesis proposed by the founder of
Pragmatism, Charles S. Peirce.
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