# KARL POPPER AND FALSIFICATIONIST CRITICISM

## BOOK V - Page 3

Lande rejects subjective interpretations, and
states that quantum physics deals with records of
instruments rather than any observer's
consciousness, with physical objects rather than
mental pictures, and with statistical distributions
rather than lack of knowledge by human observers.
Knowledge and conscious reading by observers
are as irrelevant in atomic physics as they are in
any other branch of physical science.
Echoing Einstein's programmatic aim of all
physics (but without referencing Einstein), Lande
says that the object of natural science is to
suppose that the real world exists without human
advice and consent, and then to search for general
regularities which may help to manipulate things
and events.
The significance of all that quantum theory
stands for, is to provide formulas, tables, and
other rules of correlation between events, and in
particular between probabilities of transition.
To speak of the contraction of the wave
packet upon an observation is as senseless in
Lande's opinion as to speak of a sudden contraction
of a statistical mortality table upon an individual
fatality.
A probability wave does not guide actual
events any more than a mortality table guides actual
mortalities, and it shrinks no more than a mortality
table shrinks when an actual death occurs.
In Lande’s view the subjectivist confusion
begins when the material body used as a measuring
instrument is regarded as a subject, and when it is
then said that quantum theory has changed the
relation between subject and object.
This makes a great impression on those who
mistakenly identify statistical distributions
recorded by instruments with knowledge or lack of
knowledge of observing subjects.

Lande advances a particle interpretation of
the Heisenberg uncertainty relations and the Schrödinger
wave function, and he criticizes the Copenhagen
dualistic interpretation.
A central part of his criticism is his
alternative interpretation of the two-slit
diffraction experiment, in which the diffraction
pattern is construed by the Copenhagen school as
an interference pattern, that must be taken as
evidence for the wave nature of the electron, which
in turn must also be construed as a particle before
its entry into the slit and then again upon its
impact on the photographic plate.
Lande references the Stern-Gerlach experiment,
the theory of William Duane (1923), and the work of
Paul Ehrenfest and Paul S. Epstein (1924). He
explains that Duane's quantum theory was not
immediately recognized as a way out of the
Copenhagen duality paradox, because Duane’s proposed
statistical particle theory of diffraction pertains
to X-rays in support of the photon theory of light,
and also because in 1923 diffraction of electrons
was not yet discovered.
Lande references a letter written to him by
Born stating that Duane's 1923 paper on the particle
theory of X-ray diffraction was well appreciated at
the time of its publication, and stating that it is
a riddle as to why its significance was overlooked
when the diffraction of matter was discovered a few
years later.
Lande remarks that he could not find any hint
of recognition in any of the works of Bohr, Born, de
Broglie, Dirac, Einstein, Heisenberg, Pauli, or Schrödinger,
that Duane's quantum rule is relevant to the
alleged dilemma of matter diffraction and duality.

According to Duane's quantum rule for linear
momentum, the incident matter particles do not
spread out as continuous matter waves or manifest
themselves as though they do.
It is the crystal slit with its parallel
lattice planes, which is already spread out in
space, and which reacts as one rigid mechanical body
to the incident particles, that produces the
diffraction pattern.
Duane's rule yields the same observed
diffraction directly without appealing to any wave
interlude.
Therefore, the idea of a dualistic change
from matter particles to waves and then back to
particles is a quite unnecessary and fantastic
invention in Lande's opinion.
According to his criteria for scientific
criticism the scientific value of a theory is
measured not only by its power to account for
observed data, but also by criteria of simplicity,
freedom from *ad
hoc* assumptions, and reducibility to more
general postulates.
As a result of Duane's theory, quantum
physics has discovered that even such wave-like
phenomena as matter diffraction through crystals can
be understood in a consistent unitary way as
produced exclusively by matter particles obeying the
conservation laws of mechanics under special
restrictions known as quantum rules, matter
particles which react to bodies containing periodicies
in time and space.
Lande thus states that electrons always
behave as particles, and never misbehave as waves;
he calls Duane's quantum rule the "missing
link" between wave-like appearances and
particle reality.
To the two recognized general quantum
postulates, Planck's rule for energy exchange and
Sommerfeld-Wilson's rule for angular momentum
exchange, Lande adds Duane's quantum rule for linear
impulse changes as the third postulate for quantum
physics.
Lande thus answers the problem of the
two-slit diffraction experiment, the problem of
which of the two slits did the particle pass
through: he states that for its contribution to the
diffraction pattern, it does not make any difference
where exactly the diffraction takes place.
The electron changes its momentum in reaction
to the harmonic components of the matter
distribution of the crystal screen with two slits as
a whole.
All that matters is the conservation of
charge and of total momentum in the reaction between
electron and diffractor.

For these reasons Lande maintains that the
Copenhagen school starts from "wrong
physics", when they maintain that wave-like
appearances of matter diffraction are due to the
periodic wave action of the electron.
The correct view is that the appearances are
due to the periodic structure of the bodies in space
(the crystal) and in time (the oscillators) via
the three corresponding quantum rules for the
momentum and energy activity of the periodic bodies.
He calls his particle interpretation
"practical realism", and offers
reinterpretations of Heisenberg's and Schrödinger's
equations.
The Heisenberg uncertainty relations describe
objective statistical dispersion.
Heisenberg's claim, that simultaneous exact
position and momentum measurement pairs is
meaningless and nonexistent, is incorrect because it
confuses lack of predictability (which is true) with
lack of measurability (which is false).
Unpredictable data including position and
momentum measurement pairs can be reconstructed
which are more accurate than Planck's constant.
And what can be measured, exists.
The doctrine of the indeterminacy of
existence is a "semantic artifice" rather
than legitimate physics.
Nor is denying that a particle always is
somewhere, warranted by diffraction experiments,
because each particle reacts to a space-extended
periodic component in the matter distribution of the
diffractor.
To say that the particle is nowhere is a
"linguistic extravaganza" and not a
philosophical innovation.

As for Schrödinger's equation, Lande says
that it does not deal with matter waves, but with
probability amplitudes; it is a probability table
not essentially different from any mortality table.
The real constituents of matter are discrete
particles, which occasionally give the appearance
of wave action, and the real constituent of light is
a continuous electromagnetic field, which
sometimes gives the appearance of photonic
particles.
The Schrödinger wave function is a probability
curve describing betting odds for future events; it
is not a real thing even when the curve looks
wave-like.
Lande uses the phraseology of Dr. Samuel
Johnson (a critic of Bishop Berkeley's *esse
est percipi* philosophy, who kicked a great stone
and exclaimed "I refute him thus") saying
that you can kick a stone, and you can kick an
electron and even a water wave and an
electromagnetic wave, and be hurt by them, thus
proving their reality.
But you cannot kick or be hurt by a wave-like
curve representing probabilities of events.
For Lande, physical interaction is the only
correct ontological criterion for physical reality.
He also takes exception to Born, his former
colleague, who had initially developed the
statistical interpretation of the Schrödinger wave
function as a probability amplitude for particles,
but who later made what Lande calls "belated
concessions" to the Copenhagen dualistic
interpretation.
He references Born's "Physical
Reality" appearing in *Philosophical
Quarterly* (1953) in which Born sets forth his
own ontological criterion, the criterion of
invariance.
In this article Born is not explicitly
opposing Lande, but rather is opposing the Idealist
metaphysics and the Logical Positivist philosophy of
phenomenalism.

Born explains his criterion of invariance as
follows: Most measurements in physics are not
concerned with things that interest us, but are
concerned with some kind of projection which is
defined in relation to a system of reference.
In every physical theory there is a rule
which connects the projections of the same object on
different reference systems.
The rule is called a law of transformation,
and all transformations have the property of forming
a "group", where the sequence of two
consecutive transformations is a transformation of
the same kind.
Invariants are quantities having the same
value for any system of reference, and therefore are
independent of the transformations.
The main advances in the conceptual structure
of physics consist in the discovery that some
quantity which was formerly regarded as the property
of a thing, is in fact only the property of a
projection.
The historical development of the theory of
gravitation from pre-Newtonian physics to relativity
theory is one example.
Another example is the development of quantum
physics.
An observation or measurement in quantum
physics does not refer to a natural phenomenon as
such, but to its projection on a system of reference
which is the whole apparatus used in the experiment.
Using instruments the physicist can obtain
certain restricted but well described information,
which is independent of the observer and of his
apparatus, namely the invariant features of a
number of properly devised experiments. Bohr's
complementarity principle means that the maximum
knowledge of the quantum can only be obtained by a
sufficient number of independent projections of
the same physical entity.
The final result of complementary experiments
is a set of invariants characteristic of the entity,
and these invariants are called "charge",
"rest mass", "spin", etc.
In every instance, when we are able to
determine these quantities, we decide we are
dealing with a definite particle.
The words "photon",
"electron", etc. signify definite invariants,
that can be constructed by combining a number of
observations.

Born maintains that the idea of invariance is
the clue to a rational concept of reality, not only
in physics but also in every aspect of the world.
The power of the mind to neglect the
differences of sense impressions and to be aware
only of their invariant features is the most
impressive fact of man's mental structure.
He proposes translating the term "*gestalt*"
not as "shape" or "form" but as
"invariant.”
And he proposes speaking of invariants of
perception instead of sense impressions as the
elements of our mental world.
In the closing paragraph of his article Born
considers the reality of waves according to his
ontological criterion of invariance.
He says that we regard waves on a lake as
real, though they are nothing material but are only
a certain shape of the surface of the water.
The justification for this view is that they
can be characterized by certain invariant quantities
like frequency and wavelength, or as a spectrum of
these.
Born says that the same thing holds for light
waves, and he asks rhetorically why the physicist
should withhold the epithet "real" even if
the waves represent in quantum theory only a
distribution of probability.

In his *New Foundations* Lande replies to Born's rhetorical question from the
viewpoint of his own criterion of interaction:
Particles are real while Schrödinger waves are not
real, for the same reason that sick people are real
things while the wave-like curve which symbolizes
the probability distribution during a fluctuating
epidemic is not a real thing.
Lande says that a given formalism can always
be interpreted in a variety of ways.
At the conclusion of his *New
Foundations* he gives seven alternative
interpretations of the Schrödinger wave function
including Schrödinger's, de Broglie's, Bohm's,
Heisenberg's subjective interpretation,
Heisenberg's objective interpretation together with
Bohr's instrumentalist interpretation, and Lande's
own interpretation.
He does not include Popper's propensity
interpretation.
He states that this list is indicative of the
present confusion regarding the wave function, and
paraphrases Mao Tse Tung saying that while it may be
good politics to let a hundred flowers bloom and let
a hundred schools contend, it is not good enough for
science.
He asserts that only his interpretation
stands up to realistic criticism in accordance with
"monolithic" quantum mechanics, i.e.
quantum theory with an ontology that is consistent
with the rest of physics.

**Popper's
Particle-Propensity Interpretation of Quantum Theory
**

Popper explains the basis for the schism in
physics as follows: On the one hand Einstein was a
determinist, who believed that the statistical
nature of quantum theory is due to the physicist's
ignorance of the underlying deterministic laws,
which have not yet been discovered.
Therefore Einstein chose a subjective
interpretation of probability based on the
scientist's ignorance.
On the other hand Heisenberg was an
indeterminist, but because the only objective
interpretation of probability available at the time
was the frequency interpretation, Heisenberg's
introduction of the observer's disturbance of the
quantum phenomenon by the measurement apparatus
resulted in the combination of both the objective
and subjective interpretations of the probability
function in the Copenhagen interpretation of the
quantum theory.
The frequency interpretation is applicable
only to mass phenomena, while the quantum theory
pertains to singular events.
Therefore in order to describe the single
quantum event, it seemed necessary to view
probability as describing the scientist's ignorance
resulting from the disturbance.
For this reason according to Popper the
Copenhagen interpretation also relies on the
subjective interpretation of probability.
Popper's propensity hypothesis advances an
objective interpretation of the probability calculus
and of probabilistic theories in physics, and it is
an objective interpretation that is applicable to
singular events.
Popper has arguments for probability
interpretations that are exclusively objective,
but any objective interpretation requires a
realistic philosophy with an indeterministic
ontology.
Therefore he also advances arguments for
realism and indeterminacy, as well as for
objectivism.

Popper has several arguments against the
subjective interpretation of probability and for
the objective interpretation.
Some quantum theorists such as Pauli
introduce the idea of induction into discussions
about the statistical nature of quantum theory.
Popper rejects this application of
inductivism for the same reasons that he rejects all
applications of the idea of induction; induction is
psychologistic and confuses world 2 with world 3.
He also argues that the idea of explaining
the statistical outcomes of experiments and
predictions in terms of the ignorance of the
physicist is absurd.
Empirical science absolutely never explains
anything in terms of the researcher's ignorance; it
always explains phenomena in terms of other
phenomena.
While this argument of Popper’s is true and
may apply to some subjective interpretations of the
quantum theory, it does not apply to interpretations
such as Heisenberg’s, which invoke the subjective
interpretation of probability only to address the
problem of measurement errors, thus giving the
subjective interpretation a metalanguage status
instead of the object-language status of an
explanation in physics.

Popper's argument for realism is based on his
falsificationist thesis of scientific criticism.
Simply stated, he argues that the possibility
of falsification is evidence of the existence of the
real world that is independent of human knowledge.
He furthermore argues that the fact that theories
are conjectures does not imply that they do not describe
the real world.
Rational criticism results in better theories
that have greater verisimilitude.
Popper argues against instrumentalism, which
he associates with both Bohr and Heisenberg.
In "Three Views Concerning Human
Understanding" in *Conjectures
and Refutations* he references Heisenberg's
thesis that physical theories such as Newton's are
not falsified, but rather have had their
applicability restricted by later theories such as
relativity and quantum mechanics.
This view is an aspect of Heisenberg's
doctrine of closed-off theories, although Heisenberg
did not set forth his doctrine of closed-off
theories as an instrumentalist thesis.
In a footnote in this paper Popper states
that Heisenberg's instrumentalism is far from
consistent, and that he has many
anti-instrumentalist remarks to his credit, but that
Heisenberg's view of quantum theory necessarily
leads to an instrumentalist philosophy by neglecting
falsification and stressing application.
A mere instrument cannot be falsified, and
the instrumentalist view may be used *ad
hoc* to rescue a theory threatened by
falsifications.
Popper maintains that such an evasion was
the reason that Bohr advanced his principle of
complementarity, the renunciation of the attempt to
interpret atomic theory as a description of
anything; the self-consistent formalism need not be
reconciled with its inconsistent applications, if it
is left uninterpreted.
On Popper's view the unfalsifiability thesis
of the instrumentalist view makes instrumentalism
incapable of explaining scientific criticism and
scientific progress.
Only by reaching for refutations can science
hope to learn and to advance.

Popper argues against determinism, and in
this respect he takes exception to Einstein,
although he says that he may have changed Einstein's
mind about determinism in a conversation at
Princeton in 1950.
Popper distinguishes between metaphysical
determinism, which is a thesis about the whole
world, and scientific determinism, which is a thesis
about the part of the world described by a
scientific theory.
He classifies Einstein as a metaphysical
determinist, and reports that in his discussions
with Einstein he referred to him by the name
Parmenidies, because like the ancient philosopher
Parmenidies, Einstein's metaphysical determinism
implies that the future is entirely contained in the
past, and that change is not real but is merely an
appearance.
Popper also argues against scientific
determinism, and specifically he denies that
Newtonian mechanics implies a deterministic
ontology.
He describes the theories of classical
physics as *prima
facie* deterministic, by which he means that the
deterministic character is a property of the theory
and not of the real world.
He maintains that classical physics does
not imply determinism any more than quantum
physics does, because there is always an irreducible
and stable statistical element in any predictions
made with a *prima
facie* deterministic theory; and it is always
necessary to add to the deterministic theory a
probability assumption to explain the statistical
component in the prediction, because statistical
conclusions require statistical premises.
Popper quotes at length Lande's description
of the experiment with the ivory balls and steel
blade, which Lande uses to argue that statistical
results require statistical assumptions about the
initial conditions.
Therefore Popper rejects attempts to explain
the statistical outcomes subjectively by reference
to lack of knowledge of the experimenter for the
reasons given above, and he maintains that the
law-like behavior of statistical sequences is for
the determinist ultimately inexplicable.

Popper developed his propensity
interpretation of probability in 1950 specifically
to address the interpretation problem arising from
statistical quantum theory, but it is also intended
to be applicable to all physics.
While it is but one of many interpretations
for the probability calculus, it is the best for
physics in Popper's view.
Popper distinguishes three objective
interpretations of the probability calculus: the
classical interpretation, the frequency
interpretation, and his propensity interpretation.
The classical interpretation is that the
probability measure P(a,ß) is the proportion of
equally possible cases compatible with the event
ß, that are also favorable to the event a.
The frequency interpretation is that P(a,ß)
is the relative frequency of the events a among the
events ß.
The propensity interpretation is a refinement
of the classical interpretation.
In the classical interpretation experimentation
is not needed, because it deals with equally
possible cases, such as the two sides of a coin or
the six faces of a die.

The propensity interpretation substitutes
weights for equally possible cases, where the
weights are experimentally determined measures of
the propensity or tendency of a possibility to
realize itself upon repetition.
Thus in the propensity interpretation the
measure P(a,ß) is the propensity of a given
experimental conditions ß.
It is the sum of the weights of the possible
cases that satisfy the condition ß which are also
favorable to a, divided by the sum of the weights of
the possible cases that satisfy ß.
The propensity interpretation is closely
related to the frequency interpretation; the latter
is about frequencies in actual finite sequences of
experiments, while the former is about virtual
finite sequences.
In the propensity interpretation probability
statements are about some measure of a physical
property of the whole repeatable experimental
arrangement, a measure of a virtual frequency, and
the probability distribution is taken to be a
property of the single experiment.
The fact that the probability distribution in
the propensity interpretation is a property of a
single experiment is the strategic characteristic of
this interpretation for quantum theory.
Previously in *Logic
of Scientific Discovery* Popper had attempted to
modify the frequency interpretation so that it could
address single events by means of what he called
"formally singular statements.”
He abandoned this idea, when he developed the
propensity interpretation.
Now he says that the frequency measurements
function to test the conjectured virtual frequency,
which is a conjecture like any other scientific
hypothesis.

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**NOTE: Pages do not corresponds
with the actual pages from the book**