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Hanson further follows Wittgenstein when he
maintains that the meaning of a sentence is its use,
and that there are multiple uses for a sentence.
Thus he states that the laws and theories of
physics have many uses, and not just one, as most
philosophers have maintained.
The contingently empirical status of a
statement is one of the uses of the theory in
science. Another
is to make the phenomena cohere in an intelligible
way, such that empirical disconfirmation does not
result in the negation of the concept described by
the theory, but rather results in no coherent
concept at all.
The dynamical laws of classical physics, for
example, are a system of propositions that are
empirically true, and the fundamental propositions
on which the system rests are empirically true.
But these fundamental propositions are also
treated as axioms, such that the system delimits and
defines its subject matter.
Then nothing describable within the system
could refute its law statements; disconfirmatory
evidence counts against the system as a whole, and
only shows that the system does not hold, where
formerly it was thought to hold.
Hanson calls this use of laws and theories
functionally a
priori. These ideas are reminiscent of Heisenberg's comments in
"Questions of Principle in Modern
Physics", in which he says that it is not the
validity but only the applicability of classical
laws, which is restricted by modern relativity and
quantum physics. Hanson does not reference Heisenberg, but his thesis of the
functionally a
priori use of laws and theories is in this
respect similar to Heisenberg's doctrine of a
closed-off theories, with the noteworthy exception
that Hanson does not reserve certain axiomatic
systems such as classical mechanics for observation
in physics, as does Heisenberg in his explicit
philosophy of physics.
Heisenberg's philosophy of observation in his
doctrine of closed-off theories does not admit the
variability in perception that Hanson's philosophy
asserts. Instead
in his explicit philosophy Heisenberg followed
Bohr's thesis that there are forms of perception
that are found only in colloquial language and in
its refinements in classical physics.
Hanson's semantical investigations sometimes
took a turn away from the wholistic approach of
Gestalt psychology.
In the chapter on classical particle physics
in Patterns of
Discovery he considers the idea that the
meanings of some names have their properties built
into them, such that falsification of statements
predicating those properties of the named substances
is effectively impossible.
And in "Newton's First Law: A
Philosopher's Door into Natural Philosophy"
in Beyond the Edge of Certainty (1965), he states that rectilinearity,
motion ad
infinitum, and free force, are conceptions
within classical mechanics that are interdependent,
in such a way that it is possible to treat the idea
of uniform, rectilinear motion ad
infinitum as itself built into the notion of
free force, as part of the latter's semantical
content. The
terms in Newton's first law are semantically linked:
the meaning of some of its component terms unpacks
sometimes from one or two of the others, but then
sometimes the meaning of these unpacks from that of
the first. Which
are the contained and which are the semantical
containers can affect the logical exposition of any
mechanical theory built thereon.
These are semantical decisions which
guarantee that in different formalizations of
Newton's theory different meaning relations will
hold between the law's constituent terms.
The term “unpack” in connection with
semantical analysis is a phrase used by the early
Pragmatist philosopher William James, although
Hanson does not reference James.
It is unclear whether or not Hanson ever
thought of this type of semantical analysis as an
alternative to his frequent recourse to Gestalt
psychology. Nevertheless
it is an alternative approach in semantical
analysis, because it is not wholistic.
On the
gestalt thesis it is not possible to unpack a gestalt
into its component parts, because the gestalt
is more than a mechanical organization of its parts.
In his discussions of quantum theory Hanson
never exploited this mechanistic or logical analysis
of meanings into component parts.
Hanson's
Philosophy of Science
Aim of Science and Discovery
Hanson's ideas about the aim of science
pertain to what he calls research science, as
opposed to what he calls almanac science, and are
integral to ideas of scientific discovery.
In his "Introduction" in Patterns
of Discovery he states that in a growing
research discipline, inquiry is directed not to
rearranging old facts and explanations into more
elegant formal patterns, but rather to the discovery
of new patterns of explanation.
The idea that observation is theory-laden is
strategic to this purpose.
In the chapter titled "Observation"
in Patterns of
Discovery he states that the scientist aims to
get his observations to cohere against a background
of established knowledge.
This kind of seeing is the goal of
observation. And
similarly in the last chapter titled
"Elementary Particle Physics", the area of
contemporary physics that he says is presently a
research science, he states that intelligibility is
the goal of physics, the conceptual struggle to fit
each new observation of phenomena into a pattern of
explanation. Often
the pattern precedes recognition of the phenomena,
as Dirac's theory of 1928 preceded discovery of the
positron, the antiproton, and the antineutron.
But then Dirac's pattern was itself the
outcome of an effort to find a suitable explanation
for prior phenomena, namely a unified,
relativistically invariant theory of electron spin,
which would give the correct fine structure formula,
explain the Zeeman effect of the doublet atoms,
describe the Compton scattering, and supply a model
of the hydrogen atom.
Explanation
Hanson offers an evolutionary perspective on
scientific explanation.
In the third chapter of Concept
of the Positron he states that the concept of
scientific explanation has experienced a historical
evolution that follows upon the historical
development of physics.
Leibniz denied that Newton's theory offers
explanation, even though he admitted that it offers
acceptable predictions.
Today the concept of explanation advanced by
the Positivists, such as Hempel, is based on the
concepts of Newton's physics including notably the
deterministic thesis that explanation implies
deterministic prediction. The concept of explanation implied in the nondeterministic
quantum theory is not yet accepted.
Hanson states that if just after Leverrier
had predicted the existence of the planet Neptune in
1847, a time when Newtonian physics had reached its
apex, some physicist who had proposed a new theory
that explained all that Newton's theory explained
and furthermore explained several minor flaws in
Newton's theory, the new and better theory would
have been viewed as merely a predictive device, not
an explanation. But if Newton's theory then began to
show major weaknesses, while the new theory
succeeded where Newton's had failed, still these
accomplishments would decide nothing.
The scientists would begin to show increasing
reliance on the new theory, yet it would not be
accepted as an explanation.
All the same, younger physicists would
develop the new theory further. Finally if Newton's physics had begun to fall apart while the
new theory opened up new branches of science,
focused on problems never before perceived, fused
disciplines previously thought to be distinct, and
sharpened experimental techniques to an
unprecedented degree, then the very pattern of
thinking in an inquiry properly called scientific
would reflect the new physics with its new concept
of scientific explanation; to be able to cope with a
scientific problem at all, would be to have become
able to build it into the conceptual framework of
the new physics.
Hanson distinguishes three stages in this
process of the evolution of a new concept of
explanation; they are the black box, the gray-box,
and the glass box.
In the first stage, the stage of the black
box, there is an algorithmic novelty, a new
formalism, which is able to account for all the
phenomena that an existing formalism can account
for. Scientists
use this technique, but they then attempt to
translate its results into the more familiar terms
of the orthodoxy, in order to provide understanding.
In the second stage, the stage of the gray
box, the new formalism makes superior predictions in
comparison to the older alternative, but it is still
viewed as offering no understanding.
Nonetheless it is suspected as having some
structure that is in common with the reality it
predicts. In
the third stage, the stage of the glass box, the
success of the new theory will have so permeated the
operation and techniques of the body of the science
that its structure will also appear as the proper
pattern of scientific inquiry.
Hanson says that quantum theory is in the
second stage, because scientists have not yet ceased
to distinguish between the theory's structure and
that of the phenomena themselves.
This evolution is the gradual adoption of the
practice of scientific realism, in which (to mix
metaphors) the glass becomes the spectacles through
which reality is seen. Explanatory langauge is customarily thought to be
explanatory, because it describes the real causes of
the phenomena explained. Therefore, the concept of
causality also undergoes the kind of evolution that
occurs with the concept of explanation.
In the chapter titled "Causality"
in Patterns of
Discovery Hanson says that cause words are
theory-laden; they are the details in an intricate
pattern of concepts.
Causes are connected with effects, but only
because theories connect them, not because the
universe is held together with a cosmic glue.
Questions about the nature of causation are
to a large degree questions about how certain
descriptive terms in definite contexts coupled
together complement and interlock in a pattern of
other terms. The
elements of explanation, causation, and theorizing
become worked into a comprehensive language pattern.
Criticism
Hanson's discussion of scientific criticism
is principally concerned with the topic of crucial
experiments. He
takes up the topic in a chapter in Concept
of the Positron in which he discusses the
different concepts of light in the history of
physics, and he discusses it again later in a
special chapter in Perception and Discovery. Hanson's
rejection of the idea of crucial experiments has its
basis in his thesis that observation is
theory-laden. A
commonly referenced example of a crucial experiment
is Foucault's 1850 crucial test between the wave and
particle concepts of light.
In that experiment Foucault demonstrated that
light travels more rapidly in air than in water. According to the doctrine of the crucial experiment the
corpuscular hypothesis should have been banished
forever. But
this has not happened.
The photoelectric effect and the Compton
effect can only be explained on a corpuscular theory
of the nature of light.
The experiments are not crucial, because the
observations are important only against the
assumptions, theories, and hypotheses that are in
the balance before the experiment is performed.
One of the assumptions is that light cannot
be both wave and particle.
The crucial test is a test of the alternative
hypotheses together with all of their assumptions,
just as in ordinary scientific observation there is
a pure registration or sensation plus all of the
assumptions necessary to give those sensations
meaning. If
we were forced to revise our assumptions, then the
crucial experiment must be re-interpreted, so that
it need not decide against one of the hypotheses.
Some of the most profound revolutions in
modern science have consisted not in the criticisms
of old hypotheses, but in the criticism of the
assumptions underlying the hypotheses.
Crucial experiments are crucial against some
hypothesis only in relation to a stable set of
assumptions that we do not wish to abandon.
But no set of assumptions is permanently
valid. Hanson
says that crucial experiments are out of the same
bag as pure observations and uninterpreted facts;
they are philosophers' myths.
Wittgenstein said language has many uses.
Hanson's discussions of crucial experiments
pertain only to theories that may intelligently be
disconfirmed. Although
in principle all statements of science are testable
and can be falsified, in practice theories often
have another use or function.
Following Wittgenstein's thesis that language
may have many uses, Hanson maintains that theories
functioning as pattern statements supplying a
conceptual gestalt
will not yield an intelligible statement negating
the theory, if the theory is viewed as disconfirmed.
This is because the theory gives the
phenomena their intelligibility; and this explains
why scientist will not reject a theory even while
they recognize the existence of anomalies that are
not intelligible in the theory. What scientists do in practice is to attempt to save the
theory with small modifications or wait until a new
and more adequate theory is proposed that explains
all that the old theory explains as well as the
anomalies to the old theory.
Anomalies do not make scientists give up
intelligibility. It is for this reason that physicists have not given up the
Copenhagen interpretation in spite of the anomalies
confronting Dirac's theory.
Thus Hanson, opposing Bohm in the
"Postscript" chapter in Quanta
and Reality, states that dropping orthodox
quantum theory right now would be to stop doing
microphysics altogether.
Then Hanson immediately adds that should the
heretics (Bohm et
al.) succeed in accounting for everything that
orthodox theory now describes, and do so without the
divergence difficulties and the renormalization
nuisance even without the uncertainty relations and
the irreducibly statistical laws, should they do all
this, then physicists of the world will be at their
feet, and science will have ascended to a new plane
of power and fertility.
Hesse
on Models and Analogy
Quanta
and Reality (1962) is a collection of discourses
initially broadcast as a radio series by the BBC in
1961. It
includes a dialogue involving Bohm, a
"Postscript" commentary by Hanson, and a
commentary titled "Models and Matter" by
the Cambridge University philosopher of science,
Mary B. Hesse. Hanson's comments are generally critical of Bohm; Hesse’s
are more sympathetic. This
alignment among the participants is not limited to
the specifics about the contemporary quantum theory;
it divides along issues about the semantics of
scientific theories in general and also about the
role of semantics in scientific discovery.
All participants have much to say about the
semantics involved in scientific discovery.
On Hanson's view the semantics of a theory is
determined completely by the mathematical formalism
and the measurements that the equations of the
formalism relate.
The relations expressed by the theory
including its grammatical/mathematical form
determine the conceptual gestalt,
which constitutes the semantics of the theory.
And in the case of quantum theory the
Copenhagen semantical interpretation with its
wave-particle duality thesis is integral to the
mathematical formalism of the quantum theory.
Furthermore the semantics of the quantum
theory so understood is strategic to the further
development of microphysics, as evidenced by the
fact that Dirac said he relied on it for his
development of his field quantum theory.
Hanson does not deny that there may also be
other language about the microphysical domain
explained by the equations of the quantum theory,
language that does not contradict the quantum
theory. But
he views such supplementary language as mere
philosophy, and not as part of the theory itself.
He places Bohr's naive epistemology in this
category of supplementary philosophical language.
Opponents to the Copenhagen interpretation
agree with Hanson that semantics has a strategic
role in scientific discovery.
But they do not agree that the Copenhagen
interpretation is integral to the formalism of the
theory. They
are motivated to disagree not only because some of
them propose alternatives to the wave-particle
duality thesis, but also because in general they
maintain that there is more that determines the
semantics of theories than just the formalism and
measurement concepts.
The source of this additional semantics that
they say is found in many if not all theories, is
the nonliteral figurative and often imaginative
language, which they find historically
characteristic of theories in physics.
This figurative language involves analogies
and metaphors, and the distinctively additional
semantics is often called a model.
This is one of several common meanings for
the term model, and in the present context the term
functions to articulate the different views on the
issue at hand.
Unlike Hanson, Hesse views the ideas of waves
and particles as theoretical models for quantum
theory, and her view proceeds from a sophisticated
examination of these questions.
Hesse's views about the semantics of theories
are influenced by her former mentor at Cambridge, R.
B. Braithwaite, a Logical Positivist philosopher of
science. Their
views are similar but not the same. Both Hesse and Braithwaite are Positivists, and thus
distinguish observation and theoretical terms,
although Hesse’s views evolved beyond Positivism
later in her career.
The distinction between observation and
theoretical terms produces for Positivists the
peculiar problem as to how theoretical terms
contained in a semantically uninterpreted formal
calculus can be meaningful instead of meaningless or
metaphysical. In
his Scientific
Explanation (1953) Braithwaite distinguishes two
sources of semantical interpretation for an
uninterpreted formal calculus containing theoretical
terms: Firstly the formal calculus may receive its
semantical interpretation that makes it a meaningful
scientific theory containing theoretical terms, when
the logically posterior statements of implied
consequences, the observation sentences, determine
the meaning of the theoretical terms in the calculus
of the logically prior premises.
Theoretical terms are thus said to receive
indirect meaning, since their meanings are
determined by their contexts in relation to one
another and to the sentences expressing the
observable directly testable outcomes, which the
experimentalist can logically derive from them.
In other words the meanings of the
theoretical terms are indirect, because they receive
all their semantics contextually and not ostensively,
as do observation terms.
Braithwaite labeled this view contextualism.
Yet Braithwaite also maintains that a good theory is
capable of growth, such that it must be an
alternative way of describing the empirical
statements upon which it is based.
Therefore he admits that the meanings of the
theoretical terms need not be limited to being
contextually defined explicitly, because the
indirect contextual interpretation does not satisfy
this growth criterion for theories.
Then Braithwaite states secondly that a
theory may furthermore be given an interpretation by
another source called a model.
A model is additional language that
contributes meaning to the terms, both those
occurring in the premises and those in the
conclusions, both to the theoretical terms and the
observation terms.
Most notably, unlike the contextual
definition the model is not a literal
interpretation for the domain explained by the
theory. Thus
Braithwaite says that theories and models have
different epistemological structures, even when they
have the same calculus.
It might also be said that the introduction
of the model makes the theoretical terms equivocal
with one meaning the literal one defined in context
and another the nonliteral one defined by the model
language. For
example according to Braithwaite the solar system
may serve as a model for the hydrogen atom, even
though it is understood that the atom is not
literally to be taken as a solar system.
Braithwaite says that thinking of theories by
means of models is always "as-if"
thinking, e.g. thinking of the atom as if it were a
solar system. But
he makes an exception for quantum theory: he says
that for the physicist, Schrödinger's wave function
is exhaustively interpreted in terms of its use in
the calculus of the quantum theory, and he states in
a footnote that no one supposes that the wave
function denotes a wave in any ordinary sense of
wave. In Braithwaite's view modern quantum theory
does not have any model.
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