C.T.R. Wilson – and to misconceive the electron as simultaneously having a definite position and momentum like all Newtonian bodies in motion.
Recalling Einstein’s aphorism that the theory decides what the physicist can observe, Heisenberg reconsidered what is observed in the cloud chamber. Einstein had failed to apply his aphorism to quantum theory, and rejected duality. But Heisenberg rephrased his question about the electron tracks in the cloud chamber using the concepts of the new quantum theory instead of those of the classical Newtonian theory. He reports that he asked himself: Can the quantum mechanics represent the fact that an electron finds itself approximately in a given place and that it moves approximately at a given momentum? In answer to this newly formulated question he found that these approximations could be represented mathematically. He then developed this mathematical representation, which he called the “uncertainty relations”, the historic contribution for which he received the Nobel Prize in 1932.
Russell Hanson expressed Einstein’s aphorism that the physical theory decides what the physicist can observe by saying observation is “theory-laden” and likewise Karl Popper by saying it is “theory-impregnated”.
Paul Feyerabend also recognized employment of relativized semantics to create new observation language for discovery, and he called the practice “counterinduction”. Feyerabend found that Galileo had practiced counterinduction in the Dialogue Concerning the Two Chief World Systems (1632), where Galileo reinterpreted apparently falsifying observations in common experience by using the concepts of the heliocentric theory instead of the concepts of the geocentric theory. Likewise Heisenberg also practiced counterinduction to reconceptualize the perceived sense stimuli observed as the electron track in the cloud chamber by using quantum concepts instead of classical Newtonian concepts.
“Counterinduction” is using the semantics of an apparently falsified theory to revise the test-design language that had supplied the semantics of the descriptive language for the falsifying observations, and thereby to produce new observation language.
Like Einstein, contemporary pragmatists say that the theory decides what the scientist can observe. Thus semantics is relativized in the sense that the meanings of descriptive terms used for reporting observations are not just names or labels for phenomena, but rather are determined by the context in which they occur. More specifically in “Five Milestones of Empiricism” in his Theories and Things the pragmatist philosopher of language Willard van Quine says that the meanings of words are abstractions from the truth conditions of the sentences that contain them, and that it was this recognition of the semantic primacy of sentences that give us contextual definition.
Most notably the defining context includes universal statements that proponents believe are true. The significance is that the acceptance of a new theory superseding an earlier one and sharing some of the same descriptive terms produces a semantical change in the descriptive terms shared by the theories and by their observation reports.
Thus Einstein for example changed the meanings of such terms as “space” and “time”, which occur in both the Newtonian and relativity theories. And Heisenberg changed the meanings of the terms “wave” and “particle”. Feyerabend calls the semantical change due to the relative nature of semantics, “meaning variance”.
Thesis II: Empirical underdetermination.
Empirical underdetermination refers to the limited ability of the semantics of language at any given time to signify reality.
Measurement error and conceptual vagueness, which can be reduced indefinitely but never completely, eliminated, exemplify the omnipresent and ever-present empirical underdetermination of language that produces observational ambiguity and theoretical pluralism. Einstein recognized that a plurality of alternative but empirically adequate theories could be consistent with the same observational description, a situation that in his autobiography he called “an embarrassment of riches”.
Additional context including law statements in improved test-design language contributes additional semantics to the observational description in the test designs, thus reducing while never completely eliminating empirical underdetermination. In his Word and Object Quine introduced the phrase “empirical underdetermination”, and wrote that the positivists’ theoretical terms are merely more empirically underdetermined than terms they called observation terms. Thus the types of terms are not qualitatively different.
Thesis III: Ontological relativity.
In his discussions about Einstein’s special theory of relativity in Physics and Philosophy and in Across the Frontiers Heisenberg describes the “decisive step” in the development of special relativity. That step was Einstein’s rejection of 1902 Nobel-laureate Hendrik Lorentz’s distinction between “apparent time” and “actual time” in the Lorentz-Fitzgerald contraction. Lorentz took the Newtonian concepts to describe real space and time. In his relativity theory Einstein took Lorentz’s “apparent time” as physically real time, while altogether rejecting the Newtonian concept of absolute time as real time. In other words the “decisive step” in Einstein’s special theory of relativity consisted of Einstein’s taking the relativity theory realistically, thus letting his relativity theory characterize the physically real, i.e., physical ontology.
Also in “History of Quantum Theory” in his Physics and Philosophy Heisenberg describes his imitation of Einstein in his discovery experience for quantum theory. There he states that his thinking about the uncertainty relations consisted of turning around a question. Instead of asking himself how one can express in the Newtonian mathematical scheme a given experimental situation, he asked whether only such experimental situations can arise in nature as can be described in the formalism of his quantum mechanics. The new question is an ontological question with the answer supplied by his quantum theory.
Again in “Remarks on the Origin of the Relations of Uncertainty” in The Uncertainty Principle and Foundations of Quantum Mechanics Heisenberg explicitly states that a Newtonian path of the electron in the cloud chamber does not exist. And still again in “The Development of the Interpretation of the Quantum Theory” in 1945 Nobel-laureate Wolfgang Pauli’s Niels Bohr and the Development of Physics, Heisenberg says that he inverted the question of how to pass from an experimentally given situation to its mathematical representation. There he concludes that only those states that can be represented as vectors in Hilbert space can exist in nature and be realized experimentally. And he immediately adds that this conclusion has its prototype in Einstein’s special theory of relativity, when Einstein had removed the difficulties of electrodynamics by saying that the apparent time of the Lorentz transformation is real time.
Like Heisenberg in 1926, the contemporary pragmatist philosophers let the scientist rather than the philosopher decide ontological questions. And the scientist decides on the basis of empirical adequacy demonstrated in his empirically tested explanations. Many years later in his Ontological Relativity Quine called this thesis “ontological relativity”, as it is known today.
Ontological relativity did not begin with Heisenberg much less with Quine. Copernicus and Galileo practiced it when they both interpreted heliocentrism realistically thus accepting the ontology it describes – to the fateful chagrin of Pope Urban VIII. Heisenberg’s Copenhagen interpretation still prevails in physics today. But should future superior test designs and experiments result in falsification of his Copenhagen interpretation, then physicists’ practice of ontological relativity would make a newer empirically more adequate theory define the prevailing ontology in future microphysics.
The contemporary pragmatist concepts of the four functional topics are summarized as follows:
Aim of science:
The
