Preludes to ontic structural realism : Eddington and Weyl : a theoretic route from general relativity to quantum mechanics through group theory (original) (raw)
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In search of (spacetime) structuralism
Philosophical Perspectives, 2011
The debate between substantivalists and relationists about spacetime was given a new lease of life twenty years ago, when John Earman and John Norton published an argument for the conclusion that, in the light of general relativity, substantivalism is untenable. Responses to Earman and Norton's argument generated a proliferation of 'substantivalisms', and a debate between them that was, to the ears of at least some, distinctively metaphysical in character.
Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics, 2017
This paper aims at closing a gap in recent Weyl research by investigating the role played by Leibniz for the development and consolidation of Weyl's notion of theoretical (symbolic) construction. For Weyl, just as for Leibniz, mathematics was not simply an accompanying tool when doing physicsdfor him it meant the ability to engage in well-guided speculations about a general framework of reality and experience. The paper first introduces some of the background of Weyl's notion of theoretical construction and then discusses particular Leibnizian inheritances in Weyl's 'Philosophie der Mathematik und Naturwissenschaft', such as the general appreciation of the principles of sufficient reason and of continuity. Afterwards the paper focuses on three themes: first, Leibniz's primary quality phenomenalism, which according to Weyl marked the decisive step in realizing that physical qualities are never apprehended directly; second, the conceptual relation between continuity and freedom; and third, Leibniz's notion of 'expression', which allows for a certain type of (surrogative) reasoning by structural analogy and which gave rise to Weyl's optimism regarding the scope of theoretical construction.
In the last times some scholars tried to characterize Einsteins distinction between constructive i.e. deductive - theories and principle theories, the latter ones being preferred by Einstein. Here this distinction is qualified by an accurate inspection on past physical theories. Some previous theories are surely non-deductive theories. By a mutual comparison of them a set of features - mainly the arguing according to non-classical logic - are extracted. They manifest a new ideal model of organising a theory. Einsteins paper of 1905 on quanta, qualified by him as a principle theory, is interpreted according to this model of theory. Some unprecedented characteristic features are manifested. At the beginning of the same paper Einstein declared one more dichotomy about the kind of mathematics in theoretical physics. These two dichotomies are recognised as representing the foundations of theoretical physics. With respect to these dichotomies the choices by Einstein in the paper on quanta are the alternative choices to Newtons ones. This fact gives reason to the revolutionary nature that Einstein attributed to his paper. Keywords: Quanta, Einstein, principle theory, kinds of organization, kinds of mathematics
Between Physics and Metaphysics: Structure as a Boundary Concept
The notion of structure is found to be used in a great number of theories, scientific research programs and world views. However, its uses and definitions are as diverse as the objects of the scientific disciplines where it can be found. Without trying to recreate the structuralist aspiration from the mid XX century, which believed to have found in this notion a common transdisciplinary language, I discuss a specific aspect of this concept that could be considered a constant in different perspectives. This aspect refers to the location of the notions of structure as boundaries in the different scientific theories. With this, I try to argue that the definition or presentation of a structure configures in itself the frontier for scientific knowledge, defining at the same time implied ontological assumptions. In order to discuss this hypothesis, and taking into consideration the double origin of contemporary notions of structure –the mathematical and linguistic line–, I revise several theoretical perspectives which made explicit the relation between structures and knowledge, and their relation with the real: the arguments on physical knowledge by Eddington, structural anthropology, structural linguistics, Lacanian psychoanalysis and Piaget’s genetic psychology.
On the basis of an analysis of everyday experience and practice, criteria of legitimate assertions of existence and truth are offered. A specific object, like a newspaper, can be asserted to exist if it has some invariant characteristics and is present in actual perception. A statement, like «This newspaper is black and white», can be accepted as true if it is wellestablished in some empirical domain. Each of these criteria provides a sufficient condition for acceptance of existence and truth, respectively, at the empirical level. Following Herman Weyl, it is argued that these criteria can be extended to the scientific theoretical level to support a selective and moderate version of scientific realism according to which entities like the electromagnetic and gravitational fields, but not crystalline spheres or some topological manifolds, can legitimately be asserted to exist.
On Inter-Theoretic Relations and Scientific Realism
This thesis addresses three contemporary debates in the philosophy of science: namely, scientific realism, emergence, and theoretical equivalence. The thesis brings logico-semantic tools of the analytic tradition--about syntactic and semantic construals of theories, and about extensions and intensions--to bear on these debates. The thesis has two parts: Part I (Chapters 1-3) lays out the overall framework about scientific theories, scientific realism, and emergence. Part II (Chapters 4-6) develops more detailed themes. Part I first gives a conception of a scientific theory (Chapter 1), using logico-semantic tools that will be used in the rest of the thesis. Chapter 2 then brings these tools to bear on the debate about scientific realism, by construing the continuity of theories as a matter of extensions. The resulting position is a modest scientific realism, according to which one is justified in believing what confirmed theories say about extensions but not, in general, about intensions. I dub it 'extensional scientific realism'. Chapter 3 proposes an account of the distinction between ontological and epistemic emergence, based on an explication of the notion of 'novel reference'. The ontological emergence of one theory from another is defined as the failure of an appropriate linkage map between the two theories to "mesh" with the two theories' interpretations. In Part II, Chapter 4 first develops a notion of theoretical equivalence, and introduces duality in physics, as an appropriate isomorphism between theories. The Chapter discusses the relation between duality and theoretical equivalence in philosophy of science. Chapter 5 discusses the heuristic roles of dualities in theory construction. It develops a distinction between the theoretical and heuristic functions of scientific theories, and illustrates the heuristic function of duality in theory construction. Chapter 6 discusses how theories without a spacetime can lead to scientific understanding. To this end, the Chapter describes three theoretical tools that are often used in theory construction and which lead to understanding, both in cases with and cases without straightforward spacetime visualisation.