Topics in the Philosophy of Science

"Philosophy of science" is usally contrasted with the philosophy of special sciences, and I certainly recognize an important distinction between it and the philosophy of physics; but still I think that physics has a very special place in scientific epistemology. In part this derives from its special status vis a vis mathematics, and the place of mathematics in science, and in part it derives from the special status of physics in the history of science. I take it that we are bound to respond to Kuhn's thesis, and to Laudan's critique of the thesis of convergence in science.

Dynamics plays a special role in physics. Most of my work in general philosophy of science has consisted in the attempt to say what is special about it, and its historical development. For an accumulativist view of dynamical theory, see my:

  • "To What Physics Corresponds", in Correspondence, Invariance, and Heuristics; Essays in Honour of Heinz Post, S. French and H. Kaminga, (eds.), Kluwer, p.295-326 (1993).
  • For an analysis of Hertz's dynamics, and a sustained criticsm of his philosophy (and the conventionalist movement that it gave rise to), see my:

  • "Hertz's Principles", in Heinrich Hertz: Classical Physicist, Modern Philosopher, D. Baird et al, (eds.), Kluwer (1998).
  • The first of these papers points to a more structuralist view of dynamical theories, roughly along Worrall's lines, although to my shame I was ignorant of Worrall's work when I wrote it. Here I emphasized the difficulty posed by the problem of measurement to claims of convergence in physical theory, but by the same token, insofar as physicists and philosophers of physics have expended quite a lot of energy to solve it - with at least partial success - talk of incomnensurability between classical and quantum mechanics is clearly inappropriate.

    In my recent review of Cao's book on the history of field theories:

  • "Critical Notice: Cao's 'Conceptual Development of 20th Century Field Theories'", Synthese, 136, 79-105 (2003). Click here to download as a pdf file.
  • I tried to take up Cao's attempt to sidestep the problem of measurement, whilst yet giving an accumulativist account of dynamical theories, by providing a very weak reading of structuralism, sketching important cases where the same dynamical structures arrise in very different kinds of physical substrata. But this approach leads to a broad class of metaphysical questions which connect both to the interpretation of symmetries and certain approaches to the problem of measurement (see my space and Everett webpages). One cannot really get away from the problem of measurement, in my view.

    The treatment of symmetry in physics in turn leads to other questions which are broadly linguistic: how do we make reference to objects in the face of symmetries? There are well-known examples (Black's two iron spheres; Strawson's symmetric checker-board); the problem goes back to Kant and ultimately to Leibniz. Strangely, the resources of post-Fregean logic have rarely been properly plumbed in formulating a criterion or definition of identity. There is only one reasonable definition from a logical point of view, and that is due to Hilbert and Bernays, following Godel's axiomatization of identity. It was championed by Quine, but was never exploited in the context of philosophy of science. Quine was interested in it because it lent support to his view of logical truth as truth by virtue of grammatical form; only the identity sign, used as primitive, has a "meaning" in logic that extends beyond syntax.

    If we follow Quine, but with reference to the ongoing interpretation of physical theories - in our talk about the world as informed by scientific theories - we have a servicable definition of indentity that is robust in the face of all the usual conundrums (save one). With this one has a check on ontology - objects, identity, and predicates may come all together, in interpretation, but let them come as a package: I take a principle of identity of indiscernibles as a methodological principle in interpretation, on a par with Occam's razor. This perspective, and its application to most of the exact symmetries of physics, is laid out in

  • "Physics and Leibniz's Principles", in Symmetries in Physics: Philosophical Reflections, K. Brading and E. Castellani, eds., Cambridge University Press (2003). Click here to download as a pdf file.
  • I say the approach is successful in every case save one: the exception is elementary bosons. They, alone of the common objects of physics, are not objects by my lights. It is modes of the quantum field that we should talk of instead, and their attributes, among them an integral measure of intensity. That is what photon number is in my books. If this is accepted, and all the objects of physics fall into place in a framework that from a logical point of view is conservative, what price structuralism? I return to this question in

  • "Structural Realism, Again"
  • , Synthese, 136, 127-33 (2003). Click here to download as an html file.

    I take it up again in

  • Are Quantum Particles Objects?, Analysis,66, 52-63 (2006), and in a href="explanation.pdf">On the Explanation for Quantum Statistics, Studies in the History and Philosophy of Modern Physics, 37, 192-211 (2006). See also my treatment of a space-time discrete symmetry, Mirroring as an A Priori Symmetry, Philosophy of Science, forthcoming. They are all downloadable as pdf documents.

    A further topic in philosophy of science that I will mention here has its roots in quantum mechanics. It is the question of scientific rationality, specifically over the interpretation of quantum mechanics in the first half of the 20th century. Here a challenge was issued by Jim Cushing in his book "Quantum Mechanics: Historical Contingency and the Copenhagen Hegemony" (Chicago 1994). The title says it all: the physics community walked away from pilot-wave theory in 1927, embracing Bohr's theory of complementarity instead; complementarity has been held in low esteem by philosophers of physics in recent times; were the choices of the community rational? Cushing says not, a point of view enthusiastically taken up by the sociologists. But this is a debate brought to an untimely halt by Jim's sudden death in 2002. It is, therefore, to his memory and not to the man that I address the arguments of my paper

  • "Complementarity and Scientific Rationality", Foundations of Physics>,35, 347-72. Click here to download as a pdf file.
  • Jim was a good friend and colleague and he will be sorely missed. Never more so, for me, then when it comes to discussion of this matter. This paperappears in the volume of Foundations of Physics dedicated to his memory.

    Copyright Simon Saunders 2001. Last updated: 8 December 2007.