Quite rightly, philosophers of physics examine the theories of physics, theories like Quantum Mechanics, Quantum Field Theory, the Special and General Theories of Relativity, and Statistical Mechanics. Far fewer, however, examine how these theories are put to use; that is to say, little attention is paid to the practices of theoretical physicists. In the early 1950s David Bohm and David Pines published a sequence of four papers, collectively entitled, ‘A Collective Description of Electron Interaction.’ This essay uses that quartet as a case study in theoretical practice. In Part One of the essay, each of the Bohm-Pines papers is summarized, and within each summary an overview is given, framing a more detailed account. In Part Two theoretical practice is broken into six elements: (a) the use of models, (b) the use of theory, (c) modes of description and narrative, (d) the use of approximations, (e) experiment and theory, (f) the varied steps employed in a deduction. The last element is the largest, drawing as it does from the earlier ones. Part Three enlarges on the concept of ‘theoretical practice,’ and briefly outlines the subsequent theoretical advances which rendered the practices of Bohm and Pines obsolete, if still respected.
R.I.G. Hughes teaches in the Philosophy Department of the University of South Carolina. Published works include The Structure and Interpretation of Quantum Mechanics, Harvard University Press, 1989; Philosophical Perspectives on Newtonian Science (co-edited with Phillip Bricker), M.I.T. Press, 1990; Heinrich Hertz: Classical Physicist, Modern Philosopher (co-edited with Davis Baird and Alfred Nordmann), Kluwer, 1998; A Philosophical Companion to First-Order Logic (edited), Hackett, 1993. Present project is a book (roughly 90% written) to be entitled The Practice of Theory, Essays in the Philosophy of Physics.