Sigma Club

Where Kuhnian Incommensurability Leaves Us: a Lesson from the Crisis of the Old Quantum Theory

  • Monday, 9 May 4:00 - 6:00pm
  • Michela Massimi
  • Cambridge

Michela Massimi

In his later writings, Thomas Kuhn reinterpreted incommensurability as untranslatability between scientific lexicons. In this view, scientists using different scientific lexicons would resort to different lexical taxonomies that cannot be inter-translated. In this talk I shall investigate Kuhn's argument for untranslatability and question some of its crucial assumptions about lexical taxonomies. I shall support and illustrate my criticism of Kuhn with the historical case study concerning the emergence of the new concept of electron's spin during the revolutionary transition from the old quantum theory to the new quantum theory around 1925.

Quantum Propensities and the Problem of Measurement

  • Monday, 23 May 4:00 - 6:00pm
  • Mauricio Suárez
  • Universidad Complutense de Madrid

Mauricio Suárez
Universidad Complutense de Madrid

In the first part of the talk an overview is provided of the history of uses of the notion of propensity in order to interpret quantum mechanics, with particular emphasis on the accounts by Henry Margenau and Karl Popper. I discuss empirical and conceptual objections to these accounts, and then go on to provide a new conception of a quantum propensity that can account for their deficiencies. This notion of quantum propensity is neutral with respect to the metaphysical issue regarding whether propensities are real properties or empirical regularities. It provides, in conjunction with an account of measurements as selections, natural solutions for both the quantum measurement problem and the paradox of the distant EPR correlations.


Fine, "With Complacency or Concern: Solving the Quantum Measurement Problem", in Kelvin's Baltimore Lectures and Modern Theoretical Physics: Historical and Philosophical Perspectives, MIT Press, Cambridge, pp. 491-505.
Margenau, H. (1954), The Nature of Physical Reality, McGraw-Hill, New York.
Popper, K. (1957), "The Propensity Interpretation of the Calculus of Probability, and the Quantum Theory", in S. Körner (ed.), Observation and Interpretation in the Philosophy of Physics, pp. 65-70.
Redhead, M. (1987) Incompleteness, Non-Locality and Realism, Oxford University Press, pp. 48-49.
Suarez, M. (2004), "Quantum selections, propensities and the problem of measurement", British Journal for the Philosophy of Science, 55 (2), pp. 219 - 255.
Suarez, M. (2004), "On Quantum Propensities: Two Arguments Revisited", Erkenntnis, 61, pp. 1-16.

Quantum Information Does Exist

  • Thursday, 9 June 4:00 - 6:00pm
  • Armond Duwell
  • University of Konstanz

Armond Duwell
University of Konstanz

In recent years, some physicists and philosophers that have claimed that the relatively new field of quantum information theory will revolutionize our understanding of the nature of the quantum world. In particular, the concept of "quantum information" is to play a major role. Exactly what kind of role quantum information could play in the foundations of quantum theory is not clear. Some have been dubious, others quite optimistic. Part of the problem is that there is no precise account of what quantum information is. In this lecture I attempt to rectify this problem by offering a precise account of quantum information and offer some tentative assessments of its ability to help us understand the quantum world.