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The Forum is open to everyone, including students, visitors, and faculty members from all departments and institutes!

The 60 minute lecture is followed by a 10 minute break and a 30-60 minute discussion. The language of presentation is English or Hungarian.

The scope of the Forum includes all aspects of theoretical philosophy, including:

  • logic and philosophy of formal sciences
  • philosophy of science
  • modern metaphysics
  • epistemology
  • philosophy of language
  • problems in history of philosophy and history of science, relevant to the above topics
  • particular issues in natural and social sciences, important for the discourses in the main scope of the Forum.


19 November (Wednesday) 5:00 PM  Room 226
László E. Szabó
Department of Logic, Institute of Philosophy
Eötvös University, Budapest
Operationalist Approach to Quantum Theory: Two Representation Theorems
First we formulate a general framework in operationalist terms describing a typical experimental scenario in physics: one can perform different measurement operations on a physical system, each of which may have different possible outcomes. Empirical data are the observed relative frequencies of how many times different measurement operations are performed and how many times different outcome events occur, including the joint performances of two or more measurements and the conjunctions of their outcomes.
  Then we show that these empirical data always admit a classical probabilistic description in a suitable Kolmogorovian probability space, no matter whether the phenomena in question belong to classical or quantum physics. In other words, we give a proof of the Kolmogorovian Censorship Hypothesis within our general operationalist framework.
   The frequencies with which the measurement operations are performed constitute the “soft” part of the empirical data, as they may depend on circumstances outside of the physical system under consideration; for example, on the free choice of a human. Therefore we treat them as free  parameters. Under some plausible---and empirically easily verifiable---conditions, we isolate a notion in the Kolmogorovian probabilistic model, which is independent from these free parameters and describes the state of the system, in the sense that it characterizes the system's future probabilistic behavior against all possible measurement operations.
   Thus, the first representation theorem says that whatever the physical system in question is---traditionally categorized as classical or quantum---everything that can be described in empirical/operational terms can be described within the classical Kolmogorovian probability theory.
   At the same time, in a second representation theorem, we show that everything that can be described in empirical/operational terms can also be represented in the Hilbert space quantum mechanical formalism. There always exists a suitable Hilbert space such that the outcomes of each measurement can be represented by orthogonal projectors, the states of the system can be represented by suitable density operators, and the probabilities of the measurement outcomes can be reproduced by the usual trace formula of quantum mechanics. Moreover, if the measurement outcomes are “labeled” by real numbers, that is, the measurements correspond real-valued physical quantities, then each quantity can be associated with a suitable self-adjoint operator, and the expectation value can be reproduced by the usual trace formula applied to the self-adjoint operator.
   The second representation theorem can be interpreted that the basic premises of quantum theory are in fact analytic statements. They do not tell us anything new about a physical system, beyond the fact that the system can be described in empirical/operational terms.

26 November (Wednesday) 5:00 PM  Room 226
László Nemes
Is philosophy an American discipline?
Our psychologist colleagues currently began to seriously worry about a kind of cultural bias pervading the science of psychology. Psychology likes to identify itself as a science of human mind as such, but recent surveys demonstrate that, at least in leading American professional (APA) journals, the representation of our species is rather confined to people of the well-developed (WEIRD: Western, educated, industrialized, rich, democratic) countries and especially to a particular segment of the American population. This strong cultural bias might badly distort our overall picture of the mental functioning of the humankind and so undermine the original objective of scientific psychology. In my presentation, I want to suggest some analogous problems with philosophy as we mainly know it today. I will provide my own research data about leading international philosophy journals. As these data reveal, the vast majority (75%) of the authors in these journals are American, which can be a source of a cultural bias and the narrowness of the whole discipline. My research suggests that philosophy is even more American today than psychology, which was declared the most American of all the scientific fields. Especially if we accept the basic role of culturally molded intuitions in philosophy (experimental philosophers just try to convince us about it), we must be aware of this cultural bias and make steps to balance it in order to make world philosophy a more diverse and substantial enterprise.