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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.



11 October (Wednesday) 5:00 PM  Room 226
Péter Juhász* and Gergely Székely**
 *Institute of Philosophy, Eötvös University, Budapest
**Rényi Institute of Mathematics, Budapest
On using iteration and fixpoint theorems for resolving causal paradoxes connected to time travel 
This talk is a revisited version of a previous LaPoM presentation, focusing more on the technical parts of the framework. We are going to discuss the topic in a self-contained way, begin with the introduction of temporal paradoxes: causal loops and consistency paradoxes, outdraw possible solutions and present our framework developed to be a general method of giving a self-consistent model for every possible initial data.
The main subject of the talk is going to be the framework itself. The goal is to delve into the details of the formal components, that is, to display our ideas by explicit and precise definitions. Then discuss the results and setbacks of our approach, such as a local counter example showing that the self-consistent solutions cannot always be found in nearby worlds by simple iteration.

18 October (Wednesday) 5:00 PM  Room 226
Gábor Forrai
Institute of Business Economics, Eötvös University, Budapest
  Hibáztathatóak vagyunk-e hiteinkért? Doxasztikus deontológia akaratlagos ellenőrzés nélkül
(Can we be blamed for our beliefs? Doxastic deontology without volumtary control)
 A doxasztikus deontológia szerint az ismeretelmélet területén éppúgy beszélhetünk kötelességről és felelősségről, mint az etika területén, azaz bizonyos körülmények fennállása esetén kötelező vagy éppen tilos ebben vagy abban hinnünk, és számon kérhető rajtunk, ha nem így teszünk. Az előadásban első felében William Alstonnak a doxasztikus deontológia ellen szóló érvével vitatkozva el fogom magyarázni, hogy a deontikus kifejezéseket a doxasztikus állapotokra vonatkoztatva hogyan kell értelmezni. A második felében azt vizsgálom, hogy ez a felfogás összeegyeztethető-e a naturalista programmal, s Hilary Kornblith naturalizált felfogását elemezve amellett fogok érvelni, hogy a deontológiának legfeljebb egy része illeszthető be a naturalizált ismeretelméletbe.

25 October (Wednesday) 5:00 PM  Room 226
Koen Lefever
Centre for Logic and Philosophy of Science, Vrije Universiteit Brussel
Comparing Classical And Relativistic Kinematics In First-Order Logic*
Joint research with Gergely Székely (Rényi Institute of Mathematics, Budapest)
The aim of the research presented in this talk is to establish a new logic-based understanding of the connection between classical kinematics and relativistic kinematics. We work in the framework and the tradition of the Andréka--Németi school of axiomatic relativity as developed at the Algebraic Logic department of the Alfréd Rényi Institute of Mathematics.

We show that the axioms of special relativity can be interpreted in the language of classical kinematics. This means that there is a logical translation function from the language of special relativity to the language of classical kinematics which translates the axioms of special relativity into consequences of classical kinematics.

We will also show that if we distinguish a class of observers (representing observers stationary with respect to the “ether”) in special relativity and exclude the non-slower-than light observers from classical kinematics by an extra axiom, then the two theories become definitionally equivalent (i.e., they become equivalent theories in the sense that the theory of lattices as algebraic structures is the same as the theory of lattices as partially ordered sets).

Furthermore, we show that classical kinematics is definitionally equivalent to classical kinematics with only slower-than-light inertial observers, and hence by transitivity of definitional equivalence that special relativity theory extended with “ether” is definitionally equivalent to classical kinematics.

So within an axiomatic framework of mathematical logic, we explicitly show that the transition from classical kinematics to relativistic kinematics is the knowledge acquisition that there is no “ether”, accompanied by a redefinition of the concepts of time and space.

The above allows us to introduce a metric "conceptual distance" between theories: theories which are equivalent have a conceptual distance of zero, while the distance between non-equivalent theories is the number of concepts which need to be added or subtracted to make them equivalent. Since the only concept which need to be added to relativistic kinematics to make it equivalent to classical kinematics is the "ether", the conceptual distance between both theories is "one".