International congress of byzantine studies belgrade, 22 27 august 2016

Dmitri Chernoglazov
St. Petersburg State University, St. Petersburg, Russian Federation; 
[e-mail] 
Whether Theodoros Prodromos Invented the Russel Paradox?
“Xenedemos, or Voices” (Ξενέδημος ἢ Φωναί), a little-known philosophical work by Theodoros 
Prodromos, is dedicated to the analysis of the five “voices” or predicabilia (φωναί) definitions made 
by Porphyry in “Isagoge”. The way to discuss the definitions of Porphyry that Theodoros Prodromos 
uses is to make a presentation of logical puzzles just to invite the reader to produce the outlines of 
their possible solutions. The logical content of «Xenedemos» might be substructured into three 
levels: didactical, analytical and philosophical one.
Analytical level.
“Xenedemos” offers a critical analysis of the five Porphyrian predicabilia definitions. According 
to this task the dialogue is devided into five main parts, each of them is dedicated to genus (γένος), 
species (εἶδος), differentia (διαφορά), property (ἰδίον) and accident (συμβεβηκός). By the end of each 
part the participants of the dialogue come to aporia or a mistake using the apparatus of Porphyry. 
It is very interesting to determine the logical status of Theodoros Prodromos critical receptions of 
Porphyrian definitions: whether they are paralogisms, sophisms, aporias or paradoxes?
Didactical level.
It is not hard to demonstrate that “Xenedemos” is an educational dialogue written as a series 
of logical puzzles which could be objects for the reader’s possible solutions. 
Philosophical level.
The philosophical level represents the problem of self-reference as a basic feature of predicabilia 
notions in the situations when they are applied to define themselves. It should be noted that Theodoros 

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Prodromos might have formulated the Russel paradox using the five “voices” of Porphyry. So this 
dialogue can be regarded as the text on the foundations of logical theory of definition.
It should be mentioned that the dialogue is an original work, which reflects new trends in the 
12
th
c. Byzantine literature. Such Byzantine intellectuals as Michael Psellos, John Italos, Michael 
Italikos and Theodoros Prodromos himself could be prototypes of the protagonists of the dialogue. 
It should be noted that the ideas of Theodoros Prodromos are interesting in historical, logical, 
philosophical and literature development perspectives. 
The research is supported by the Russian Foundation for Humanities, № 15-03-00138 «Ancient 
logic and Byzantine intellectual tradition: aspects of reception».