Monthly Philosophy Seminar RCGPh AA acad. year 2023-2024


The Research Centre for Greek Philosophy at the Academy of Athens

Invites you in the course of the Monthly Philosophy Seminar

to the lecture which will take place on

Wednesday 15 November 2023, 16:00-18:00 (ATH, GR timezone) at the Elli Lambridis Philosophical Library (9 Hypsilantou str., Athens).

Speaker: Michel Crubellier, Emeritus Professor of Philosophy at the University of Lille,

Topic: How is it possible to claim that every συλλογισμός is a syllogism?


Those interested may attend either in person or via Zoom.




I intend to examine and – to some extent – vindicate two important claims made by Aristotle at the outcome of the two main theoretical elaborations of Prior Analytics Book 1, namely the ‘Syllogistic’ (1.1-7) and the Pons Asinorum (1.27-30):

‘Every deduction (συλλογισμός) must necessarily come about through the three figures described above’ (1.23, 41b1-3)

‘It is evident (…), not only that it is possible for all deductions (συλλογισμοί) to come about through this route [= the machine of the Pons Asinorum], but also that this is impossible through any other’. (1.29, 45b36-38)

These claims are often criticized as being exceedingly confident; the more so if – as I think we should – one does not take συλλογισμός in the sense of the specific forms of argument (figures and ‘moods’) discussed in chapters 1.4-7, but in its broader dialectical sense, meaning any compelling argument based on explicitly assumed premises. For it seems that there are many kinds of arguments which cannot fit in with the models introduced in the Syllogistic or in the Pons Asinorum section: suffice it to mention proofs by reduction to impossibility and most mathematical, especially geometrical, proofs.

However, Aristotle himself explicitly mentions some such cases in the very chapters in which he argues for those two claims: he declares that he has, or at least aims at and discerns, a solution for the case of proofs by reduction, and he uses mathematical examples in order to illustrate his views. The notion that he could have considered that such cases were but unimoprtant exceptions seems very hard to swallow.


So, the aim of this presentation, centered mainly on the first claim and on chapter 1.23, is to look more closely at the passages in which he mentions these cases in order to grasp better how he could have apprehended them (using part of that time for the discussion of mathematical examples).

I will reach the conclusion that both claims are much more defensible than it is commonly said, if we can reconsider and flesh out our understanding of some of the basic terms in which he addresses the problem and of its inscription in a dialectical perspective. Notably, I suggest understanding some concepts (for instance ὑπάρχει τῷ Α, or ὅρος) in a sense broader than that in which they are usually taken, but in my view they must not become vague or confused.

However, the effectivity of that solution remains uncertain in the case of ‘deductions fom assumption’.

As a side-lesson of that first conclusion, I will end with a reflection on the heuristic value of the Pons Asinorum machine and its limits, and on the epistemological meaning of the second claim. 



October 25, Doukas Kapantaïs

Prior Analytics 1.23; an elimination theorem to avail the scientist and the dialectician alike


November 15, Michel Crubellier

How is it possible to claim that every συλλογισμός is a syllogism?


December 6, Marko Malink

Aristotle on reductio ad impossibile: from dialectic to syllogistic logic


January 17, Christof Rapp

Reasonableness of Argument and strategic maneuvering in Topics VIII


February 28, Mathieu Marion

Semantics of Interaction: A New Perspective on the relation between Topics and Prior Analytics


March 20, Paolo Fait

How can the investigation of demonstration and demonstrative science (Prior Analytics 1.1 24a10–11) accommodate dialectical syllogisms?


April 3, Gisela Striker

The place of dialectic in Aristotle's Prior Analytics


May 15, Laura Castelli

Universal premises in the Topics


May 29, Colin G. King

Language formalization in the Topics and the Prior Analytics


June 12, Zoe McConaughey

Syllogistic and dialogues


Wednesday, November 15, 2023
Announcement Type: