[FOM] non-Euclidean geometry and FOM programs

Antonino Drago drago at unina.it
Wed Nov 7 16:12:23 EST 2007

> Sunday, October 28, 2007 11:59 PM I wrote:
>> In fact, the radical change is substantiated in both Lobachevsky's and
>> Bolyai's
>> texts the essential use of a great number of sentences which are not
>> equivalent to the
>> corresponding positive sentences; hence, the failure of the double
>> negation law; which at present we know introduces grosso modo a
>> non-classical logic, intuitionist logic as first.
> Monday, October 29, 2007 5:00 PM Andre Rodin wrote:
> Could you probably be more specific about this? Sounds very interesting 
> but
> I cannot see the link. A logician directly influenced by Lobachevsky was
> Vasiliev whose "Imaginary logic" is usually viewed today as anticipating
> paraconsistent logics - but this seems to be quite a different story.

My answer:  In fact never Lobachevsky wrote "There exist two parallels", 
rather (I mark
 by two asterisks each negative word)
 "The... assumption can likewise admitted *without* leading top any
 *contradiction* in the results.." (the end of proposition no. 22 in
 Geometrical Studies..., an appendix to R. Bonola: Non-Euclidean Geometry,
 Dover, 1955)
 "1° Dans la théorie *rien* *ne s'oppose* à admettre que la somme des angles
 d'un triangle rectiligne soit moindre que deux angles droits" 2° Dans
 l'hypotèse de la somme des angles d'un triangle moindre que deux angles
 droits, les équations (13) peuvent etre substituées aux équations 
 (15) *sans* mener jamais à quelques résultats *absurdes*....."(Géométrie
 Imaginaire, J. Crelle, 17 1837, p. 302)

> Sunday, October 28, 2007 11:59 PM I wrote:
>> In Lobachevsky's mind this radical change in the way of
>> arguing may be put in connection to the first Russian translation in his
>> little and far town, Kazan, of Lazare Carnot's celebrated book
>> on calculus, whose final "Note" explained the two different method of
>> arguing
>> inside a scientific theory, i.e. the analytic one and the
>> syntethtic one.
> > Monday, October 29, 2007 5:00 PM Andre Rodin wrote:
>This is particularly interesting given the long passage on the distinction
> btw analytic and synthetic methods Lobachevsky provides in the Intro to 
> his
> New Foundations of Geometry of 1835. Do you have the reference to the
> Russian translation of Carno's book?
My answer: C..C. Gillispie Lazare Carnot Savant, Princeton U.P., Princeton, 
1971 gives
 the complete bibliography of L. Carnot, included the foreign versions of 
 books; the Russian version was edited when Lobachevsky was was both Dean of
 the Philosophical Faculty and the librarian of the University of the very
 little town of Kazan .  Moreover, Lobachevsky wrote two "Outline" of his
 course on geometry; the second uncensored version quotes L. Carnot. See 
 Lobachevskii, Collected Scientific and Pedagogical Papers ( eds. A.
 Alexandrov, B.L. Laptev, in Russian), Nauka, Moscow, 1976 which adds some

Best regards

Antonino Drago:

More information about the FOM mailing list