TITLE: About Jean-Yves Girard
QUESTION [14 upvotes]: I am student and I'm studying linear logic. I saw a quote in a book:
"I'm not a linear logician" - Jean-Yves Girard. Tokyo, April 1996.
I searched on Google but I did not find the context of why he said it. What he meant by that phrase?

REPLY [19 votes]: As suggested by @rschwieb, I sent an email to Girard. Here is his answer:

Hi,
The general idea is that logic should not have an adjective: look
  at modal, non-monotonic, paraconsistent logics in which the 
  adjective is a sort of negation, like in « military justice ».
Linear logic is just a way to do plain logic, i.e. to study pure reasoning.
  My position was that linearity is a question of fine structure: even if you
  are concerned with intuitionism, the use of linearimplication can be very 
  helpful.
More recently I discovered that predicate calculus is based on a mistake,
  namely the idea of « a property of individuals » P(t): we cannot speak of
  « blue » but only say « the sky is blue ». This realistic contraption makes
  equality a nonsense. It is indeed possible to expel the « individuals » and
  replace them, when needed, with linear propositions T, U, V, in which case
  equality becomes linear equivalence. For this we absolutely need linearity
  since we can prove (classically or intuitionistically) that there are no
  more than two « individuals ». 
To sum up, I am not a linear logician because the natural treatment of logic
  compels us into using linearity, this independently of any commitment.
Best regards,
J-YG