Discussion Groups / English Usage / November 2006

It appears that it was a little more complicated than that.  Morton
Cohen writes in his biography of Carroll:

   Charles did try to isolate C.L. Dodgson from Lewis Carroll.  He
   returned unopened letters that arrived at Christ Church addressed
   to Lewis Carroll; he sought, unsuccessfully, to have Bodley's
   Librarian delete from the catalogue cross-references to his two
   names; he wrote third-person letters objecting to correspondents
   making the connection.  He appealed plaintively to the editor of a
   forthcoming _Dictionary of Anonymous and Pseudonymous Literature_
   to "erase the paragraph" in which he was mentioned, adding that if
   she had ever reaped any pleasure from reading his works, "do not,
   I entreat you, repay it by the cruelty of breaking through a
   disguise which it is my most earnest wish to maintain," and here
   he succeeded.

   But none of these efforts arose out of a deep-seated duality; they
   aimed only at retaining a semblance of privacy.

The implication I take from that is that letters addressed to "Lewis
Carroll" that went to his publisher were answered; it was only those
that linked Carroll and Dodgson that he returned.  As to why, Cohen
says later

   But Charles's efforts to keep his two identities separate were
   motivated by more than his wish for privacy.  He realized that if
   the world knew that Charles Dodgson and Lewis Carroll were one,
   professional pundits might shrug off his mathematical works;
   indeed some reviews of his serious books fell into that
   superficial mode when the writers linked the two names.

So it sounds as though he was both; he just didn't want people to
realize that they were the same person.