Full Idea
Beyond an innate and thus universally share protologic, each reasoner's mental logic is only more or less similar to the mental logic of any other reasoner.
Gist of Idea
Logic is personal and variable, but it has a universal core
Source
Robert Hanna (Rationality and Logic [2006], 5.7)
Book Reference
Hanna,Robert: 'Rationality and Logic' [MIT 2006], p.151
A Reaction
This is the main thesis of Hanna's book. I like the combination of this idea with Stephen Read's remark that each student should work out a personal logic which has their own private endorsement.