Full Idea
I may be the final authority on whether my shoe pinches, but I am manifestly not the final authority on whether I understand some mathematical theorem.
Gist of Idea
I'm not the final authority on my understanding of maths
Source
Keith T. Maslin (Introduction to the Philosophy of Mind [2001], 1.7)
Book Reference
Maslin,Keith: 'An Introduction to the Philosophy of Mind' [Polity 2001], p.23
A Reaction
However, it doesn't follow that his teachers are the final authority either, because he may get correct answers by an algorithm, and bluff his way when demonstrating his understanding. Who knows whether anyone really understands anything?