Full Idea
Without a 'teacher', nothing would give content to the idea that there is a difference between getting things right and getting them wrong.
Gist of Idea
Without a teacher, the concept of 'getting things right or wrong' is meaningless
Source
Donald Davidson (Davidson on himself [1994], p.234)
Book Reference
'A Companion to the Philosophy of Mind', ed/tr. Guttenplan,Samuel [Blackwell 1995], p.234
A Reaction
Seems right. A group of speculators with no one in the role of 'teacher' would seem to be paralysed with uncertain (except where judgements are very obvious).