Full Idea
We would have no fully-fledge thoughts if we were not in communication with others.
Gist of Idea
Thought is only fully developed if we communicate with others
Source
Donald Davidson (Davidson on himself [1994], p.233)
Book Reference
'A Companion to the Philosophy of Mind', ed/tr. Guttenplan,Samuel [Blackwell 1995], p.233
A Reaction
This seems a plausible empirical observation, though I would doubt any a priori proof of it. If animals could speak, they would become intellectuals?