Full Idea
Someone cannot have a belief unless he understands the possibility of being mistaken.
Gist of Idea
Having a belief involves the possibility of being mistaken
Source
Donald Davidson (Thought and Talk [1975], p.170)
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.170
A Reaction
If you pretend to throw a ball for a dog, but don't release it, the dog experiences being mistaken very dramatically.