Full Idea
If learning that fish typically live in streams is part of learning "fish", typical utterances of "pet fish" (living in bowls) are counterexamples. This argument iterates (e.g "big pet fish"). So learning where they live can't be part of learning "fish".
Gist of Idea
If to understand "fish" you must know facts about them, where does that end?
Source
Jerry A. Fodor (In a Critical Condition [2000], Ch. 5)
Book Reference
Fodor,Jerry A.: 'In Critical Condition' [MIT 2000], p.57
A Reaction
Using 'typical' twice is rather misleading here. Town folk can learn 'fish' as typically living in bowls. There is no one way to learn a word meaning.