Ah, finally an example where "the" does convey some extra information. However, > Bob: I saw the good one. Weird. Before I read your explanation I interpreted

Ah, finally an example where "the" does convey some extra information. However, > Bob: I saw the good one. Weird. Before I read your explanation I interpreted this as Alice and Bob having a prior mutual understanding about which of the movies was good and Alice immediately knows the particular movie he saw. Also, she knows that he decided upfront to watch (only) that movie. EDIT: last point, if they don't have a prior understanding about which movie is "good", Bob would have to have watched _all_ of them to be able to say "THE good one". (Because, if he only watched a subset, an unwatched movie could be better than those he watched and would make him change his mind about which one is "good"). > she has learned that Bob thinks that there is only one good movie in "those movies". According to your explanation, she still doesn't know _which_ movie he saw. She knows that only one was good and that it was the movie he saw. But then you could just say "I watched good one". > "I saw a good one" .. here, he picked a movie at random and it happened to be good. Yay, "a" does make a difference! :)