I don’t think that explanation works. One of the standard examples of the Gettier problem is, as eli described, a case where you believe A, A is false, B is true, and the question is “do you have knowledge of (A OR B)”. The “caused by the truth of the proposition” definition is an attempt to get around this.
So your answer fails because it doesn’t actually matter that the word “insane” can mean two different things—A is “is insane like Nero”, B is “is insane in the sense of having a bad model”, and “A OR B” is just “is insane in either sense”. You can still ask if he knows he’s insane in either sense (that is, whether he knows “(A OR B)”, and in that case his belief in (A OR B) is caused by the truth of the proposition.
I don’t think that explanation works. One of the standard examples of the Gettier problem is, as eli described, a case where you believe A, A is false, B is true, and the question is “do you have knowledge of (A OR B)”. The “caused by the truth of the proposition” definition is an attempt to get around this.
So your answer fails because it doesn’t actually matter that the word “insane” can mean two different things—A is “is insane like Nero”, B is “is insane in the sense of having a bad model”, and “A OR B” is just “is insane in either sense”. You can still ask if he knows he’s insane in either sense (that is, whether he knows “(A OR B)”, and in that case his belief in (A OR B) is caused by the truth of the proposition.