As a student I learned strange grammatical constructions without giving much thought to them–constructions like the subjunctive in indirect questions, or after the conjunction “cum”. But now I like to try to make sense out of such things. In the text book Bradley’s Arnold, we read in regards the use of the subjunctive in indirect questions “The subjunctive in such clauses is simply the mood of subordination; it has here no distinctive meaning of it’s own.” Well, that’s what the text book says, but I notice that in English we sometimes use the subjunctive in indirect questions. Instead of “I wonder what the answer is.”, we can say “I wonder what the answer would be.” Or we can say “The officer asked what my name would be.”, or in colloquial English “I don’t know whether the Smiths would be going to Europe this summer.”
Based on the English usage, the mandatory use by Latin of the subjunctive in indirect questions does not seem so unreasonable. I suppose that the speakers of Latin felt that an indirect question was asking for an affirmation, something less that a fact. Anyway, that’s how I make sense out of that particular and odd use of the subjunctive. Of course, my line of reasoning that makes sense to me, may possibly not make sense to other people.