When a person begins with the larger question itself, he inevitably winds up confronting his own ignorance and trying to find ways to fill in the gaps in his knowledge. The person who begins with a position on the issue never sees his own ignorance, and in fact, deliberately avoids seeing his own ignorance. The person who begins with a position on the issue and argues for that position naturally tries to hide his ignorance of the smaller issues, since the things that he doesn't know are a weakness in his argument. The person who begins with the question itself, on the other hand, inevitably winds up reveling in his own ignorance, celebrating his ignorance, and sharing it freely with the world at large.
The person who begins with a position on the issue, by this process, becomes a borrower from the Bank of Knowledge. He borrows from the things that others know, and uses them to construct an argument.
The person who begins with the question itself, on the other hand, eventually becomes a contributor to the Bank of Knowledge. Forced to confront his own ignorance, he is forced to find ways to figure out the information that he is missing - ways to count things that haven't been counted, or ways to estimate the parameters of things that are unknown. Through this process, he winds up contributing things that were not known before.