You've described "Top Down" and "Bottom Up" means of knowledge production. Often cast as rationalism and empiricism respectively. One favours knowledge that is known already and seeks to generalise that to explain the world, and the other favours knowledge that is produced trying to deal with specific problems on a case-by-case basis.

Each approach has it's conceits, strengths and weaknesses but truth emerges where these are reconciled and a synthesis is arrived at.