Science based knowledge is based on factual observations, from this scientist create a framework which explains the particular phenomena. As more detailed or complex observations are made, the explanation - which may be a theory (in the scientifice sense) but doesn't have to be - is adjusted to account for the new data. The old facts however must also be taken into account and while explanations are subject to tweaking and the occasional overhaul facts tend to be more permanent.
The assertion that we can only know anything only if we know evertying is ridiculous and you refute it in your everyday life.
BTW Why does blackngold keep calling everyone Corinthian?