whai i feel that premise is the basis or the propositon on which any deductive argument is based.. and it is not always evidential that why we have lot of time faulty premises when we cud not prove the logic..it cud be a prposition of a syllogism from which conclusion is drawn.
for ex statement a and b r premises
a: all birds fly
b: crow is a birds
and the conclusions c: all crows fly
on the other hand the assumption can be evidential based on ones sensory or theoretical experiences..
in logic it is mostly a minor premise.