To have
faith in is to
trust in.
A specific type of faith called blind faith is what you get when your trust is baseless. However,
there really is never a case of blind faith since faith is always
based on something. For example, the base of some peoples' religious faith
is a subjective experience.
As humans it is very difficult if not impossible for us to
absolutely prove most things. When it comes time for us to
make a decision we are not taking into account the possibility
that the laws of physics will radically change. This is because we
have a very high faith in the constancy of these laws.