The possuk says ’Riai….habracha vhakalala’, see I am giving you blessings and curses. The commentators explain the difference between Klal Yisrael and the other nations. For all other nations, the world is built on teva, nature.  Basically, the world has food ,diseases, wars, that generally follow a normal set of laws, unless there is a great reason to change.  Klal Yisrael is different. They are given either blessings or curses, there is no teva. If they are good they get blessings and if they are bad they get cursed, with no in between. This is the meaning of ‘blessings and curses’ in the posuk, you get either/or not like everyone else.