Every time I see the news of new settlements being built I clench up.  Why? Why now?  I know there is ideology and politics involved and I know I am very opposed to the concept of settlements, but I try every time to understand exactly what are the mechanics of the decisions.  I never get it.  What make them decide to allow exactly 1,500 palestinian units and build 3000 israeli units?  what is the mathematics based on?  Can someone tell me?