The demographic argument

Here, ultimately, is all you really need to know about disengagement and the general policy of exiting from the occupied territories:

[F]or the first time, the proportion of Jews living in territories under the country's control has dropped below 50 percent, standing slightly more than 49 percent .The results are based on figures supplied by Israel and the Palestinian Authority's official statistics bureaus. According to the figures, following the upcoming disengagement, the proportion of Jews in territories under Israeli control will jump to 56.8 percent. As a result of this development, demographic expert Prof. Sergio Della Pergola of the Hebrew University said the country is ensured of a Jewish majority within its territories for the next 20 years.

As Ariel Sharon realized several years ago, from a purely selfish Jewish point of view, case closed.