The producers have said over and over that they aren't dead.

If Jack is dead and the others are somehow alive, why would the island use Jack's Father to send Vincent to wake up Jack when it could just wake up Jack on it's own?

This whole the Island won't let you stuff bothers me. The producers have said everything could be explained using some sort of science, and I don't see how the island could be explained (unless it's some kind of alien !!)