I thought that they all might be in an elaborate virtual reality world in order to find themselves. The "others" are doctors and nurses who kill off the ones who have been cured .
Jack is an alcoholic...hurley has bulimia, locke has psycosematic paraplegia, kate is a paranoid schitzophrenic...etc etc.
And along the way there are some prisoners in the same hospital as part of a rehabilitaion programme, like Sawyer, mr echo and Andalucia (or Kate).
Maybe I've got it all wrong but maybe Hurley has the key to it all the answers.
Michael's boy is not supposed to be there for some reason.